U.S. patent application number 14/931169 was filed with the patent office on 2016-02-25 for systems and methods for secure workgroup management and communication.
The applicant listed for this patent is Security First Corp.. Invention is credited to Stephen C. Bono, Roger S. Davenport, Matthew D. Green, Gabriel D. Landau, Mark S. O'Hare, Rick L. Orsini.
Application Number | 20160056956 14/931169 |
Document ID | / |
Family ID | 40683120 |
Filed Date | 2016-02-25 |
United States Patent
Application |
20160056956 |
Kind Code |
A1 |
O'Hare; Mark S. ; et
al. |
February 25, 2016 |
SYSTEMS AND METHODS FOR SECURE WORKGROUP MANAGEMENT AND
COMMUNICATION
Abstract
A secure data parser is provided that may be integrated into any
suitable system for securely storing and communicating data. The
secure data parser may split or share a data set into multiple
portions that are stored or communicated distinctly. Encryption of
the original data, the portions of data, or both may be employed
for additional security. The secure data parser may be used to
protect data in motion by splitting an original data set into
portions of data that may be communicated using one or more
communications paths. Secure workgroup communication is supported
through the secure distribution and management of a workgroup key
for use with the secure data parser.
Inventors: |
O'Hare; Mark S.; (Coto De
Caza, CA) ; Orsini; Rick L.; (Flower Mound, TX)
; Bono; Stephen C.; (Baltimore, MD) ; Green;
Matthew D.; (Baltimore, MD) ; Landau; Gabriel D.;
(Baltimore, MD) ; Davenport; Roger S.; (Campbell,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Security First Corp. |
Rancho Santa Margarita |
CA |
US |
|
|
Family ID: |
40683120 |
Appl. No.: |
14/931169 |
Filed: |
November 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14181257 |
Feb 14, 2014 |
9215218 |
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14931169 |
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12391025 |
Feb 23, 2009 |
8656167 |
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14181257 |
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61147961 |
Jan 28, 2009 |
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61066699 |
Feb 22, 2008 |
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Current U.S.
Class: |
713/171 |
Current CPC
Class: |
H04L 63/061 20130101;
H04L 2209/24 20130101; H04L 63/065 20130101; H04L 63/068 20130101;
H04L 63/0846 20130101; H04L 63/0428 20130101; H04L 63/067 20130101;
H04L 9/0822 20130101 |
International
Class: |
H04L 9/08 20060101
H04L009/08; H04L 29/06 20060101 H04L029/06 |
Claims
1. (canceled)
2. A method for securing workgroup communications between a first
workgroup client and a second workgroup client, the method
comprising: receiving a request to initiate a communication session
between the first workgroup client and the second workgroup client,
wherein the first workgroup client is associated with a first
encryption key, and wherein the second workgroup client is
associated with a second encryption key; encrypting a workgroup key
using the first encryption key to generate a first encrypted
message; encrypting the workgroup key using the second encryption
key to generate a second encrypted message; and transmitting the
first encrypted message and the second encrypted message to the
first workgroup client, wherein the first encrypted message and the
second encrypted message are usable to secure a workgroup
communication between the first workgroup client and the second
workgroup.
3. The method of claim 2, wherein the workgroup communication
comprises the second encrypted message.
4. The method of claim 2, wherein the first encryption key
comprises one of a public key of the first workgroup client or an
encryption key that is shared between the first workgroup client
and the workgroup key server.
5. The method of claim 2, wherein the second encryption key
comprises one of a public key of the second workgroup client or an
encryption key that is shared between the second workgroup client
and the workgroup key server.
6. The method of claim 2, wherein the first encryption key and the
second encryption key comprise symmetric encryption keys, and
wherein the first workgroup client does not have access to the
second encryption key, and wherein the second workgroup client does
not have access to the first encryption key.
7. The method of claim 2, wherein the first encrypted message and
the second encrypted message each include an identification of the
first workgroup client and the second workgroup client.
8. The method of claim 2, wherein the first encrypted message and
the second encrypted message are transmitted by the workgroup key
server in response to the request from the first workgroup client
to initiate the communication session with the second workgroup
client.
9. The method of claim 2, wherein the first encrypted message and
the second encrypted message further include at least one of a
timestamp associated with creation of the workgroup key and a
version number associated with the workgroup key.
10. The method of claim 9, wherein the timestamp and/or the version
number is usable to determine whether the workgroup key is
expired.
11. The method of claim 2, wherein the workgroup communication
comprises a plurality of share headers that are associated with a
plurality of shares.
12. A system for securing workgroup communications between a first
workgroup client and a second workgroup client, the system
comprising: a workgroup key server configured to: receive a request
to initiate a communication session between the first workgroup
client and the second workgroup client, wherein the first workgroup
client is associated with a first encryption key, and wherein the
second workgroup client is associated with a second encryption key;
encrypt a workgroup key using the first encryption key to generate
a first encrypted message; encrypt the workgroup key using the
second encryption key to generate a second encrypted message; and
transmit the first encrypted message and the second encrypted
message to the first workgroup client, wherein the first encrypted
message and the second encrypted message are usable to secure a
workgroup communication between the first workgroup client and the
second workgroup.
13. The system of claim 12, wherein the workgroup communication
comprises the second encrypted message.
14. The system of claim 12, wherein the first encryption key
comprises one of a public key of the first workgroup client or an
encryption key that is shared between the first workgroup client
and the workgroup key server.
15. The system of claim 12, wherein the second encryption key
comprises one of a public key of the second workgroup client or an
encryption key that is shared between the second workgroup client
and the workgroup key server.
16. The system of claim 12, wherein the first encryption key and
the second encryption key comprise symmetric encryption keys, and
wherein the first workgroup client does not have access to the
second encryption key, and wherein the second workgroup client does
not have access to the first encryption key.
17. The system of claim 12, wherein the first encrypted message and
the second encrypted message each include an identification of the
first workgroup client and the second workgroup client.
18. The system of claim 12, wherein the first encrypted message and
the second encrypted message are transmitted by the workgroup key
server in response to the request from the first workgroup client
to initiate the communication session with the second workgroup
client.
19. The system of claim 12, wherein the first encrypted message and
the second encrypted message further include at least one of a
timestamp associated with creation of the workgroup key and a
version number associated with the workgroup key.
20. The system of claim 19, wherein the timestamp and/or the
version number is usable to determine whether the workgroup key is
expired.
21. The system of claim 12, wherein the workgroup communication
comprises a plurality of share headers that are associated with a
plurality of shares.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of U.S. patent
application Ser. No. 14/181,257 filed Feb. 14, 2014, which claims
the benefit of U.S. patent application Ser. No. 12/391,025 filed
Feb. 23, 2009, now U.S. Pat. No. 8,656,167, which claims the
benefit of U.S. Provisional Patent Application Nos. 61/066,699,
entitled "Systems and Methods for Secure Workgroup Management"
filed Feb. 22, 2008, and 61/147,961, entitled "Workgroup Key
Management and Distribution" filed Jan. 28, 2009. Each of these
prior applications are incorporated by reference herein in their
entireties.
FIELD OF THE INVENTION
[0002] The present invention relates in general to improved systems
and methods for securing data in motion (i.e., data being
transferred from one location to another) within a workgroup. The
systems and methods described herein may be used in conjunction
with other systems and methods described in commonly-owned U.S.
Pat. No. 7,391,865 and commonly-owned U.S. patent application Ser.
No. 10/458,928, filed Jun. 11, 2003, Ser. No. 11/258,839, filed
Oct. 25, 2005, Ser. No. 11/602,667, filed Nov. 20, 2006, Ser. No.
11/983,355, filed Nov. 7, 2007, Ser. No. 11/999,575, filed Dec. 5,
2007, Ser. No. 12/209,703, filed Sep. 12, 2008, and Ser. No.
12/349,897, filed Jan. 7, 2009, all of which are hereby
incorporated by reference herein in their entireties.
BACKGROUND OF THE INVENTION
[0003] In today's society, individuals and businesses conduct an
ever-increasing amount of activities on and over computer systems.
These computer systems, including proprietary and non-proprietary
computer networks, are often storing, archiving, and transmitting
all types of sensitive information. Thus, an ever-increasing need
exists for ensuring data stored and transmitted over these systems
cannot be read or otherwise compromised.
[0004] One common solution for securing computer systems is to
provide login and password functionality. However, password
management has proven to be quite costly with a large percentage of
help desk calls relating to password issues. Moreover, passwords
provide little security in that they are generally stored in a file
susceptible to inappropriate access, through, for example,
brute-force attacks.
[0005] Another solution for securing computer systems is to provide
cryptographic infrastructures. Cryptography, in general, refers to
protecting data by transforming, or encrypting, it into an
unreadable format. Only those who possess the key(s) to the
encryption can decrypt the data into a useable format. Cryptography
may be used to identify users, e.g., authentication, to allow
access privileges, e.g., authorization, to create digital
certificates and signatures, and the like. One popular cryptography
system is a public key system that uses two keys, a public key
known to everyone and a private key known only to the individual or
business owner thereof. Generally, the data encrypted with one key
is decrypted with the other and neither key is recreatable from the
other.
[0006] Unfortunately, even the foregoing typical public-key
cryptographic systems are still highly reliant on the user for
security. For example, cryptographic systems issue the private key
to the user, for example, through the user's browser.
Unsophisticated users then generally store the private key on a
hard drive accessible to others through an open computer system,
such as, for example, the Internet. On the other hand, users may
choose poor names for files containing their private key, such as,
for example, "key." The result of the foregoing and other acts is
to allow the key or keys to be susceptible to compromise.
[0007] Traditional solutions for securing data in motion also fail
to provide robust and secure workgroup support. For example, the
members of a workgroup may wish to communicate securely (e.g., in a
private and authenticated manner) with other workgroup members over
one or more secure channels. Typical secure workgroup communication
protocols based on pre-shared workgroup encryption keys, public key
broadcast encryption, and the like often become unstable and
insecure because of insecure and inefficient management and
distribution of the shared workgroup key. In addition, these secure
workgroup communication protocols generally include only limited
workgroup client revocation support. For example, the communication
privileges of any one workgroup member generally cannot be
efficiently revoked, for example, after compromise of the member's
identity or shared workgroup key, or after the workgroup member
leaves a workgroup. Moreover, with traditional approaches, there is
generally no way to quickly and efficiently renew a workgroup
security mechanism either on-demand, periodically, or automatically
after the communication privileges of any one workgroup member has
been revoked (or the workgroup member leaves the workgroup).
SUMMARY OF THE INVENTION
[0008] Based on the foregoing, a need exists to provide a more
robust and secure workgroup security scheme for use with data in
motion solutions.
[0009] In some embodiments, a workgroup management module is
provided to manage workgroup encryption keys. The module may be
integrated with third-party user authentication, user logon, or
directory access services, such as Microsoft's.RTM. Active
Directory (AD) directory service. The directory service may enforce
security policies for users (and groups of users), as well as
manage and verify workgroup membership and track workgroup and user
activities.
[0010] The workgroup management module may be integrated with any
of the secure data parsers described in the above-referenced U.S.
patent and patent applications in order to secure data in motion
between any two or more end points (e.g., clients or services)
belonging to the same workgroup. In some embodiments, users are
authenticated through the verification of a shared secret. For
example, Digest Authentication may be used to transform a user's
ASCII password into a cryptographic key. The client device may then
request a challenge value, which is encrypted using the
password-based key. The resulting ciphertext may then be
transmitted to the authentication server. In response to receiving
the ciphertext, the authentication server may perform the same
encryption on the challenge value (using a stored copy of the
user's password-based key) and verify that the received ciphertext
and the result of the server's encryption are a match. If there is
a match, the client may be authenticated. Otherwise, the
authentication request may be denied.
[0011] After a user is authenticated, further requests for services
and communications on the network may be handled by a
Kerberos-based subsystem of the authentication server. Users or
client devices may be supplied a Ticket Granting Ticket (TGT) that
serves as a token to be given to a Key Distribution Center (KDC)
whenever a secure service or secure communication with another
workgroup member is desired. In some embodiments, the TGT may
include a block or string of data indicative of one or more of the
identity of the recipient, a timestamp, and any other credentials.
The TGT may be encrypted under the KDC's Master Key so that only
the KDC may read its contents.
[0012] To communication securely with a service (e.g., email or web
server), a client may pass the TGT to the KDC and request a Service
Ticket (ST). If the TGT is valid, the KDC may return two STs to the
client, each containing the credentials of the parties involved in
the communication, a timestamp, and a unique and fresh Session Key
(SK) to be used as a temporary shared key between both parties for
encryption. One of the STs may be encrypted using the shared
password-based key between the user and the KDC, and the other ST
may be encrypted using the shared password-based key between the
service being accessed and the KDC. The ST encrypted for the client
making the request may immediately be decrypted and the session key
uncovered. The user may then send the second ST and a message
encrypted using the SK to the targeted service. The service may
then decrypt the ST with its password-based key to obtain the SK,
and subsequently decrypt the message sent by the user. Through this
process, the client and the service may now share the SK.
[0013] The SK may then be used as a Workgroup Key (WK) for use with
the secure data parser. The WK may be stored locally to a client's
KeyStore. The WK may also be used to wrap internally created
session keys, including the Encryption Session Key (ESK) and the
MAC Session Key (MK). After being wrapped with the WK, the
ciphertexts may be securely shared among each header generated by
the secure data parser, where a single share of each wrapped key is
stored with each header. Accessing the ESK or MK now may require
obtaining the WK and some minimum quorum of shares sufficient to
restore the wrapped ESK and MK ciphertexts.
[0014] In some embodiments, the WK may be used to wrap an
internally generated ESK. Once wrapped with the WK, the ciphertext
may be again wrapped with a freshly generated Key Encrypting Key
(KEK), resulting in an ESK that has been doubly wrapped and that
can only be recovered with knowledge of both the WK and the KEK.
The KEK may be securely shared among each header generated by the
secure data parser, and the doubly wrapped ESK may be stored within
each header. Recovering the ESK may now require obtaining WK and
some minimum quorum of shares sufficient to rebuild the KEK.
[0015] In some embodiments, online key updates are supported. Each
time a client wishes to update its key (or check the availability
of an update), the client may interact with an online key server.
This online key server may then distribute and share key material
according to a workgroup security policy.
[0016] In some embodiments, online key updates may be made
available on-demand, periodically on some schedule defined by the
workgroup security policy, or automatically after some event (e.g.,
after a client's communication privileges are revoked or a client
leaves a workgroup). The key update system may be managed by a
Workgroup Authority (WA), which may control workgroup membership
for multiple client devices and users. Each client or user in the
system may be initially provisioned with a public/private keypair.
Public keys may be registered with the WA, which may also record or
store the public keys. Alternatively, in some embodiments, a
symmetric encryption scheme may be used where each client or user
in the system is initially provisioned with a secret key instead of
a public/private keypair. Secret keys may be registered with the
WA, which may also record or store the secret keys. The WA (or some
other workgroup key server) may provide each device with the key
server's public key certificate, which has been signed by a trusted
Certificate Authority (CA).
[0017] To initiate an outgoing connection or receive an incoming
connection, each client may contact its WA, which may, in some
embodiments, interface with a third-party authentication or user
logon service (e.g., an Active Directory server) to determine the
client's workgroup membership. The client may then proves its
identity to the WA using public-key or secret key techniques. The
current WK may then be encrypted using a public-key or secret key
encryption scheme such that a receiving client can decrypt the
resulting ciphertext to obtain the current WK. The resulting
ciphertext may also be signed by the key server (using the signing
key corresponding to its certified public key) and transmitted to
the requesting client.
[0018] In some embodiments, key updates may be supported even when
the key server cannot be reached by a client (i.e., the client is
untethered or partially untethered). Renewability may still be
achieved by incorporating a mechanism to periodically update the
shared workgroup key. On a periodic schedule, key updates may be
initiated by the key server, which may interface with a third-party
authentication or user logon service to determine group membership.
Each key update may contain a fresh WK and its identifier. The WK
may be encrypted using a public-key broadcast encryption scheme
such that only the current workgroup members can decrypt the
resulting ciphertext. The resulting ciphertext may then be signed
by the key server (using the signing key corresponding to its
certified public key) and transmitted to the non-revoked devices
via a semi-trusted channel (e.g., a website). For example, when a
client is prepared to go offline, the key server can pre-provision
the client with key updates for a limited number of future time
periods. Additionally or alternatively, for clients with limited
network access, key revocation and update messages can be posted to
a highly-available location, e.g., a TLS-secured public
website.
[0019] To join a workgroup, in some embodiments, a client is first
registered with the WA, and the client is then provisioned with a
secret key. The WA may store the client's identity and secret key
in a secure location (e.g., in an encrypted lookup table or
keystore).
[0020] To initiate connections, in some embodiments, a client may
connect to the WA using its secret key and request the WK. The WA
may look up the client and use the stored key to decrypt the
message. It may then responds with the WK encrypted with the
client's secret key. The client may now use the WK to initiate a
connection to another client in the workgroup. In some embodiments,
the WA also indicates to the client an approximate duration of
validity for the WK. Security policies in force on the client may
require the client to contact the WA after key expiration for a key
update (but the client may also check for key updates before key
expiration if desired). When receiving a connection, security
policies in force on the client may require a fresh and unexpired
WK, verifying the status of the WK by the WA if necessary.
[0021] To revoke the communication privileges of a single client
within a workgroup, the WA may refuse further key updates to the
revoked client. A compromised client, therefore, may only have
communication access to the workgroup during the period of time
that the current WK is valid. Revocation may only affect new
connections, or both new connections and existing connections (by
terminating stale connections or forcing reconnection when a
connection exceeds some system-defined length of time or number of
connections).
[0022] To initiate a connection with another workgroup member, in
some embodiments, the initiator may send the headers generated by
the secure data parser to a recipient workgroup member. The headers
may include one or more of the workgroup key, a workgroup key
identifier, and a workgroup key version number. The recipient
workgroup member may then check the workgroup key identifier to
verify that the identifier is the correct identifier used for the
current workgroup. The recipient workgroup member may also check
the workgroup key version number to verify that the version number
is the same as the recipient workgroup member's current workgroup
key version number (and optionally if the current time is greater
than the workgroup key refresh alarm time). If the workgroup key
identifier is valid and the workgroup key version numbers are
identical (and optionally if the current time is not greater than
the workgroup key refresh alarm time), then the recipient workgroup
member may report a successful connection attempt.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The present invention is described in more detail below in
connection with the attached drawings, which are meant to
illustrate and not to limit the invention, and in which:
[0024] FIG. 1 illustrates a block diagram of a cryptographic
system, according to aspects of an embodiment of the invention;
[0025] FIG. 2 illustrates a block diagram of the trust engine of
FIG. 1, according to aspects of an embodiment of the invention;
[0026] FIG. 3 illustrates a block diagram of the transaction engine
of FIG. 2, according to aspects of an embodiment of the
invention;
[0027] FIG. 4 illustrates a block diagram of the depository of FIG.
2, according to aspects of an embodiment of the invention;
[0028] FIG. 5 illustrates a block diagram of the authentication
engine of FIG. 2, according to aspects of an embodiment of the
invention;
[0029] FIG. 6 illustrates a block diagram of the cryptographic
engine of FIG. 2, according to aspects of an embodiment of the
invention;
[0030] FIG. 7 is a block diagram of an illustrative data in motion
system in accordance with one embodiment of the present
invention;
[0031] FIG. 8 is a block diagram of another illustrative data in
motion system in accordance with one embodiment of the present
invention;
[0032] FIGS. 9A and 9B are simplified and illustrative process flow
diagrams for header generation and data splitting for data in
motion, that may be used in any suitable combination, with any
suitable additions, deletions, or modifications in accordance with
one embodiment of the present invention;
[0033] FIG. 10 is a simplified block diagram of an illustrative
share format, that may be used in any suitable combination, with
any suitable additions, deletions, or modifications in accordance
with one embodiment of the present invention;
[0034] FIG. 11 is a simplified protocol illustrating the message
sequence for authenticating a client in a workgroup in accordance
with one embodiment of the present invention;
[0035] FIG. 12 is a simplified protocol illustrating the message
sequence for obtaining service tickets in a workgroup in accordance
with one embodiment of the present invention;
[0036] FIG. 13 is a simplified protocol illustrating the message
sequence for using a workgroup key to secure data in motion in
accordance with one embodiment of the present invention;
[0037] FIG. 14 is a simplified protocol illustrating the message
sequence for kernel and user space interaction in accordance with
one embodiment of the present invention;
[0038] FIG. 15 is a simplified block diagram of the initial setup
of Workgroup Authorities within a domain in accordance with one
embodiment of the present invention;
[0039] FIG. 16 is a simplified protocol illustrating the connection
sequence for two clients within a workgroup in accordance with one
embodiment of the present invention;
[0040] FIG. 17 is an illustrative process flow diagram for joining
a workgroup in accordance with one embodiment of the present
invention;
[0041] FIGS. 18A, 18B, and 18C are illustrative process flow
diagrams for initiating a connection between two workgroup clients
in accordance with one embodiment of the present invention;
[0042] FIG. 19 is an illustrative process flow diagram for revoking
a client's communication privileges within a workgroup in
accordance with one embodiment of the present invention; and
[0043] FIG. 20 is an illustrative process flow diagram for updating
a workgroup key in accordance with one embodiment of the present
invention.
DETAILED DESCRIPTION
[0044] The present invention provides a cryptographic system where
one or more secure servers, or a trust engine, stores cryptographic
keys and user authentication data. Users may access the
functionality of conventional cryptographic systems through network
access to the trust engine, however, the trust engine does not
release actual keys and other authentication data and therefore,
the keys and data remain secure. This server-centric storage of
keys and authentication data provides for user-independent
security, portability, availability, and straightforwardness.
[0045] Because users can be confident in, or trust, the
cryptographic system to perform user and document authentication
and other cryptographic functions, a wide variety of functionality
may be incorporated into the system. For example, the trust engine
provider can ensure against agreement repudiation by, for example,
authenticating the agreement participants, digitally signing the
agreement on behalf of or for the participants, and storing a
record of the agreement digitally signed by each participant. In
addition, the cryptographic system may monitor agreements and
determine to apply varying degrees of authentication, based on, for
example, price, user, vendor, geographic location, place of use, or
the like.
[0046] To facilitate a complete understanding of the invention, the
remainder of the detailed description describes the invention with
reference to the figures, wherein like elements are referenced with
like numerals throughout.
[0047] FIG. 1 illustrates a block diagram of a cryptographic system
100, according to aspects of an embodiment of the invention. As
shown in FIG. 1, the cryptographic system 100 includes a user
system 105, a trust engine 110, a certificate authority 115, and a
vendor system 120, communicating through a communication link
125.
[0048] According to one embodiment of the invention, the user
system 105 comprises a conventional general-purpose computer having
one or more microprocessors, such as, for example, an Intel-based
processor. Moreover, the user system 105 includes an appropriate
operating system, such as, for example, an operating system capable
of including graphics or windows, such as Windows, Unix, Linux, or
the like. As shown in FIG. 1, the user system 105 may include a
biometric device 107. The biometric device 107 may advantageously
capture a user's biometric and transfer the captured biometric to
the trust engine 110. According to one embodiment of the invention,
the biometric device may advantageously comprise a device having
attributes and features similar to those disclosed in U.S. Pat. No.
6,856,383, entitled "RELIEF OBJECT IMAGE GENERATOR," U.S. patent
application Ser. No. 09/558,634, filed on Apr. 26, 2000, entitled
"IMAGING DEVICE FOR A RELIEF OBJECT AND SYSTEM AND METHOD OF USING
THE IMAGE DEVICE," U.S. Pat. No. 6,631,201, entitled "RELIEF OBJECT
SENSOR ADAPTOR," and U.S. patent application Ser. No. 09/477,943,
filed on Jan. 5, 2000, entitled "PLANAR OPTICAL IMAGE SENSOR AND
SYSTEM FOR GENERATING AN ELECTRONIC IMAGE OF A RELIEF OBJECT FOR
FINGERPRINT READING," all of which are owned by the instant
assignee, and all of which are hereby incorporated by reference
herein.
[0049] In addition, the user system 105 may connect to the
communication link 125 through a conventional service provider,
such as, for example, a dial up, digital subscriber line (DSL),
cable modem, fiber connection, or the like. According to another
embodiment, the user system 105 connects the communication link 125
through network connectivity such as, for example, a local or wide
area network. According to one embodiment, the operating system
includes a TCP/IP stack that handles all incoming and outgoing
message traffic passed over the communication link 125.
[0050] Although the user system 105 is disclosed with reference to
the foregoing embodiments, the invention is not intended to be
limited thereby. Rather, a skilled artisan will recognize from the
disclosure herein, a wide number of alternatives embodiments of the
user system 105, including almost any computing device capable of
sending or receiving information from another computer system. For
example, the user system 105 may include, but is not limited to, a
computer workstation, an interactive television, an interactive
kiosk, a personal mobile computing device, such as a digital
assistant, mobile or cellular telephone, laptop, or the like, a
wireless communications device, a smartcard, an embedded computing
device, or the like, which can interact with the communication link
125. In such alternative systems, the operating systems will likely
differ and be adapted for the particular device. However, according
to one embodiment, the operating systems advantageously continue to
provide the appropriate communications protocols needed to
establish communication with the communication link 125.
[0051] FIG. 1 illustrates the trust engine 110. According to one
embodiment, the trust engine 110 comprises one or more secure
servers for accessing and storing sensitive information, which may
be any type or form of data, such as, but not limited to text,
audio, video, user authentication data and public and private
cryptographic keys. According to one embodiment, the authentication
data includes data designed to uniquely identify a user of the
cryptographic system 100. For example, the authentication data may
include a user identification number, one or more biometrics, and a
series of questions and answers generated by the trust engine 110
or the user, but answered initially by the user at enrollment. The
foregoing questions may include demographic data, such as place of
birth, address, anniversary, or the like, personal data, such as
mother's maiden name, favorite ice cream, or the like, or other
data designed to uniquely identify the user. The trust engine 110
compares a user's authentication data associated with a current
transaction, to the authentication data provided at an earlier
time, such as, for example, during enrollment. The trust engine 110
may advantageously require the user to produce the authentication
data at the time of each transaction, or, the trust engine 110 may
advantageously allow the user to periodically produce
authentication data, such as at the beginning of a string of
transactions or the logging onto a particular vendor website.
[0052] According to the embodiment where the user produces
biometric data, the user provides a physical characteristic, such
as, but not limited to, facial scan, hand scan, ear scan, iris
scan, retinal scan, vascular pattern, DNA, a fingerprint, writing
or speech, to the biometric device 107. The biometric device
advantageously produces an electronic pattern, or biometric, of the
physical characteristic. The electronic pattern is transferred
through the user system 105 to the trust engine 110 for either
enrollment or authentication purposes.
[0053] Once the user produces the appropriate authentication data
and the trust engine 110 determines a positive match between that
authentication data (current authentication data) and the
authentication data provided at the time of enrollment (enrollment
authentication data), the trust engine 110 provides the user with
complete cryptographic functionality. For example, the properly
authenticated user may advantageously employ the trust engine 110
to perform hashing, digitally signing, encrypting and decrypting
(often together referred to only as encrypting), creating or
distributing digital certificates, and the like. However, the
private cryptographic keys used in the cryptographic functions will
not be available outside the trust engine 110, thereby ensuring the
integrity of the cryptographic keys.
[0054] According to one embodiment, the trust engine 110 generates
and stores cryptographic keys. According to another embodiment, at
least one cryptographic key is associated with each user. Moreover,
when the cryptographic keys include public-key technology, each
private key associated with a user is generated within, and not
released from, the trust engine 110. Thus, so long as the user has
access to the trust engine 110, the user may perform cryptographic
functions using his or her private or public key. Such remote
access advantageously allows users to remain completely mobile and
access cryptographic functionality through practically any Internet
connection, such as cellular and satellite phones, kiosks, laptops,
hotel rooms and the like.
[0055] According to another embodiment, the trust engine 110
performs the cryptographic functionality using a key pair generated
for the trust engine 110. According to this embodiment, the trust
engine 110 first authenticates the user, and after the user has
properly produced authentication data matching the enrollment
authentication data, the trust engine 110 uses its own
cryptographic key pair to perform cryptographic functions on behalf
of the authenticated user.
[0056] A skilled artisan will recognize from the disclosure herein
that all the cryptographic keys may advantageously include one or
more of symmetric encryption keys (e.g., private keys) and
asymmetric encryption keys (e.g., public/private keypairs). In
addition, a skilled artisan will recognize from the disclosure
herein that the foregoing keys may be implemented with a wide
number of algorithms available from commercial technologies, such
as, for example, RSA, ELGAMAL, or the like. When an asymmetric
cryptographic scheme is described herein, this scheme may be
substituted with a symmetric scheme, and vice versa.
[0057] FIG. 1 also illustrates the certificate authority 115.
According to one embodiment, the certificate authority 115 may
advantageously comprise a trusted third-party organization or
company that issues digital certificates, such as, for example,
VeriSign, Baltimore, Entrust, or the like. The trust engine 110 may
advantageously transmit requests for digital certificates, through
one or more conventional digital certificate protocols, such as,
for example, PKCS10, to the certificate authority 115. In response,
the certificate authority 115 will issue a digital certificate in
one or more of a number of differing protocols, such as, for
example, PKCS7. According to one embodiment of the invention, the
trust engine 110 requests digital certificates from several or all
of the prominent certificate authorities 115 such that the trust
engine 110 has access to a digital certificate corresponding to the
certificate standard of any requesting party.
[0058] According to another embodiment, the trust engine 110
internally performs certificate issuances. In this embodiment, the
trust engine 110 may access a certificate system for generating
certificates and/or may internally generate certificates when they
are requested, such as, for example, at the time of key generation
or in the certificate standard requested at the time of the
request. The trust engine 110 will be disclosed in greater detail
below.
[0059] FIG. 1 also illustrates the vendor system 120. According to
one embodiment, the vendor system 120 advantageously comprises a
Web server. Typical Web servers generally serve content over the
Internet using one of several internet markup languages or document
format standards, such as the Hyper-Text Markup Language (HTML) or
the Extensible Markup Language (XML). The Web server accepts
requests from browsers like Netscape and Internet Explorer and then
returns the appropriate electronic documents. A number of server or
client-side technologies can be used to increase the power of the
Web server beyond its ability to deliver standard electronic
documents. For example, these technologies include Common Gateway
Interface (CGI) scripts, Secure Sockets Layer (SSL) security, and
Active Server Pages (ASPs). The vendor system 120 may
advantageously provide electronic content relating to commercial,
personal, educational, or other transactions.
[0060] Although the vendor system 120 is disclosed with reference
to the foregoing embodiments, the invention is not intended to be
limited thereby. Rather, a skilled artisan will recognize from the
disclosure herein that the vendor system 120 may advantageously
comprise any of the devices described with reference to the user
system 105 or combination thereof.
[0061] FIG. 1 also illustrates the communication link 125
connecting the user system 105, the trust engine 110, the
certificate authority 115, and the vendor system 120. According to
one embodiment, the communication link 125 preferably comprises the
Internet. The Internet, as used throughout this disclosure is a
global network of computers. The structure of the Internet, which
is well known to those of ordinary skill in the art, includes a
network backbone with networks branching from the backbone. These
branches, in turn, have networks branching from them, and so on.
Routers move information packets between network levels, and then
from network to network, until the packet reaches the neighborhood
of its destination. From the destination, the destination network's
host directs the information packet to the appropriate terminal, or
node. In one advantageous embodiment, the Internet routing hubs
comprise domain name system (DNS) servers using Transmission
Control Protocol/Internet Protocol (TCP/IP) as is well known in the
art. The routing hubs connect to one or more other routing hubs via
high-speed communication links.
[0062] One popular part of the Internet is the World Wide Web. The
World Wide Web contains different computers, which store documents
capable of displaying graphical and textual information. The
computers that provide information on the World Wide Web are
typically called "websites." A website is defined by an Internet
address that has an associated electronic page. The electronic page
can be identified by a Uniform Resource Locator (URL). Generally,
an electronic page is a document that organizes the presentation of
text, graphical images, audio, video, and so forth.
[0063] Although the communication link 125 is disclosed in terms of
its preferred embodiment, one of ordinary skill in the art will
recognize from the disclosure herein that the communication link
125 may include a wide range of interactive communications links.
For example, the communication link 125 may include interactive
television networks, telephone networks, wireless data transmission
systems, two-way cable systems, customized private or public
computer networks, interactive kiosk networks, automatic teller
machine networks, direct links, satellite or cellular networks, and
the like.
[0064] FIG. 2 illustrates a block diagram of the trust engine 110
of FIG. 1 according to aspects of an embodiment of the invention.
As shown in FIG. 2, the trust engine 110 includes a transaction
engine 205, a depository 210, an authentication engine 215, and a
cryptographic engine 220. According to one embodiment of the
invention, the trust engine 110 also includes mass storage 225. As
further shown in FIG. 2, the transaction engine 205 communicates
with the depository 210, the authentication engine 215, and the
cryptographic engine 220, along with the mass storage 225. In
addition, the depository 210 communicates with the authentication
engine 215, the cryptographic engine 220, and the mass storage 225.
Moreover, the authentication engine 215 communicates with the
cryptographic engine 220. According to one embodiment of the
invention, some or all of the foregoing communications may
advantageously comprise the transmission of XML documents to IP
addresses that correspond to the receiving device. As mentioned in
the foregoing, XML documents advantageously allow designers to
create their own customized document tags, enabling the definition,
transmission, validation, and interpretation of data between
applications and between organizations. Moreover, some or all of
the foregoing communications may include conventional SSL
technologies.
[0065] According to one embodiment, the transaction engine 205
comprises a data routing device, such as a conventional Web server
available from Netscape, Microsoft, Apache, or the like. For
example, the Web server may advantageously receive incoming data
from the communication link 125. According to one embodiment of the
invention, the incoming data is addressed to a front-end security
system for the trust engine 110. For example, the front-end
security system may advantageously include a firewall, an intrusion
detection system searching for known attack profiles, and/or a
virus scanner. After clearing the front-end security system, the
data is received by the transaction engine 205 and routed to one of
the depository 210, the authentication engine 215, the
cryptographic engine 220, and the mass storage 225. In addition,
the transaction engine 205 monitors incoming data from the
authentication engine 215 and cryptographic engine 220, and routes
the data to particular systems through the communication link 125.
For example, the transaction engine 205 may advantageously route
data to the user system 105, the certificate authority 115, or the
vendor system 120.
[0066] According to one embodiment, the data is routed using
conventional HTTP routing techniques, such as, for example,
employing URLs or Uniform Resource Indicators (URIs). URIs are
similar to URLs, however, URIs typically indicate the source of
files or actions, such as, for example, executables, scripts, and
the like. Therefore, according to the one embodiment, the user
system 105, the certificate authority 115, the vendor system 120,
and the components of the trust engine 210, advantageously include
sufficient data within communication URLs or URIs for the
transaction engine 205 to properly route data throughout the
cryptographic system.
[0067] Although the data routing is disclosed with reference to its
preferred embodiment, a skilled artisan will recognize a wide
number of possible data routing solutions or strategies. For
example, XML or other data packets may advantageously be unpacked
and recognized by their format, content, or the like, such that the
transaction engine 205 may properly route data throughout the trust
engine 110. Moreover, a skilled artisan will recognize that the
data routing may advantageously be adapted to the data transfer
protocols conforming to particular network systems, such as, for
example, when the communication link 125 comprises a local
network.
[0068] According to yet another embodiment of the invention, the
transaction engine 205 includes conventional SSL encryption
technologies, such that the foregoing systems may authenticate
themselves, and vise-versa, with transaction engine 205, during
particular communications. As will be used throughout this
disclosure, the term "1/2 SSL" refers to communications where a
server but not necessarily the client, is SSL authenticated, and
the term "FULL SSL" refers to communications where the client and
the server are SSL authenticated. When the instant disclosure uses
the term "SSL", the communication may comprise 1/2 or FULL SSL.
[0069] As the transaction engine 205 routes data to the various
components of the cryptographic system 100, the transaction engine
205 may advantageously create an audit trail. According to one
embodiment, the audit trail includes a record of at least the type
and format of data routed by the transaction engine 205 throughout
the cryptographic system 100. Such audit data may advantageously be
stored in the mass storage 225.
[0070] FIG. 2 also illustrates the depository 210. According to one
embodiment, the depository 210 comprises one or more data storage
facilities, such as, for example, a directory server, a database
server, or the like. As shown in FIG. 2, the depository 210 stores
cryptographic keys and enrollment authentication data. The
cryptographic keys may advantageously correspond to the trust
engine 110 or to users of the cryptographic system 100, such as the
user or vendor. The enrollment authentication data may
advantageously include data designed to uniquely identify a user,
such as, user ID, passwords, answers to questions, biometric data,
or the like. This enrollment authentication data may advantageously
be acquired at enrollment of a user or another alternative later
time. For example, the trust engine 110 may include periodic or
other renewal or reissue of enrollment authentication data.
[0071] According to one embodiment, the communication from the
transaction engine 205 to and from the authentication engine 215
and the cryptographic engine 220 comprises secure communication,
such as, for example conventional SSL technology. In addition, as
mentioned in the foregoing, the data of the communications to and
from the depository 210 may be transferred using URLs, URIs, HTTP
or XML documents, with any of the foregoing advantageously having
data requests and formats embedded therein.
[0072] As mentioned above, the depository 210 may advantageously
comprises a plurality of secure data storage facilities. In such an
embodiment, the secure data storage facilities may be configured
such that a compromise of the security in one individual data
storage facility will not compromise the cryptographic keys or the
authentication data stored therein. For example, according to this
embodiment, the cryptographic keys and the authentication data are
mathematically operated on so as to statistically and substantially
randomize the data stored in each data storage facility. According
to one embodiment, the randomization of the data of an individual
data storage facility renders that data undecipherable. Thus,
compromise of an individual data storage facility produces only a
randomized undecipherable number and does not compromise the
security of any cryptographic keys or the authentication data as a
whole.
[0073] FIG. 2 also illustrates the trust engine 110 including the
authentication engine 215. According to one embodiment, the
authentication engine 215 comprises a data comparator configured to
compare data from the transaction engine 205 with data from the
depository 210. For example, during authentication, a user supplies
current authentication data to the trust engine 110 such that the
transaction engine 205 receives the current authentication data. As
mentioned in the foregoing, the transaction engine 205 recognizes
the data requests, preferably in the URL or URI, and routes the
authentication data to the authentication engine 215. Moreover,
upon request, the depository 210 forwards enrollment authentication
data corresponding to the user to the authentication engine 215.
Thus, the authentication engine 215 has both the current
authentication data and the enrollment authentication data for
comparison.
[0074] According to one embodiment, the communications to the
authentication engine comprise secure communications, such as, for
example, SSL technology. Additionally, security can be provided
within the trust engine 110 components, such as, for example,
super-encryption using public key technologies. For example,
according to one embodiment, the user encrypts the current
authentication data with the public key of the authentication
engine 215. In addition, the depository 210 also encrypts the
enrollment authentication data with the public key of the
authentication engine 215. In this way, only the authentication
engine's private key can be used to decrypt the transmissions.
[0075] As shown in FIG. 2, the trust engine 110 also includes the
cryptographic engine 220. According to one embodiment, the
cryptographic engine comprises a cryptographic handling module,
configured to advantageously provide conventional cryptographic
functions, such as, for example, public-key infrastructure (PKI)
functionality. For example, the cryptographic engine 220 may
advantageously issue public and private keys for users of the
cryptographic system 100. In this manner, the cryptographic keys
are generated at the cryptographic engine 220 and forwarded to the
depository 210 such that at least the private cryptographic keys
are not available outside of the trust engine 110. According to
another embodiment, the cryptographic engine 220 randomizes and
splits at least the private cryptographic key data, thereby storing
only the randomized split data. Similar to the splitting of the
enrollment authentication data, the splitting process ensures the
stored keys are not available outside the cryptographic engine 220.
According to another embodiment, the functions of the cryptographic
engine can be combined with and performed by the authentication
engine 215.
[0076] According to one embodiment, communications to and from the
cryptographic engine include secure communications, such as SSL
technology. In addition, XML documents may advantageously be
employed to transfer data and/or make cryptographic function
requests.
[0077] FIG. 2 also illustrates the trust engine 110 having the mass
storage 225. As mentioned in the foregoing, the transaction engine
205 keeps data corresponding to an audit trail and stores such data
in the mass storage 225. Similarly, according to one embodiment of
the invention, the depository 210 keeps data corresponding to an
audit trail and stores such data in the mass storage device 225.
The depository audit trail data is similar to that of the
transaction engine 205 in that the audit trail data comprises a
record of the requests received by the depository 210 and the
response thereof. In addition, the mass storage 225 may be used to
store digital certificates having the public key of a user
contained therein.
[0078] Although the trust engine 110 is disclosed with reference to
its preferred and alternative embodiments, the invention is not
intended to be limited thereby. Rather, a skilled artisan will
recognize in the disclosure herein, a wide number of alternatives
for the trust engine 110. For example, the trust engine 110, may
advantageously perform only authentication, or alternatively, only
some or all of the cryptographic functions, such as data encryption
and decryption. According to such embodiments, one of the
authentication engine 215 and the cryptographic engine 220 may
advantageously be removed, thereby creating a more straightforward
design for the trust engine 110. In addition, the cryptographic
engine 220 may also communicate with a certificate authority such
that the certificate authority is embodied within the trust engine
110. According to yet another embodiment, the trust engine 110 may
advantageously perform authentication and one or more cryptographic
functions, such as, for example, digital signing.
[0079] FIG. 3 illustrates a block diagram of the transaction engine
205 of FIG. 2, according to aspects of an embodiment of the
invention. According to this embodiment, the transaction engine 205
comprises an operating system 305 having a handling thread and a
listening thread. The operating system 305 may advantageously be
similar to those found in conventional high volume servers, such
as, for example, Web servers available from Apache. The listening
thread monitors the incoming communication from one of the
communication link 125, the authentication engine 215, and the
cryptographic engine 220 for incoming data flow. The handling
thread recognizes particular data structures of the incoming data
flow, such as, for example, the foregoing data structures, thereby
routing the incoming data to one of the communication link 125, the
depository 210, the authentication engine 215, the cryptographic
engine 220, or the mass storage 225. As shown in FIG. 3, the
incoming and outgoing data may advantageously be secured through,
for example, SSL technology.
[0080] FIG. 4 illustrates a block diagram of the depository 210 of
FIG. 2 according to aspects of an embodiment of the invention.
According to this embodiment, the depository 210 comprises one or
more lightweight directory access protocol (LDAP) servers. LDAP
directory servers are available from a wide variety of
manufacturers such as Netscape, ISO, Microsoft, and others. FIG. 4
also shows that the directory server preferably stores data 405
corresponding to the cryptographic keys and data 410 corresponding
to the enrollment authentication data. According to one embodiment,
the depository 210 comprises a single logical memory structure
indexing authentication data and cryptographic key data to a unique
user ID. The single logical memory structure preferably includes
mechanisms to ensure a high degree of trust, or security, in the
data stored therein. For example, the physical location of the
depository 210 may advantageously include a wide number of
conventional security measures, such as limited employee access,
modern surveillance systems, and the like. In addition to, or in
lieu of, the physical securities, the computer system or server may
advantageously include software solutions to protect the stored
data. For example, the depository 210 may advantageously create and
store data 415 corresponding to an audit trail of actions taken. In
addition, the incoming and outgoing communications may
advantageously be encrypted with public key encryption coupled with
conventional SSL technologies.
[0081] According to another embodiment, the depository 210 may
include distinct and physically separated data storage facilities.
For example, depository 210 may include more than one physical
storage device (e.g., tape drive, hard disk drive, optical drive,
or any combination thereof) housed in geographically separated
locations.
[0082] FIG. 5 illustrates a block diagram of the authentication
engine 215 of FIG. 2 according to aspects of an embodiment of the
invention. Similar to the transaction engine 205 of FIG. 3, the
authentication engine 215 comprises an operating system 505 having
at least a listening and a handling thread of a modified version of
a conventional Web server, such as, for example, Web servers
available from Apache. As shown in FIG. 5, the authentication
engine 215 includes access to at least one private key 510. The
private key 510 may advantageously be used for example, to decrypt
data from the transaction engine 205 or the depository 210, which
was encrypted with a corresponding public key of the authentication
engine 215.
[0083] FIG. 5 also illustrates the authentication engine 215
comprising a comparator 515, a data splitting module 520, and a
data assembling module 525. According to an embodiment of the
invention, the comparator 515 includes technology capable of
comparing potentially complex patterns related to the foregoing
biometric authentication data. The technology may include hardware,
software, or combined solutions for pattern comparisons, such as,
for example, those representing finger print patterns or voice
patterns. In addition, according to one embodiment, the comparator
515 of the authentication engine 215 may advantageously compare
conventional hashes of documents in order to render a comparison
result. According to one embodiment of the invention, the
comparator 515 includes the application of heuristics 530 to the
comparison. The heuristics 530 may advantageously address
circumstances surrounding an authentication attempt, such as, for
example, the time of day, IP address or subnet mask, purchasing
profile, email address, processor serial number or ID, or the
like.
[0084] Moreover, the nature of biometric data comparisons may
result in varying degrees of confidence being produced from the
matching of current biometric authentication data to enrollment
data. For example, unlike a traditional password which may only
return a positive or negative match, a fingerprint may be
determined to be a partial match, e.g. a 90% match, a 75% match, or
a 10% match, rather than simply being correct or incorrect. Other
biometric identifiers such as voice print analysis or face
recognition may share this property of probabilistic
authentication, rather than absolute authentication.
[0085] When working with such probabilistic authentication or in
other cases where an authentication is considered less than
absolutely reliable, it is desirable to apply the heuristics 530 to
determine whether the level of confidence in the authentication
provided is sufficiently high to authenticate the transaction which
is being made.
[0086] It will sometimes be the case that the transaction at issue
is a relatively low value transaction where it is acceptable to be
authenticated to a lower level of confidence. This could include a
transaction which has a low dollar value associated with it (e.g.,
a $10 purchase) or a transaction with low risk (e.g., admission to
a members-only web site).
[0087] Conversely, for authenticating other transactions, it may be
desirable to require a high degree of confidence in the
authentication before allowing the transaction to proceed. Such
transactions may include transactions of large dollar value (e.g.,
signing a multi-million dollar supply contract) or transaction with
a high risk if an improper authentication occurs (e.g., remotely
logging onto a government computer).
[0088] The use of the heuristics 530 in combination with confidence
levels and transactions values may be used as will be described
below to allow the comparator to provide a dynamic
context-sensitive authentication system.
[0089] According to another embodiment of the invention, the
comparator 515 may advantageously track authentication attempts for
a particular transaction. For example, when a transaction fails,
the trust engine 110 may request the user to re-enter his or her
current authentication data. The comparator 515 of the
authentication engine 215 may advantageously employ an attempt
limiter 535 to limit the number of authentication attempts, thereby
prohibiting brute-force attempts to impersonate a user's
authentication data. According to one embodiment, the attempt
limiter 535 comprises a software module monitoring transactions for
repeating authentication attempts and, for example, limiting the
authentication attempts for a given transaction to three. Thus, the
attempt limiter 535 will limit an automated attempt to impersonate
an individual's authentication data to, for example, simply three
"guesses." Upon three failures, the attempt limiter 535 may
advantageously deny additional authentication attempts. Such denial
may advantageously be implemented through, for example, the
comparator 515 returning a negative result regardless of the
current authentication data being transmitted. On the other hand,
the transaction engine 205 may advantageously block any additional
authentication attempts pertaining to a transaction in which three
attempts have previously failed.
[0090] The authentication engine 215 also includes the data
splitting module 520 and the data assembling module 525. The data
splitting module 520 advantageously comprises a software, hardware,
or combination module having the ability to mathematically operate
on various data so as to substantially randomize (e.g., randomize
or pseudo-randomize) and split the data into individual portions
(also called shares). In some embodiments, to substantially
randomize data, data splitting module 520 may generate random or
pseudo-random numbers. The random or pseudo-random numbers may then
be associated with units (e.g., any number of bits, bytes, or
blocks) of data from a data set. The random or pseudo-random
numbers may also be associated with the shares. Data splitting
module 520 may determine into which share to store each unit of
data from the data set based on, at least in part, the association
of the random or pseudo-random numbers with the units of data and
the shares.
[0091] According to one embodiment, original data is not
recreatable from an individual portion or user share. The data
assembling module 525 advantageously comprises a software,
hardware, or combination module configured to mathematically
operate on the foregoing substantially randomized portions, such
that the combination thereof provides the original deciphered data.
According to one embodiment, the authentication engine 215 employs
the data splitting module 520 to randomize and split enrollment
authentication data into portions, and employs the data assembling
module 525 to reassemble the portions into usable enrollment
authentication data.
[0092] FIG. 6 illustrates a block diagram of the cryptographic
engine 220 of the trust engine 200 of FIG. 2 according to aspects
of one embodiment of the invention. Similar to the transaction
engine 205 of FIG. 3, the cryptographic engine 220 comprises an
operating system 605 having at least a listening and a handling
thread of a modified version of a conventional Web server, such as,
for example, Web servers available from Apache. As shown in FIG. 6,
the cryptographic engine 220 comprises a data splitting module 610
and a data assembling module 620 that function similar to those of
FIG. 5. However, according to one embodiment, the data splitting
module 610 and the data assembling module 620 process cryptographic
key data, as opposed to the foregoing enrollment authentication
data. Although, a skilled artisan will recognize from the
disclosure herein that the data splitting module 910 and the data
splitting module 620 may be combined with those of the
authentication engine 215.
[0093] The cryptographic engine 220 also comprises a cryptographic
handling module 625 configured to perform one, some or all of a
wide number of cryptographic functions. According to one
embodiment, the cryptographic handling module 625 may comprise
software modules or programs, hardware, or both. According to
another embodiment, the cryptographic handling module 625 may
perform data comparisons, data parsing, data splitting, data
separating, data hashing, data encryption or decryption, digital
signature verification or creation, digital certificate generation,
storage, or requests, cryptographic key generation, or the like.
Moreover, a skilled artisan will recognize from the disclosure
herein that the cryptographic handling module 825 may
advantageously comprises a public-key infrastructure, such as
Pretty Good Privacy (PGP), an RSA-based public-key system, or a
wide number of alternative key management systems. In addition, the
cryptographic handling module 625 may perform public-key
encryption, symmetric-key encryption, or both. In addition to the
foregoing, the cryptographic handling module 625 may include one or
more computer programs or modules, hardware, or both, for
implementing seamless, transparent, interoperability functions.
[0094] A skilled artisan will also recognize from the disclosure
herein that the cryptographic functionality may include a wide
number or variety of functions generally relating to cryptographic
key management systems.
[0095] The secure data parser of the present invention may be
integrated into an operating system kernel (e.g., Linux, Unix, or
any other suitable commercial or proprietary operating system).
This integration may be used to protect data at the device level
whereby, for example, data that would ordinarily be stored in one
or more devices is separated into a certain number of portions by
the secure data parser integrated into the operating system and
stored among the one or more devices. When original data is
attempted to be accessed, the appropriate software, also integrated
into the operating system, may recombine the parsed data portions
into the original data in a way that may be transparent to the end
user.
[0096] The secure data parser of the present invention may be
integrated into a volume manager or any other suitable component of
a storage system to protect local and networked data storage across
any or all supported platforms. For example, with the secure data
parser integrated, a storage system may make use of the redundancy
offered by the secure data parser (i.e., which is used to implement
the feature of needing fewer than all separated portions of data in
order to reconstruct the original data) to protect against data
loss. The secure data parser also allows all data written to
storage devices, whether using redundancy or not, to be in the form
of multiple portions that are generated according to the parsing of
the present invention. When original data is attempted to be
accessed, the appropriate software, also integrated into the volume
manager or other suitable component of the storage system, may
recombine the parsed data portions into the original data in a way
that may be transparent to the end user.
[0097] In one suitable approach, the secure data parser of the
present invention may be integrated into a RAID controller (as
either hardware or software). This allows for the secure storage of
data to multiple drives while maintaining fault tolerance in case
of drive failure.
[0098] The secure data parser of the present invention may be
integrated into a database in order to, for example, protect
sensitive table information. For example, in one suitable approach,
data associated with particular cells of a database table (e.g.,
individual cells, one or more particular columns, one or more
particular rows, any combination thereof, or an entire database
table) may be parsed and separated according to the present
invention (e.g., where the different portions are stored on one or
more storage devices at one or more locations or on a single
storage device). Access to recombine the portions in order to view
the original data may be granted by traditional authentication
methods (e.g., username and password query).
[0099] The secure parser of the present invention may be integrated
in any suitable system that involves data in motion (i.e., transfer
of data from one location to another). Such systems include, for
example, network file servers and file systems, email servers, web
servers, streaming data broadcasts, and wireless (e.g., WiFi)
communications. With respect to email, in one suitable approach,
the secure parser may be used to parse outgoing messages (i.e.,
containing text, binary data, or both (e.g., files attached to an
email message)) and sending the different portions of the parsed
data along different paths thus creating multiple streams of data.
If any one of these streams of data is compromised, the original
message remains secure because the system may require that more
than one of the portions be combined, in accordance with the
present invention, in order to generate the original data. In
another suitable approach, the different portions of data may be
communicated along one path sequentially so that if one portion is
obtained, it may not be sufficient to generate the original data.
The different portions arrive at the intended recipient's location
and may be combined to generate the original data in accordance
with the present invention.
[0100] FIGS. 7 and 8 are illustrative block diagrams of such email
systems. FIG. 7 shows a sender system 700, which may include any
suitable hardware, such as a computer terminal, personal computer,
handheld device (e.g., PDA, Blackberry), cellular telephone,
computer network, any other suitable hardware, or any combination
thereof. Sender system 700 is used to generate and/or store a
message 704, which may be, for example, a network packet, an email
message, a binary data file (e.g., graphics, voice, video, etc.),
or any combination of the foregoing. Message 704 is parsed and
split by secure data parser 702 in accordance with the present
invention. The resultant data portions may be communicated across
one or more separate communications paths 706 over network 708
(e.g., the Internet, an intranet, a LAN, WiFi, Bluetooth, any other
suitable hard-wired or wireless communications means, or any
combination thereof) to recipient system 710. The data portions may
be communicated parallel in time or alternatively, according to any
suitable time delay between the communication of the different data
portions. Recipient system 710 may be any suitable hardware as
described above with respect to sender system 700. The separate
data portions carried along communications paths 706 are recombined
at recipient system 710 to generate the original message or data in
accordance with the present invention.
[0101] FIG. 8 shows a sender system 800, which may include any
suitable hardware, such as a computer terminal, personal computer,
handheld device (e.g., PDA), cellular telephone, computer network,
any other suitable hardware, or any combination thereof. Sender
system 800 is used to generate and/or store a message 804, which
may be, for example, a network packet, an email message, a binary
data file (e.g., graphics, voice, video, etc.), or any combination
of the foregoing. Message 804 is parsed and split by secure data
parser 802 in accordance with the present invention. The resultant
data portions may be communicated across a single communications
paths 806 over network 808 (e.g., the Internet, an intranet, a LAN,
WiFi, Bluetooth, any other suitable communications means, or any
combination thereof) to recipient system 810. The data portions may
be communicated serially across communications path 806 with
respect to one another. Recipient system 810 may be any suitable
hardware as described above with respect to sender system 800. The
separate data portions carried along communications path 806 are
recombined at recipient system 810 to generate the original message
or data in accordance with the present invention.
[0102] It will be understood that the arrangement of FIGS. 7 and 8
are merely illustrative. Any other suitable arrangement may be
used. For example, in another suitable approach, the features of
the systems of FIGS. 7 and 8 may be combined whereby the multi-path
approach of FIG. 7 is used and in which one or more of
communications paths 706 are used to carry more than one portion of
data as communications path 806 does in the context of FIG. 8.
[0103] The secure data parser may be integrated at any suitable
level of a data-in motion system. For example, in the context of an
email system, the secure parser may be integrated at the
user-interface level (e.g., into Microsoft.RTM. Outlook), in which
case the user may have control over the use of the secure data
parser features when using email. Alternatively, the secure parser
may be implemented in a back-end component such as at the exchange
server, in which case messages may be automatically parsed, split,
and communicated along different paths in accordance with the
present invention without any user intervention. In some
embodiments, the integration may be transparent to the user.
[0104] Similarly, in the case of streaming broadcasts of data
(e.g., audio, video), the outgoing data may be parsed and separated
into multiple streams each containing a portion of the parsed data.
The multiple streams may be transmitted along one or more paths and
recombined at the recipient's location in accordance with the
present invention. One of the benefits of this approach is that it
avoids the relatively large overhead associated with traditional
encryption of data followed by transmission of the encrypted data
over a single communications channel. The secure parser of the
present invention allows data in motion to be sent in multiple
parallel streams, increasing speed and efficiency.
[0105] It will be understand that the secure data parser may be
integrated for protection of and fault tolerance of any type of
data in motion through any transport medium, including, for
example, wired, wireless, or physical. For example, voice over
Internet protocol (VoIP) applications may make use of the secure
data parser of the present invention. Wireless or wired data
transport from or to any suitable personal digital assistant (PDA)
devices such as Blackberries and SmartPhones may be secured using
the secure data parser of the present invention. Communications
using wireless 802.11 protocols for peer to peer and hub based
wireless networks, satellite communications, point to point
wireless communications, Internet client/server communications, or
any other suitable communications may involve the data in motion
capabilities of the secure data parser in accordance with the
present invention. Data communication between computer peripheral
device (e.g., printer, scanner, monitor, keyboard, network router,
biometric authentication device (e.g., fingerprint scanner), or any
other suitable peripheral device) between a computer and a computer
peripheral device, between a computer peripheral device and any
other suitable device, or any combination thereof may make use of
the data in motion features of the present invention.
[0106] The data in motion features of the present invention may
also apply to physical transportation of secure shares using for
example, separate routes, vehicles, methods, any other suitable
physical transportation, or any combination thereof. For example,
physical transportation of data may take place on digital/magnetic
tapes, floppy disks, optical disks, physical tokens, USB drives,
removable hard drives, consumer electronic devices with flash
memory (e.g., Apple IPODs or other MP3 players), flash memory, any
other suitable medium used for transporting data, or any
combination thereof.
[0107] The secure data parser of the present invention may provide
security with the ability for disaster recovery. According to the
present invention, fewer than all portions of the separated data
generated by the secure data parser may be necessary in order to
retrieve the original data. That is, out of m portions stored, n
may be the minimum number of these m portions necessary to retrieve
the original data, where n<=m. For example, if each of four
portions is stored in a different physical location relative to the
other three portions, then, if n=2 in this example, two of the
locations may be compromised whereby data is destroyed or
inaccessible, and the original data may still be retrieved from the
portions in the other two locations. Any suitable value for n or m
may be used.
[0108] In addition, the n of m feature of the present invention may
be used to create a "two man rule" whereby in order to avoid
entrusting a single individual or any other entity with full access
to what may be sensitive data, two or more distinct entities, each
with a portion of the separated data parsed by the secure parser of
the present invention may need to agree to put their portions
together in order to retrieve the original data.
[0109] The secure data parser of the present invention may be used
to provide a group of entities with a group-wide key that allows
the group members to access particular information authorized to be
accessed by that particular group. The group key may be one of the
data portions generated by the secure parser in accordance with the
present invention that may be required to be combined with another
portion centrally stored, for example in order to retrieve the
information sought. This feature allows for, for example, secure
collaboration among a group. It may be applied in for example,
dedicated networks, virtual private networks, intranets, or any
other suitable network.
[0110] Specific applications of this use of the secure parser
include, for example, coalition information sharing in which, for
example, multi-national friendly government forces are given the
capability to communicate operational and otherwise sensitive data
on a security level authorized to each respective country over a
single network or a dual network (i.e., as compared to the many
networks involving relatively substantial manual processes
currently used). This capability is also applicable for companies
or other organizations in which information needed to be known by
one or more specific individuals (within the organization or
without) may be communicated over a single network without the need
to worry about unauthorized individuals viewing the
information.
[0111] Another specific application includes a multi-level security
hierarchy for government systems. That is, the secure parser of the
present invention may provide for the ability to operate a
government system at different levels of classified information
(e.g., unclassified, classified, secret, top secret) using a single
network. If desired, more networks may be used (e.g., a separate
network for top secret), but the present invention allows for
substantially fewer than current arrangement in which a separate
network is used for each level of classification.
[0112] It will be understood that any combination of the above
described applications of the secure parser of the present
invention may be used. For example, the group key application can
be used together with the data in motion security application
(i.e., whereby data that is communicated over a network can only be
accessed by a member of the respective group and where, while the
data is in motion, it is split among multiple paths (or sent in
sequential portions) in accordance with the present invention).
[0113] The secure data parser of the present invention may be
integrated into any middleware application to enable applications
to securely store data to different database products or to
different devices without modification to either the applications
or the database. Middleware is a general term for any product that
allows two separate and already existing programs to communicate.
For example, in one suitable approach, middleware having the secure
data parser integrated, may be used to allow programs written for a
particular database to communicate with other databases without
custom coding.
[0114] The secure data parser of the present invention may be
implemented having any combination of any suitable capabilities,
such as those discussed herein. In some embodiments of the present
invention, for example, the secure data parser may be implemented
having only certain capabilities whereas other capabilities may be
obtained through the use of external software, hardware, or both
interfaced either directly or indirectly with the secure data
parser.
[0115] The secure data parser of the present invention may be
advantageously used in a number of applications and technologies.
For example, email system, RAID systems, video broadcasting
systems, database systems, tape backup systems, or any other
suitable system may have the secure data parser integrated at any
suitable level. As previously discussed, it will be understand that
the secure data parser may also be integrated for protection and
fault tolerance of any type of data in motion through any transport
medium, including, for example, wired, wireless, or physical
transport mediums. As one example, voice over Internet protocol
(VoIP) applications may make use of the secure data parser of the
present invention to solve problems relating to echoes and delays
that are commonly found in VoIP. The need for network retry on
dropped packets may be eliminated by using fault tolerance, which
guarantees packet delivery even with the loss of a predetermined
number of shares. Packets of data (e.g., network packets) may also
be efficiently split and restored "on-the-fly" with minimal delay
and buffering, resulting in a comprehensive solution for various
types of data in motion. The secure data parser may act on network
data packets, network voice packets, file system data blocks, or
any other suitable unit of information. In addition to being
integrated with a VoIP application, the secure data parser may be
integrated with a file-sharing application (e.g., a peer-to-peer
file-sharing application), a video broadcasting application, an
electronic voting or polling application (which may implement an
electronic voting protocol and blind signatures, such as the Sensus
protocol), an email application, or any other network application
that may require or desire secure communication.
[0116] In some embodiments, support for network data in motion may
be provided by the secure data parser of the present invention in
two distinct phases--a header generation phase and a data
partitioning phase. Simplified header generation process 900 and
simplified data partitioning process 910 are shown in FIGS. 9A and
9B, respectively. One or both of these processes may be performed
on network packets, file system blocks, or any other suitable
information.
[0117] In some embodiments, header generation process 900 shown in
FIG. 9A may be performed one time at the initiation of a network
packet stream. At step 902, a random (or pseudo-random) split
encryption key, K, may be generated. The split encryption key, K,
may then be optionally encrypted (e.g., using the workgroup key
described above) at AES key wrap step 904. Although an AES key wrap
may be used in some embodiments, any suitable key encryption or key
wrap algorithm may be used in other embodiments. AES key wrap step
904 may operate on the entire split encryption key, K, or the split
encryption key may be parsed into several blocks (e.g., 64-bit
blocks). AES key wrap step 904 may then operate on blocks of the
split encryption key, if desired.
[0118] At step 906, a secret sharing algorithm (e.g., Shamir) may
be used to split the split encryption key, K, into key shares. Each
key share may then be embedded into one of the output shares (e.g.,
in the share headers). Finally, a share integrity block and
(optionally) a post-authentication tag (e.g., MAC) may be appended
to the header block of each share. Each header block may be
designed to fit within a single data packet.
[0119] After header generation is complete (e.g., using simplified
header generation process 900), the secure data parser may enter
the data partitioning phase shown in FIG. 9B using simplified data
splitting process 910. Each incoming data packet or data block in
the stream is encrypted using the split encryption key, K, at step
912. At step 914, share integrity information (e.g., a hash H) may
be computed on the resulting ciphertext from step 912. For example,
a SHA-256 hash may be computed. At step 916, the data packet or
data block may then be partitioned into two or more data shares
using one of the data splitting algorithms described above in
accordance with the present invention. In some embodiments, the
data packet or data block may be split so that each data share
contains a substantially random distribution of the encrypted data
packet or data block. The integrity information (e.g., hash H) may
then be appended to each data share. An optional
post-authentication tag (e.g., MAC) may also be computed and
appended to each data share in some embodiments.
[0120] Each data share may include metadata, which may be necessary
to permit correct reconstruction of the data blocks or data
packets. This information may be included in the share header. The
metadata may include such information as cryptographic key shares,
key identities or identifiers, share nonces, signatures/MAC values,
and integrity blocks. In order to maximize bandwidth efficiency,
the metadata may be stored in a compact binary format.
[0121] For example, in some embodiments, the share header may
include a cleartext header chunk, which is not encrypted and may
include such elements as the Shamir key share, per-session nonce,
per-share nonce, and key identifiers (e.g., a workgroup key
identifier and a post-authentication key identifier). The share
header may also include an encrypted header chunk, which is
encrypted using the split encryption key. An integrity header
chunk, which may include integrity checks for any number of the
previous blocks (e.g., the previous two blocks) may also be
included in the header. Any other suitable values or information
may also be included in the share header in other embodiments.
[0122] As shown in illustrative share format 1000 of FIG. 10,
header block 1002 may be associated with two or more output blocks
1004. Each header block, such as header block 1002, may be designed
to fit within a single network data packet. In some embodiments,
after header block 1002 is transmitted from a first location to a
second location, the output blocks may then be transmitted.
Alternatively, header block 1002 and output blocks 1004 may be
transmitted at the same time in parallel. The transmission may
occur over one or more similar or dissimilar communications
paths.
[0123] Each output block may include data portion 1006 and
integrity/authenticity portion 1008. As described above, each data
share may be secured using a share integrity portion including
share integrity information (e.g., a SHA-256 hash) of the
encrypted, pre-partitioned data. To verify the integrity of the
outputs blocks at recovery time, the secure data parser may compare
the share integrity blocks of each share and then invert the split
algorithm. The hash of the recovered data may then be verified
against the share hash.
[0124] As described above, the secure data parser of the present
invention may also be used to secure data in motion (or data being
communicated from one system or service to another) within a
workgroup. In some embodiments, a centralized server handles all
user, service, and workgroup management for a single domain (or
across multiple domains). The centralized server may include one
server or a cluster of servers (for fault-tolerance) and may
include an LDAP server, such as a server running Microsoft.RTM.
Server 2003 and Active Directory.
[0125] Seamless user authentication within a workgroup may be
provided using challenge/response protocol 1100 as shown in FIG.
11. Using protocol 1100, workgroup client 1102 may authenticate
itself to authentication server 1104. Seamless user authentication
may be granted through the verification of a shared secret (for
example, using Digest Authentication). When a user logs onto
workgroup client 1102, a password entered by the user may be put
through a cryptographic function transforming the ASCII text of the
password into a cryptographic key. This password-based key (labeled
"PBK" in the example of FIG. 11) may also be stored on, or
accessible by, authentication server 1104.
[0126] To be authenticated, workgroup client 1102 may identify
itself to authentication server 1104 with message 1106. For
example, message 1106 may include data indicative of the user's
identity, such as, for example, the user's workgroup name, logon
username, network address, MAC address, or any combination of the
foregoing. In response to message 1106, authentication server 1104
may send workgroup client 1102 a challenge value in message 1108.
The challenge value may include any number of bits or bytes which,
after received by workgroup client 1102, may be encrypted using the
password-based key. The resulting ciphertext (labeled "Y" in the
example of FIG. 11) may then be returned to the server in message
1110. Authentication server 1104 may then perform the same
encryption on the challenge value using the stored password-based
key for the workgroup client and verify that its own encryption and
the received ciphertext match. If there is a match, the user has
been authenticated. Otherwise, the authentication request may be
denied.
[0127] FIG. 12 shows illustrative process 1200 for communicating
with a service on the network. Process 1200 may be implemented
using a Kerberos subsystem, which allows two workgroup clients
(such as clients 1202 and 1206) on a network to prove their
authenticity to one another through the use of a central server
sometimes referred to as Key Distribution Center (KDC) 1204.
[0128] After being authenticated (e.g., using a challenge/response
protocol as shown by messages 1208), a user may be given a Ticket
Granting Ticket (TGT) in message 1210. This ticket may serve as a
token to be given to KDC 1204 whenever client 1202 intends to
communicate with another user or service on the network (such as a
web server, email server, or client 1206). The TGT may include, for
example, a block of information containing the name or identity of
the recipient, a timestamp, and any other necessary credentials.
The TGT may also be encrypted under the KDC's Master Key so that
only the KDC can read its contents.
[0129] When a user with a TGT wants to communicate with a service
on the network, it may pass the TGT to the KDC and request a valid
Service Ticket (ST). For example, as shown in FIG. 12, workgroup
client 1202 has requested a ST for client 1206 via message 1212. If
the TGT is valid, KDC 1204 may return to client 1202 two STs via
message 1214, each ST containing the credentials of the parties
involved in the communication, a timestamp, and a unique and fresh
session key (SK) to be used as a temporary shared key between both
parties for encryption. One of the STs may be encrypted under the
shared password-based key between the user and the KDC, and the
other ST may be encrypted under the shared password-based key
between the service or client being contacted (e.g., client 1206)
and the KDC.
[0130] The ST encrypted for client 1202 making the request can
immediately be decrypted by client 1202 and the SK uncovered.
Client 1202 may then send the second ST and a message encrypted
under the SK to the targeted service or client (e.g., client 1206)
via message 1216. In a final step, the service or client (e.g.,
client 1206) may then decrypt the ST with its password-based key to
obtain the SK, and subsequently decrypt the message sent by client
1202. Through this process, clients 1202 and 1206 now share the
SK.
[0131] In practice, one or more steps shown in process 1200 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0132] FIG. 13 shows illustrative process 1300 for using shared
keys with the secure data parser. The SK described above may be
used as a shared workgroup key (WK) to support secure workgroup
communication using the secure data parser. In some embodiments,
the secure data parser WK may be used to wrap internally generated
session keys, including the Encryption Session Key (ESK) and the
MAC session key (MK), as described in more detail in U.S. Pat. No.
7,391,865 and U.S. patent application Ser. No. 10/458,928, filed
Jun. 11, 2003, Ser. No. 11/258,839, filed Oct. 25, 2005, Ser. No.
11/602,667, filed Nov. 20, 2006, Ser. No. 11/983,355, filed Nov. 7,
2007, Ser. No. 11/999,575, filed Dec. 5, 2007, Ser. No. 12/209,703,
filed Sep. 12, 2008, and Ser. No. 12/349,897, filed Jan. 7,
2009.
[0133] After wrapped with the WK, the ciphertexts may be securely
shared (e.g., using a secret sharing scheme, such as Shamir) among
each header generated by the secure data parser, where a single
share of each wrapped key is stored with each header. Obtaining the
ESK or MK may now require obtaining WK and a quorum of shares
sufficient to rebuild the wrapped ESK and MK ciphertexts. In some
embodiments, the secure data parser WK may be used to wrap an
internally generated Encryption Session Key (ESK). Once wrapped
with the WK, the ciphertext may be again wrapped with a freshly
generated Key Encrypting Key (KEK). Now the ESK has been doubly
wrapped and may only be recovered with knowledge of both the WK and
the KEK. The KEK may be securely shared among each header generated
by the secure data parser, and the doubly wrapped ESK may be stored
within each header. Obtaining the ESK now may require obtaining the
WK and a quorum of shares sufficient to rebuild the KEK. In a
typical communication session, two users or workgroup clients may
obtain tickets encrypted only for each client individually, the
tickets containing the WK value. The WK value may then be imported
in to the KeyStore for each of the two users or clients and used as
a normal WK in the context of a secure data parser communication
session.
[0134] For example, client 1302 may import a shared WK into its
KeyStore and generate secure data parser headers, as described
above in regard to FIGS. 9 and 10. The secure data parser headers
may include one or more of the WK, the workgroup-key ID, and the WK
version number (e.g., the WK, key ID, and version number may be
shared out to the headers using a secret sharing scheme, such as
Shamir, in some embodiments). Client 1302 may then send these
headers to client 1304 via messages 1306. Client 1304 may
reconstruct the WK, the workgroup-key ID, and the WK version number
from received headers and import the WK into its KeyStore. After
each client has stored the WK in its respective KeyStore, a secure
data parser communications session (e.g., parsing a data set and
restoring the data set) may then take place using data messages
1308 and 1310.
[0135] In practice, one or more steps shown in process 1300 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0136] In order for the above mechanisms to be integrated with a
kernel-level network driver, in some embodiments, authentication
server modifications are provided to distribute the session keys.
Workstation modifications may also be provided, in some
embodiments, to request TGTs and STs. Process 1400, as shown in
FIG. 14, illustrates an exemplary message sequence. For example,
Kerberos functionality and communication with KDC 1406 generally
cannot occur in kernel space 1404. Instead, the network driver may
call back to user space 1402 to perform the Kerberos key exchanges,
then pass back down any data that is used by the network driver (or
sent to the original destination). For example, after client 1401
wishes to communicate with client 1419, message 1408 may be
generated and delivered from user space 1402 to the network driver
in kernel space 1404. The network driver may determine whether or
not there is already a secure date parser session with the desired
destination IP address (or other network identifier), and, if so,
may use that channel. If there is no existing session, the network
driver may pass the IP address (or other network identifier) up to
a user-level service to obtain STs using message 1410.
[0137] The service may then determine whether or not the STs for
the given IP address (or other network identifier) are currently
cached, and, if not, the user-level service may obtain the STs from
KDC 1406 via messages 1412. Next, the user-level service may
decrypt the embedded WK in the ST for client 1401 and pass the WK
and the ST for client 1419 back to the network driver in kernel
space 1404 via message 1414. The network driver may then use the WK
to generate secure data parser headers and send them, along with
the ST for client 1419, to client 1419 via messages 1416. After
receiving the headers and the ST at the network driver of client
1419, the ST may then be passed up to its own user-level service
via message 1418. The user-level service may decrypt the ST and
extract the WK, which is then passed back down to the network
driver via message 1420. Client 1419 may then use WK to restore the
secure data parser headers it has received and complete the
channel.
[0138] In practice, one or more steps shown in process 1400 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0139] FIG. 15 shows illustrative network topology 1500.
Certificate Authority (CA) 1502 may enroll each Workgroup Authority
(WA) in the network or domain. Although in the example of FIG. 15
three WAs are shown (i.e., WA 1504, WA 1506, and WA 1508), in
actual implementations there may be more or less than three WAs in
a single network or domain. CA 1502 may enroll each of WA 1504, WA
1506, and WA 1508 by issuing each WA a WA certificate for their
respective workgroup. The certificates may be digitally signed by
CA 1502 to prevent tampering.
[0140] After being enrolled by CA 1602, WA 1504, WA 1506, and WA
1508 may begin enrolling clients (e.g., users, machines, and
services) into their respective workgroups. For example, in some
embodiments, enrollment may be based, at least in part, on
pre-exiting Active Directory (or other LDAP) membership semantics.
Enrolled clients may be issued certificates signed by their
respective WA, as well as the certificates of the WA, CA, or
both.
[0141] FIG. 16 shows illustrative connection setup 1600. Initiator
1604 may first ensure that it is using the latest WK by performing
key update 1608 with WA 1602. Initiator 1604 may provide a nonce to
WA 1602 and prove that it possesses a valid certificate. WA 1602
may then provide an encrypted and signed WK that includes the
initiator's nonce. In some embodiments, encryption is performed
using RSA PKCS #1 v2 with RSA-PSS or ECDSA signatures. In other
embodiments, AES-GCM authenticated encryption is used under
pre-shared symmetric keys.
[0142] Initiator 1604 then initiates a connection with recipient
1606 using the latest WK with request message 1610. After receiving
the connection request, recipient 1606 may ensure that it has the
latest WK. Key update 1612 may be performed in the same encrypted,
authenticated replay-resistant manner as performed by initiator
1604. If recipient 1606 belongs to more then one workgroup,
recipient 1606 selects the appropriate WA based, at least in part,
on the workgroup-key ID supplied in request message 1610. If
initiator 1604 and recipient 1606 retrieve the same WK from WA
1602, then recipient 1606 may send successful connection message
1614 to initiator 1604.
[0143] One or both of the key update steps shown in connection
setup 1600 may be performed upon initial connection with another
workgroup client, periodically after a workgroup key refresh alarm
time has been reached, or periodically on any other suitable
schedule. In some embodiments, as described in more detail below,
key updates are performed automatically before every new
communication session is established. System or user control of the
workgroup key TTL and refresh alarm may provide customized levels
of renewability. This may be beneficial, for example, after a
client's communication privileges have been revoked and immediate
revocability is desired.
[0144] The need for certificate revocation lists (CRLs) may also be
reduced or even altogether eliminated using this approach.
Workgroup membership may be maintained by the authentication or
LDAP server. In some embodiments, WA revocation is also supported
using the Online Certificate Status Protocol (OCSP). For example,
an OSCP responder may determine the status of a WA's certificate
without checking CRL published by the CA.
[0145] In practice, one or more steps shown in connection setup
1700 may be combined with other steps, performed in any suitable
order, performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0146] FIGS. 17-20 show illustrative processes for supporting the
secure workgroup key management and distribution of the present
invention. FIG. 17 shows illustrative process 1700 for joining a
new workgroup. At step 1702, client n may indicate a desire to join
a workgroup. At step 1704, the WA may generate a secret key E.sub.n
for the client. In some embodiments, E.sub.n may be a key for a
symmetric cipher. In other embodiments, a public-key encryption
scheme using an asymmetric cipher may be used and E.sub.n may be a
key (e.g., a private key) for an asymmetric cipher. For example,
the Naor, Naor and Lotspeich subset cover broadcast encryption
approach may be used in place of the symmetric scheme described
below. This public-key encryption algorithm may be built on top of
any other secure public-key encryption scheme.
[0147] Key generation using the public-key approach, in some
embodiments, may be performed centrally by the WA. If M is the
maximum workgroup size, then the WA may generate 2M-1 distinct
public/private keypairs. If a binary tree exists of span M, with
each keypair associated with an internal node in the tree, then for
each device or client in the workgroup, the i.sup.th leaf in the
tree could be chosen and the device or client i could be provided
with each keypair associated with the i.sup.th leaf upward to the
root of the tree. The total size of the device or client's key
material may then be equal to log M+1. Other approaches for key
generation using a public-key or secret key approach may be used in
other embodiments.
[0148] At step 1706, the WA may store one or more of the identity
of the client n, the client's secret key E.sub.n, and a list of
authorized workgroup-key IDs. At step 1708, client n may store its
secret key E.sub.n. For example, the client may store its secret
key locally in a key store. At step 1710, client n may also store
the workgroup-key ID (e.g., public knowledge and/or string
identifier) and set the workgroup key refresh alarm to 0 (i.e.,
immediate) and key version to 0.
[0149] A single client may belong to one or more workgroups. Each
workgroup (and hence current WK for that workgroup) may be
associated with a unique workgroup identifier. The unique workgroup
identifiers and associated workgroup-key IDs may help the client
and WA determine to which workgroup or workgroups the client
currently belongs as well as determine which workgroup key to use
to establish a communication session with another client who also
belongs to one or more workgroups.
[0150] In practice, one or more steps shown in process 1700 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0151] FIGS. 18A, 18B, and 18C show illustrative process 1800 for
initiating a connection between two clients. At step 1802, client 1
may initiate a communication session with client 2. For example,
client 1 may send its identity (e.g., network address or username)
to client 2 and request a communication session with client 2. At
step 1804, client 1 may check its workgroup key refresh alarm time.
At step 1804, client 1 may also verify that any time to live (TTL)
value associated with client 1's WK has not expired. For example,
in order to determine if client 1's WK is expired, client 1 may
compare the TTL value associated with client 1's WK to the current
time or the WK timestamp. The WK timestamp may indicate when the WK
was generated or delivered to client 1. If, at step 1806, the
refresh alarm time is greater than the current time (or WK
timestamp), illustrative process 1800 may continue in FIG. 18B. If,
at step 1806, the refresh alarm time is not greater than the
current time (or WK timestamp), at step 1808, client 1 may contact
client 2 with the secure data parser's generated headers. These
headers may include, for example, the WK and WK version number. At
step 1810, client 2 may read the workgroup-key ID. If, at step
1812, the workgroup-key ID is not valid for this workgroup (or a
workgroup to which client 2 currently belongs), client 2 may report
the error to the calling application at step 1814. In some
embodiments, the calling application may determine the response to
the signaled error. If, at step 1812, the workgroup-key ID is valid
for this workgroup (or a workgroup to which client 2 currently
belongs), illustrative process 1800 may continue in FIG. 18C.
[0152] FIG. 18B continues illustrative process 1800 after it is
determined, at step 1806, that the refresh alarm time is greater
than the current time (or WK timestamp). In some embodiments, this
may indicate a stale WK. In order for client 1 to continue, in some
embodiments, it must contact the WA and refresh its WK. At step
1816, client 1 may generate a nonce N.sub.1. At step 1816, client 1
may also send a message to the WA. In some embodiments, the message
may be formatted as follows: {Client 1.parallel.E.sub.1
{UP-TO-DATE?.parallel.N.sub.1.parallel.workgroup-key
ID.parallel.client workgroup key version}}, where Client 1 is the
identity of client 1, E.sub.1 is a cryptographic function based, at
least in part, on client 1's secret key, and UP-TO-DATE? is the
message type.
[0153] At step 1818, the WA may look up client 1 and access
E.sub.1, client 1's secret key. As previous described, the WA may
store each workgroup member's secret key in a key store, key
repository, or database. At step 1818, the WA may also decrypt the
message sent by client 1 at step 1816. At step 1820, the WA may
determine if client 1 is authorized by validating that the received
workgroup-key ID is authorized for this client. The WA may also
check to see if there is a newer version of the WK and calculate
how long until the WK expires (e.g., a "time to live" or TTL value
for the WK may be computed). If, at step 1820, the WA determines
that the client is not found or not authorized for this workgroup,
the WA may send back a not authorized message at step 1822.
Otherwise, at step 1824, the WA may send back a message encrypted
with client 1's secret key. The message may be in the following
format in some embodiments: E.sub.1
{UP-TO-DATE?.parallel.N.sub.1.parallel.workgroup-key
ID.parallel.current workgroup key version.parallel.TTL}.
[0154] At step 1826, client 1 may decrypt the message and compare
is WK version with the current WK version. If client 1's WK version
is earlier that the current WK version, client 1 may update its WK
at step 1830. An illustrative process a client may use to update
its WK is described with regard to FIG. 20 below. If client 1's WK
version is not earlier than the current WK version (e.g., it is the
current version), then client 1 may update its WK refresh alarm to
the current time plus the TTL calculated by the WA at step
1828.
[0155] Referring now to FIG. 18C, if the workgroup-key ID is valid
for the particular workgroup, client 2 may then determine if the
version number of client 1's WK is less than client 2's current
version number at step 1832. If so, client 2 may report an error to
the calling application at step 1834. In some embodiments, the
calling application may determine the response to the signaled
error (e.g., the calling application may automatically perform a
key update to obtain a newer version of the WK and retry the
connection). If, at step 1832, client 2 determines that client 1's
WK version number is not greater than client 2's version, client 2
may then determine if the current time is greater than the WK
refresh alarm time at step 1836. If the current time is greater
than the refresh alarm time, client 2 may contact the WA using the
UP-TO-DATE? (described above) and/or KEY-REQUEST (described in
regard to FIG. 20 below) message types to verify the freshness of
the current workgroup key, request a new workgroup key, or both. It
should be noted that the UP-TO-DATE? message type may be an
optimization for checking that a workgroup key is fresh.
Nevertheless, the KEY-REQUEST message type can be used without a
preceding UP-TO-DATE? message type in order to reduce latency. In
other embodiments, the WA may force clients to check the freshness
of keys on every connection attempt by setting the TTL to 0.
[0156] After updating its key at step 1838 (or if the current time
was not greater than the refresh alarm time at step 1836), client 2
may then determine, at step 1840, if the version number of client
1's WK is not equal to client 2's now up-to-date version number. If
the two version numbers are not the same, client 2 may report an
error to the calling application at step 1842. If the workgroup-key
ID is valid and the version numbers are identical, client 2 may
report a successful connection attempt to the calling application
at step 1844.
[0157] In practice, one or more steps shown in process 1800 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0158] FIG. 19 shows illustrative process 1900 for revoking the
communication privileges of a workgroup client. As previously
described, traditional secure workgroup communication protocols may
require the use of CRLs and may not support immediate revocability
and renewability of the workgroup security mechanism. The present
invention, however, may support the immediate discovery of revoked
clients by renewing the security mechanism periodically (or at
every connection attempt). For example, to revoke a workgroup
client, the WA may start sending a new WK to all non-revoked users.
By using a versioned WK, connections using a stale WK may be
refused, depending on the security policy in force at the receiving
client.
[0159] A workgroup client revocation request may be received at
step 1902. For example, one or more users may be removed from a
workgroup (or their communication privileges revoked). As
previously described, workgroup membership may be maintained by an
LDAP (e.g., Microsoft.RTM. Active Directory) server in some
embodiments. Certain users (e.g., workgroup administrators) may be
authorized to remove specific users (or groups of users), machines
(e.g., computers and printers), services (e.g., web services and
print/file services), or any combination thereof from a workgroup
using a workgroup administration interface. At step 1904, the
server managing the workgroup membership may determine if the
revocation request is valid. Valid revocation requests may be
authenticated (e.g., singed) by an authorized user or other entity
(e.g., WA or CA) and indicate a valid workgroup user, machine, or
service to revoke. If the revocation request is not valid, an error
may be returned to the calling application at step 1906 and the
revocation request ignored.
[0160] If the revocation request is valid at step 1904, however,
the revoked workgroup-key ID may be removed from the workgroup
client's list at step 1908. For example, the WA may remove the
client's workgroup-key ID from a workgroup-key ID table in a
relational database stored at the WA or CA. At step 1910, the WA
may determine if a key update should be triggered. In some
embodiments, at step 1910, a key update is automatically triggered
in response to each valid revocation request. In other embodiments,
key updates may be triggered only after a predetermined number of
valid revocation requests (as defined by the workgroup security
policy), a predetermined number of currently outstanding revoked
clients, periodically after a predetermined length of time since
the last key update, on-demand by the WA or an authorized user,
automatically after one or more users leave the workgroup, or at
any combination of the foregoing times. Triggering a key update may
implicitly deny access to all revoked users because the revoked
users may not have access to the new WK. Communication using stale
WKs may be controlled, limited, or completely prohibited by
customizing WK version numbers, TTL values computed by the WA, and
WK refresh alarm times.
[0161] If a key update is not triggered at step 1910, illustrative
process 1900 may return to step 1902 to await another revocation
request. If a key update is triggered at step 1910, the WA may
increment its current WK version number and generate a new WK at
step 1912. To generate a new WK, in some embodiments, the WA may
evaluate the workgroup name and current update number using its
Master Key Generation Key (MKGK) through a secure Key Derivation
Function (KDF). Other approaches for generating a new WK may be
used in other embodiments. The newly generated WK may then be
encrypted by the WA and a signed key update message may be
generated at step 1914. In some embodiments, the key update message
generated at step 1914 may include some or all of the following
fields: (1) WA Identifier and Certificate Field, which may include
identifying information for the WA authoring the update, including
its CA-signed certificate; (2) Workgroup Identifier Field, which
may include a unique identifier specifying the name of the
workgroup to which this update applies; (3) Sequence Identifier
Field, which may include a sequential counter indicating the number
of the update; (4) Update Time Period Field, which may include an
indication of the time period during which the key material will be
valid; (5) Update Payload Field, which may include a ciphertext
containing the updated key material; (6) Auxiliary Data Field,
which may include additional information required by the client
(e.g., a key policy and the location where further updates may be
found); (7) Re-keying Flag, which, when set, may instruct the
client to regenerate its secret key and contact the WA for
re-certification; and (8) Signature Filed, which may include a
digital signature computed over the previous fields using the WA's
signing key.
[0162] If a public-key scheme is used, the key update message may
be encrypted to all of the non-revoked users by marking each leaf
in the binary tree described above in regard to FIG. 17 according
to whether the device at that position has been revoked. Then, all
nodes which are parents (or coexistent) to the leaves associated
with non-revoked devices may be identified (but not revoked ones).
For example, the root of the full tree is parent to all of the
leaves; thus, this node is sufficient when no devices are revoked.
Next, the message may be encrypted under each of the keys
associated with those nodes. The result may include a list
identifying these nodes, as well as a list of the ciphertexts
produced. When this encryption scheme is used, each non-revoked
user may possess at least one of the keypairs that was used to
encrypt the message. It may identify this keypair, decrypt the
appropriate ciphertext, and output the message.
[0163] After the key update message has been generated, it may be
published to all non-revoked users via a semi-trusted channel
(e.g., website) at step 1916. Untethered (and semi-tethered)
operation may also be supported. When a client or device is
prepared to go offline, the WA may pre-provision the client or
device with key updates for a limited number of future time
periods. Additionally or alternatively, for devices with some
network access, key revocation and key update messages may be
posted to a highly-available location, e.g., a TLS-secured public
website.
[0164] In practice, one or more steps shown in process 1900 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0165] FIG. 20 shows illustrative process 2000 for requesting a WK
update. At step 2002, a client may send the WA a key request
message encrypted with the client's secret key (or private key, if
an asymmetric encryption scheme is used). For example, at step
2002, the client may send a message in the following format to the
WA: {Client X.parallel.
E.sub.X{KEY-REQUEST.parallel.N.sub.2.parallel.workgroup-key
ID.parallel.requested key version}}, where X is the identity of the
requesting client, E.sub.X is client X's secret key (or private
key, if an asymmetric encryption scheme is used), KEY-REQUEST
represents the key request message type, and N.sub.2 is a nonce
generated by the requesting client. At step 2004, the WA may
receive the encrypted message and look up the client to obtain the
client's secret encryption key E.sub.X. At step 2004, the WA may
also decrypt the key request message and, at step 2006, verify that
the workgroup-key ID is valid for this client. If the workgroup-key
ID is not valid for this client, at step 2008 the WA may send back
a not authorized message and illustrative process 2000 may return
to step 2002. If the workgroup-key ID is valid for this client,
however, the WA may access the newest (i.e., most current) version
of the key (it may be newer than the version requested). The WA may
then create a response to the key request message at step 2012 and
encrypt the response using the client's secret key E.sub.X. In some
embodiments, the WA's response to the key request message may take
the following format:
E.sub.X{KEY-REQUEST.parallel.N.sub.2.parallel.workgroup-key
ID.parallel.current key version.parallel.TTL.parallel.key}. After
receiving the response from the WA, the client may update its WK at
step 2014. Finally, at step 2016, the client may update its WK
refresh alarm time to the current time plus the received TTL
value.
[0166] In practice, one or more steps shown in process 2000 may be
combined with other steps, performed in any suitable order,
performed in parallel (e.g., simultaneously or substantially
simultaneously), or removed.
[0167] A number of key distribution systems and protocols (e.g.,
the Kerberos protocol) have been developed that support key
distribution in a reasonably efficient manner. However, these prior
systems and protocols fail to meet the requirements for secure
workgroup key distribution and management for use in securing data
in motion in conjunction with the secure data parser of the present
invention. Some of these requirements may include, for example: (1)
Identification Unavailable For Connection--The system should
support communication between two clients when one or both do not
have the full identity of the other. An immediate consequence of
this requirement may be to exclude per-peer session keys; (2)
Revocation--The system should be able to revoke the communication
privileges of any client. The time required for the revocation to
be completed should be user-configurable. In some embodiments,
revocation may only affect new connections, but not existing ones;
(3) Parameterized Network Chatter--This system should support a
centralized authority that can validate and distribute keys.
However, communication with this server may allow for a distributed
key to be usable or valid only for some user-configurable or
predetermined period of time; (4) Minimal Participant
State--Clients may only need to store a small amount of information
to communicate. In particular, the state stored by a client should
not include per-peer information. All of the above requirements may
be met using the systems and methods described herein.
[0168] In some embodiments, the following client functions may be
used to support the processes and systems of the present invention
at a workgroup client. The functions described below may be
implemented using software, firmware, hardware (e.g., embedded
systems), or any combination of the foregoing. Arguments in the
function below may be indicated except for "helper" arguments such
as the length field to a buffer. Also, only some notable error
codes are mentioned. In other embodiments, additional error codes,
arguments, or both, may be used.
[0169] 1. Function wa_init--This function may return type
ErrorCode, take clientld as input, and output type ctx. This
function may be used to initialize the client-side key distribution
service. The ctx variable may be initialized and hold the state on
all the keys currently in use, their versions, and other
key-specific information. This function may also set up an event
thread for handling asynchronous communications. The clientld
should be the same identifier given to the WA.
[0170] 2. Function wa_newKeyld--This function may return type
ErrorCode, take types ctx, wgKeyld, waAddress, and privateKey as
inputs, and have no output. This function may be used to add a
workgroup key ID to the ctx context for managing. waAddress may be
the network address for the WA that is responsible for this
particular ID. privateKey may be used for encrypting communication
with the WA and should be the same key provided to the WA.
[0171] 3. Function wa_teardown--This function may return type
ErrorCode, take type ctx as input, and have no output. This
function may be used to tear down all of the states managed by the
service and deallocate the memory for the context ctx. This
function may also cancel any pending requests (e.g., tickets).
[0172] 4. Fucntion wa_keyUpToDate_async--This function may return
type ErrorCode, take types ctx, wgKeyld, and callback as inputs,
and output type Ticket t. This function may be used to check that
the workgroup key identified by wgKeyld is up-to-date. There may be
no need to specify the version number in some embodiments because
the version number may be handled internally by the managing
context. This call may be asynchronous and may return immediately.
When the event loop receives the response from the server, the
event loop may call the callback function. It may then pass to this
callback function an error code as well as a status code, although
the status code may be meaningful if there was no error. If the
client is not authorized to communicate with this workgroup any
longer, callback may receive ERROR_WORKGROUP_AUTHORIZATION. If
there is no error and the key is still valid, it may receive
STATUS_KEY_OK. Otherwise, it may receive STATUS_KEY_STALE. When
this function terminates, the ticket t may serve as an identifier
for the waiting request listener.
[0173] 5. Function wa_keyRequest_async--This function may return
type ErrorCode, take types ctx, wgKeyId, and callback as inputs and
return type Ticket t. This function may be used to refresh the key
material and version for this key identifier. A call to this
function may be asynchronous and may return immediately. When the
event loop receives the response, the event loop may call the
callback function. It may pass to this callback function an error
code indicating whether the key update was successful or not. If
the client is not authorized to communicate with this workgroup any
longer, callback may receive ERROR_WORKGROUP_AUTHORIZATION. When
this function terminates, the ticket t may serve as an identifier
for the waiting request listener.
[0174] 6. Function wa_keyValidate_async--This function may return
type ErrorCode, take ctx, wgKeyId, wgKeyIDVersion, and callback as
inputs, and output type Ticket t. This function may be used to
validate a key received from another party. This function may
update its own key (as per wa_keyRequest_async) as part of the
operation. This function may also be asynchronous and may return
immediately. When the event loop receives the response, the event
loop may call the callback function. It may pass to this callback
function an error code indicating whether the key check was
successful and a status code indicating the validity of the key.
The three possible status codes may include, for example,
STATUS_KEY_OK, STATUS_KEY_STALE, and STATUS_KEY_INVALID. If the
workgroup key is not one currently managed by the context ctx, this
function may return ERROR_UNKNOWN_KEY. This error code may also be
passed to the callback function as an optimization.
[0175] 7. Function wa_currentVersion--This function may return type
ErrorCode, take ctx and wgKeyId as inputs, and output version. This
function may be used to return the current version as managed by
the context ctx for the given workgroup-key ID.
[0176] 8. Function wa_nextRefresh--This function may return type
ErrorCode, take ctx and wgKeyId as inputs and output timeLeft. This
function may be used to return the number of seconds remaining
before the key should be refreshed. This function may return 0 if
the next refresh time has already expired.
[0177] 9. Function wa_status--This function may return type, take
Ticket t as input, and output type status. This function may be
used to provide, for example, STATUS_COMPLETE or STATUS_WAITING for
the given ticket to status. If the ticket is unknown, this function
may return ERROR_UNKNOWN_TICKET.
[0178] 10. Function wa_timeWaiting--This function may return type
ErrorCode, take Ticket t as input, and output seconds. This
function may be used to provide the number of seconds that the
request has been pending to seconds.
[0179] 11. Function wa_cancel--This function may return type
ErrorCode, take Ticket t as input, and have no output. This
function may be used to cancel a pending request.
[0180] The above functions are merely illustrative. Many other
functions may be defined at a workgroup client for use in
distributing and managing workgroup keys in accordance with the
present invention. In addition, although some applications of the
secure data parser and workgroup management module are described
above, it should be clearly understood that the present invention
may be integrated with any network application in order to increase
security, fault-tolerance, anonymity, or any suitable combination
of the foregoing.
[0181] Additionally, other combinations, additions, substitutions
and modifications will be apparent to the skilled artisan in view
of the disclosure herein. For example, although many of the
processes illustrated in the figures refer to a client's secret key
and/or symmetric key cryptography, a skilled artisan will recognize
that a public/private keypair could alternatively be used in a
corresponding asymmetric cryptographic scheme.
* * * * *