U.S. patent application number 09/740444 was filed with the patent office on 2001-06-28 for cryptographic policy filters and policy control method and apparatus.
This patent application is currently assigned to Netscape Communications Corporation. Invention is credited to Elgamal, Taher, Relyea, Robert, Weinstein, Jeff.
Application Number | 20010005885 09/740444 |
Document ID | / |
Family ID | 26729277 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010005885 |
Kind Code |
A1 |
Elgamal, Taher ; et
al. |
June 28, 2001 |
Cryptographic policy filters and policy control method and
apparatus
Abstract
An apparatus for an integrated dynamic encryption and/or
decryption for use in an application includes a policy filter, a
policy filter module coupled to said policy filter, a service
module coupled to said policy filter, and a cryptographic module,
where the apparatus retrieves the cryptographic module and
configures the policy filter in accordance with the cryptographic
module and the policy filter module performs a plurality of
verification upon the cryptographic module, and further where the
service module is configured to generate a plurality of cipher
suites and the policy filter is configured to filter the plurality
of cipher suites in accordance with a predetermined policy filter
parameters to generate a plurality of filtered cipher suites.
Moreover, an apparatus for an integrated dynamic encryption and/or
decryption for use in an application includes storage means for
storing a plurality of predetermined attributes and corresponding
values, and a digital signature, a controller for controlling
selective retrieval of said plurality of attributes and values, and
said digital signature from said storage means, processing means
for selectively processing said plurality of predetermined
attributes and values, and said digital signature and in accordance
thereto, providing a supportable encryption and/or decryption level
to said application, compression means for compressing said
plurality of attributes and values and in accordance thereto
generating a compressed plurality of attributes and values for
storing in said storage means, and decompressing means for
decompressing said compressed plurality of attributes and values in
accordance to said controller retrieving said compressed plurality
of attributes and values.
Inventors: |
Elgamal, Taher; (Atherton,
CA) ; Weinstein, Jeff; (Los Gatos, CA) ;
Relyea, Robert; (Mountain View, CA) |
Correspondence
Address: |
Seong-Kun Oh
Limbach & Limbach L.L.P.
2001 Ferry Building
San Francisco
CA
94111
US
|
Assignee: |
Netscape Communications
Corporation
|
Family ID: |
26729277 |
Appl. No.: |
09/740444 |
Filed: |
December 19, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09740444 |
Dec 19, 2000 |
|
|
|
08940449 |
Sep 30, 1997 |
|
|
|
60051307 |
Jun 30, 1997 |
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Current U.S.
Class: |
713/164 ;
380/277; 713/189 |
Current CPC
Class: |
G06F 21/602
20130101 |
Class at
Publication: |
713/164 ;
713/189; 380/277 |
International
Class: |
H04L 009/14 |
Claims
What is claimed is:
1. A policy filter for configuring an application program to use
allowable cryptographic capabilities of a cryptographic module,
comprising: means for receiving an indication of a plurality of
cryptographic capability of a cryptographic module; means
responsive to a policy file for determining cryptographic
capabilities allowable to be used by the application program; and
means for providing an indication of the allowable cryptographic
capabilities to a location accessible by the application
program.
2. The system of claim 2 wherein said allowable capabilities to be
used by the application program includes a plurality of cipher
suites.
3. The system of claim 3 wherein said plurality of cipher suites
include encryption algorithms, key sizes, and parameters indicative
of the type and the strength of a plurality of cryptographic
operations.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to cryptography configuration.
More particularly, the present invention relates to method and
apparatus for controlling the use of cryptography such that
products utilizing these controls may be exported in accordance
with United States export laws, and/or imported into other
countries that place additional restrictions on the use of
cryptography.
[0003] 2. Description of the Related Art
[0004] There are many circumstances where the distribution or the
use of encryption software is regulated by governments. In some
countries, the strength of encryption that can be exported is
regulated without imposing any restrictions upon the distribution
of the encryption software within the country. For example, in the
United Sates, companies are free to distribute any type of
encryption software developed within the country for use by United
States citizens. Furthermore, United States allows unrestricted
importation of encryption technology. However, exporting of a
certain strength encryption in the United States is regulated. In
other countries, such as France, the strength of encryption that
can be used, distributed or imported is tightly regulated.
[0005] In the case where the exporting of the encryption software
is restricted, the permissible exportable encryption software are
usually limited to specific algorithms that use key sizes which are
weaker than a particular size. Previously, the encryption software
has generally been an integral part of a software application.
Therefore, to accommodate the varying degrees of allowed encryption
levels, several versions of the same application are typically
created; one version that provides strong encryption by those who
are allowed unrestricted use, and one or more versions that use
weaker encryption for those customers whose use is restricted. In
many cases, one single weaker version is created to avoid the
expense of creating and maintaining multiple versions of the same
application.
[0006] One reason that applications distributed under these
restricted rules have been required to include encryption modules
as an integral part of the software, rather than as a separate
module that can be plugged into the application, is to prevent an
encryption module that supports strong encryption from being
plugged into an application and used in a country where encryption
is restricted, and thereby enabling strong encryption with that
application.
[0007] Exportable/export strength encryption refers to encryption
algorithms and key sizes that provide relatively weak (i.e., easy
to defeat) protection of information. Presently, the United States
government allows general purpose encryption products to be
exported from the United States to other countries only if those
products utilize approved encryption algorithms and key sizes that
are weaker than a certain measure. General purpose encryption is an
application of encryption that does not limit the type or size of
the data being encrypted. The United States government places more
restrictions on software that can encrypt any kind of data than it
does on software that limits the type and size of the data being
encrypted. SSL and S/MIME are considered to be general purpose
encryption protocols because they do not place any limits on the
type or size of the data being encrypted.
[0008] By contrast, special purpose encryption is an encryption
application that limits the type and size of the data being
encrypted. The United States government will sometimes give export
permission for stronger encryption algorithms if they are limited
in use to a specific purpose and type of data (strong encryption
defined as encryption algorithms and key sizes that are stronger
(i.e., harder to defeat) than those that the United States
government usually allows to be exported for general purpose
encryption). The SET protocol is an example of an encryption
protocol that was designed to encrypt special purpose data for
purposes of performing financial transactions only.
[0009] Recently, standards have been developed that define the
interfaces between application software and modules that provide
encryption. The purpose of these standards is to facilitate the use
of Smart Cards and other hardware encryption devices. By defining a
standard interface, and allowing encryption modules to be plugged
into applications, any encryption module can be used with any
application without having to write special software to integrate
each module with each application.
[0010] The advent of these new standards presents a problem for
application developers since applications that support pluggable
encryption modules will be difficult or impossible to distribute
under the current varying government regulations. In order to
obtain the benefits of standards for pluggable encryption modules,
an approach is necessary that satisfies governments by way of
ensuring that their various levels of restrictions will be
enforced. Such an approach will allow the application to be
distributed separately from any encryption modules that it may use,
but still allow the application to restrict the use of encryption
to the permissible level.
[0011] One approach has been developed by Microsoft for their
Crypto API (CAPI) system. Applications that use CAPI may only load
encryption plugin modules that have been digitally signed by
Microsoft. Microsoft will only sign a module once the developer of
the module has agreed to abide by the governmental restrictions
when distributing the module.
[0012] However, this approach poses several new problems. First, it
requires a legal agreement between Microsoft and all developers of
encryption modules, which can be expensive and time consuming.
Another problem with the CAPI system is that it does not allow the
application to access stronger encryption algorithms that may
otherwise be available in the encryption plugin for those cases
where only special purpose encryption is being performed for higher
level of encryption transactions, and stronger encryption may be
used legally. Some applications that would benefit from or require
this type of access are: Secured Socket layer (which are exportable
cipher suites that have 40-bit secret keys still use 128-bit RC2 or
RC4S encryption, where the 40 bits of the 128-bit key are secret
while the remaining 88 bits are not.); Special purpose encryption
protocols such as SET (these protocols limit the scope and the size
of the data that they encrypt, so that most governments allow them
to use much stronger encryption algorithms and key sizes than would
be allowed for general purpose encryption); and encryption of key
material (generally, when key material is being encrypted, strong
algorithms and larger key sizes can be legally used).
[0013] As previously discussed, because the level of permissible
exportable cryptography varies depending upon the importing
country, different versions of a single application are necessary.
Also, these different versions of the same application differ in
languages used in the manuals and in the help files that are part
of the product. In the past, a separate version of the single
application was developed for each market, embodying the legally
marketable cryptographic policies, for sale and use of the
application in the target market. Each of these different versions
had to be separately built, tested, localized (translated into the
local languages), and supported. The cost of these operations is
considerably greater than if there was only one single version of
the application to serve all the markets. Having a single
application for all these markets can also reduce development and
testing time, therefore, shorting the time between development and
testing of a new application to marketing and sale.
[0014] As discussed above, to address the multiple-version issue,
some manufacturers and developers only make and sell products that
contain no cryptography, while others only make and sell products
that contain only the weaker exportable forms of cryptography, the
latter foregoing making stronger cryptography available inside the
United States (where stronger cryptography is not subject to export
regulations). There are also manufacturers and developers that make
separate version of the same program for each of the differing
markets, and bear the expense and time-to-market cost associated
with making and supporting multiple versions of the same
application/product.
[0015] With any of the aforementioned approaches, many customers
including banks and financial institutions find the weaker level of
security offered as exportable general purpose encryption to be
unacceptable for financial transactions. Additionally, building
separate programs substantially increases time and expenses in
production, quality testing, and support for the products.
SUMMARY OF THE INVENTION
[0016] In view of the foregoing, in accordance with the present
invention, policy filters are provided in which an application is
limited to accessing only those algorithms in an encryption module
that are indicated in the policy filters, even if stronger
encryption algorithms are available in the encryption module. The
policy filter in accordance with the present invention allows
anyone to develop a cryptographic plugin module without the need to
have legal agreements between the application or API developers and
the crypto module developers.
[0017] Moreover, the policy filters in accordance with the present
invention allow separate controls to be used for the different
APIs, Protocols, and Services in a system, so that the unique needs
of each market can be met. The policy filters in accordance with
the present invention are provided as a part of a system that
includes cryptographic functionality. The cryptographic
functionality includes information indicative of the cryptographic
policies such as the various levels of allowable encryption between
the different countries. The system including cryptographic
functionality could be an operating system or an application
platform such as the Netscape ONE platform as it exists in Netscape
Communicator.RTM. or SuiteSpot.RTM. servers. These systems have
cryptographic APIs, Protocols, and Services that are made available
to layered applications. For further background information on
layered applications, see pending U.S. Pat. Application Ser. No.
08/519,585.
[0018] Moreover, in accordance with another embodiment of the
present invention, there is provided a cryptographic policy file
including a cryptographic policy module. The cryptographic policy
module, which is part of an application, accesses the cryptographic
policy file when the application is executed and performs several
validity verifications on the cryptographic policy file to ensure
that the cryptographic policy file is legitimate and is being used
in the market for which it was intended. If the cryptographic
policy module determines that the cryptographic policy file passes
these tests, the cryptographic policy module then enables or
disables each of the possible forms of encryption which the
application can request according to the contents of the
cryptographic policy file.
[0019] Each of the program's cryptographic applications, for
example, SSL, S/MIME, and PKCS #12, provides a uniform interface
for turning each of its capabilities on or off, and for setting
numeric parameters (e.g., key sizes). Also, each of these
capabilities is pre-configured to a default "off" or "minimal
security" state, and remains in that state until re-configured by
the cryptographic policy module according to the contents of the
cryptographic policy file when the application is first executed.
Accordingly, a separate cryptographic policy file is provided for
each market. Therefore, a single program can legally be used and
sold in each of the aforementioned markets with varying levels of
supportable encryption, and will provide the forms of encryption
that are legally appropriate to each market according to the
cryptographic policy file supplied to the specific market.
[0020] These and other features and advantages of the present
invention will be understood upon consideration of the following
detailed description of the invention and the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 illustrates a block diagram of a system including a
policy filter in accordance with one embodiment of the present
invention.
[0022] FIG. 2 illustrates a flow chart of the initialization of the
policy filter in accordance with one embodiment of the present
invention.
[0023] FIG. 3 illustrates a flow chart of the control of capability
query through the policy filter in accordance with one embodiment
of the present invention.
[0024] FIG. 4 illustrates the control of cryptographic operation
through the policy filter in accordance with one embodiment of the
present invention.
[0025] FIG. 5 illustrates a flow chart of a cryptographic policy
module using a cryptographic policy file in accordance with one
embodiment of the present invention.
[0026] FIG. 6 illustrates a block diagram of a system including a
policy file and module in accordance with one embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] FIG. 1 illustrates a block diagram of a system including
policy filters in accordance with one embodiment of the present
invention. Various application programs--Messenger 101, the
Navigator 102, and a "Third Party" Application 103 are shown. A
plurality of policy filters are provided including a crypto API
policy filter 108, an SSL policy filter 109, an S/MIME policy
filter 110, and a key storage policy filter 111. Each of these
policy filters is associated with a corresponding service module
including a crypto API 104, an SSL 105, an S/MIME 106, and a key
storage service 107, respectively.
[0028] Referring to FIG. 1, there is also provided a policy filter
initialization module 112 which configures each of the policy
filters (including the crypto API policy filter 108, the SSL policy
filter 109, the S/MIME policy filter 110, and the key storage
policy filter 111) of the system prior to the execution of the
first cryptographic operation. There are also provided three
cryptographic plugin modules including Fortezza card 114,
cryptographic smart card 115, and a software crypto module 116.
[0029] Public key cryptography standard number 11 (PKCS #11) 113
operates as a standard interface to crypto modules. A crypto
module, a cryptographic module, or an encryption module is a
software module that provides a standard interface to low level
cryptographic services such as encryption and decryption of
data.
[0030] As will be further explained in more detail below in
conjunction with FIG. 2, when one of the applications (the
Messenger 101, the Navigator 102, or the third party application
103) is executed, the crypto plugin modules 114, 115, and 116 are
loaded and the policy filters 108, 109, 110 and 111 are configured
by the policy filter initialization module 112. Moreover, the
policy filter initialization module 112 performs conformance tests
upon the loaded crypto modules 114, 115, and 116.
[0031] Having thus initialized the policy filters 108-111 in the
manner described above, service module capabilities are next
determined as will be explained in more detail in conjunction with
FIG. 3. Thereafter, when an application program (i.e., the
Messenger 101, the Navigator 102, or a third party application 103)
calls a service module (i.e., the crypto API 104, the SSL 105, the
S/MIME 106, or the key storage service 107) to perform an operation
that involves cryptographic functions, the called service module
calls its respective policy filter (i.e., the crypto API policy
filter 108, the SSL policy filter 107, the S/MIME policy filter
110, or the key storage policy filter 111) to determine whether the
called operation is allowed. If the called operation is not
allowed, then the service module returns an error to the
application. If, however, the called operation is allowed, the
service module performs the called operation, calling the
cryptographic module when necessary, and returning the results to
the application.
[0032] FIG. 2 is a flow chart illustrating the initialization of
the policy filters in accordance with one embodiment of the present
invention. As shown, when the system of FIG. 1 begins the
initialization at step 202, the system first loads the crypto
modules (for example, the Fortezza card 114, the cryptographic
smart card 115 and the software crypto module 116) at step 203.
Loading the crypto modules entails invoking a dynamic mechanism
provided in operating systems for loading modules of code, referred
to as shared libraries or dynamic link libraries (DLLs), into an
already running application program. In this manner, the crypto
module code is dynamically loaded by the operating system into the
running application program. The system then configures the policy
filters at step 204.
[0033] The policy filter initialization module 112 (FIG. 1) then
performs conformance tests on the crypto modules at step 205. The
conformance tests involve requesting the crypto module to perform a
cryptographic function, then comparing the results to the result of
a known compliant implementation of the same algorithm. If, at step
206, the conformance tests performed by the policy filter
initialization interface 112 is successful, then a result of
success is returned to the system at step 208. If, however, the
conformance test performed at step 206 is not successful, (i.e.,
the crypto module does not correctly implement the algorithms
and/or key sizes configured), then a result of failure is returned
to the system at step 207, followed by a disabling of the crypto
module at step 209 which failed the conformance test.
[0034] In the manner described above, the initialization of the
policy filter prevents a cryptographic module from incorrectly
stating its capabilities in order to bypass the system's controls.
Accordingly, the conformance tests in accordance with the present
invention are sufficiently broad to ensure that the cryptographic
module is correctly implementing the algorithms and that the key
sizes advertised therefrom are indeed being used.
[0035] FIG. 3 is a flow chart illustrating the control of
capability query through a policy filter (i.e., one of the policy
filters 108-111 of FIG. 1) in accordance with one embodiment of the
present invention. As shown, when the query begins at step 301, the
application initially queries the capabilities (i.e., cipher suites
that it supports) of the service modules at step 302. Accordingly,
at step 303, a corresponding service module (which is one of the
service modules 104-107 of FIG. 1) generates a full list of cipher
suites that it supports and passes this list to the policy filter.
In this regard, a cipher suite is a collection of encryption
algorithms, key sizes, and parameters that fully specifies the type
and the strength of a particular cryptographic operation.
[0036] At step 304, the policy filter applies its configuration
parameters to filter out or remove unauthorized cipher suites from
the list received from the service module at step 303. After
filtering at step 304, the policy filter then returns the filtered
list of cipher suites to the service module at step 305, which, in
turn, returns the filtered list of cipher suites to the
application. With the list of filtered (or authorized) cipher
suites, the application causes a cryptographic operation to be
performed in accordance with FIG. 4.
[0037] Referring now to FIG. 4, the cryptographic operation is
initiated by an application at step 401. The application calls a
service module to request an operation involving cryptographic
functions at step 402. At step 403, the service module calls its
corresponding policy filter to determine whether the called
operation is allowed. At step 404, if the called operation is not
approved by the corresponding policy filter, then the service
module returns an error to the application at step 405. On the
other hand, if, at step 404, the called operation is approved, then
at step 406, the service module performs the called operation,
calling the cryptographic module as necessary. Thereafter, the
service module, at step 407, returns the operation results to the
application.
[0038] In accordance with the present invention, the policy filters
are configured by the system as shown in FIG. 1 before the first
cryptographic operation is performed. The policy filter module
provides a configuration interface for this purpose. The policy
filters will have a default configuration, which may be to disable
all operations, or to allow a subset of operations that are
generally allowed by the most restrictive configurations. There are
numerous mechanisms that the system may use to determine the
correct configuration parameters for the policy filters. Some
examples include, but are not limited to, compiling the parameters
into the system or reading the parameters from a protected file
(e.g., such as a digitally signed file). It is to be noted that
some application programs may be compiled into one system, while
other application programs may by dynamically loaded.
[0039] The policy filter module also performs conformance tests on
the cryptographic module to ensure that the crypto module is
correctly implementing the algorithms and key sizes that it is
advertising. This is to prevent a cryptographic module from
incorrectly stating its capabilities in order to bypass the
system's controls. The sets of tests are broad enough to ensure
that the module is correctly implementing the algorithms and that
the key sizes being advertised are indeed being used.
[0040] As illustrated above, the policy filters in accordance with
the present invention are associated with each service module that
will use the cryptographic services provided by the cryptographic
module. The policy filters control both the capabilities advertised
by the service modules and the operations the service modules are
allowed to perform. The process of requesting the capabilities of a
service module involves first the application querying the service
module for the list of cipher suites that it supports. In response,
the service module passes its list of supported cipher suites to
its policy filter. With the list of supported suites, the policy
filter applies its configuration parameters to filter the list of
cipher suites. Having filtered the list of cipher suites, the
policy filter returns the filtered list of cipher suites to the
service module, which, then returns the filtered list of cipher
suites to the application.
[0041] In accordance with another embodiment of the present
invention, there are provided cryptographic policy files comprising
a set of ASCII-coded Attribute-Value pairs which may optionally be
compressed, and a digital signature on the set of Attribute-Value
pairs. The set of Attribute-Value pairs is a series of lines of
plain ASCII text. Each line contains the name of an attribute of
the cryptographic policy, followed by a colon, optionally some
space, and the value of that attribute. A value may be in the form
of a sequence (or "string") of printable ASCII characters, an
integer number, or a "truth expression", that is, one of the words
"true", "false" or "conditional." The following Table 1 illustrates
the attribute name, its type and purpose, all of which are required
in each cryptographic policy file.
1TABLE 1 Attribute in Cryptographic Policy Files Attribute Name
Type Purpose POLICY-BEGIN-HERE String Name the policy (market) for
this file, for example, "Export Policy." Software-Version String
Identifies the program, its version number, and the localization
(language) incorporated in the program, for example, "Mozilla/4.0P3
[fr]."
[0042] All other attributes are dependent upon the cryptographic
capabilities of the program. Each and every cryptographic
capability of the program that is subject to the export laws of the
United States, or to the import laws of other countries, must be
named as an attribute of the cryptographic policy in each of the
cryptographic policy files produced for that program. The following
Table 2 illustrates a sample Attribute-Value pairs incorporated
into a program.
2TABLE 2 Sample Attribute-Value Pairs POLICY-BEGINS-HERE: Export
policy Software-Version: Mozilla/4.0P3 [fr] MAX-GEN-KEY-BITS: 512
PKCS12-DES-EDE3: false PKCS12-RC2-128: false PKCS12-RC4-128: false
PKCS12-DES-56: false PKCS12-RC2-40: true PKCS12-RC4-40: true
PKCS12-NULL: true SSL2-RC4-128-WITH-MD5: false
SSL2-RC2-128-CBC-WITH-MD5: false SSL2-DES-168-EDE3-CBC-WITH-MD5- :
false SSL2-DES-56-CBC-WITH-MD5: false
SSL2-RC4-128-EXPORT40-WITH-MD5: true SSL2-RC2-128-CBC-EXPORT40-WI-
TH-MD5: true SSL3-FORTEZZA-DMS-WITH-FORTEZZA-CBC-SHA: false
SSL3-FORTEZZA-DMS-WITH-RC4-128-SHA: false
SSL3-RSA-WITH-RC4-128-MD5: conditional SSL3-RSA-WITH-3DES-EDE-CBC-
-SHA: conditional SSL3-RSA-WITH-DES-CBC-SHA: false
SSL3-RSA-WITH-RC4-40-MD5: true SSL3-RSA-WITH-RC2-CBC-40-MD5: true
SSL3-FORTEZZA-DMS-WITH-NULL-SHA: false SSL3-RSA-WITH-NULL-MD5: true
SMIME-DES-EDE3: false SMIME-RC2-CBC-128: false
SMIME-RC5PAD-64-16-128: false SMIME-DES-CBC: false
SMIME-RC2-CBC-64: false SMIME-RC5PAD-64-16-64: false
SMIME-RC2-CBC-40: true SMIME-RC5PAD-64-16-40: true
[0043] The set of attribute-value pairs in the cryptographic policy
file in accordance with the present invention can also be
compressed to reduce its size and to make the contents less
apparent to others.
[0044] As previously explained, the second component of the
cryptographic policy file is the digital signature. A digital
signature is a block of data (a very large number) computed
mathematically from another set of data (the "signed data") using
the signer's "private key". The digital signature may be used to
verify that the signed data has not been altered in any way since
it was signed, and that it was genuinely signed 10 by the party
named in the signer's certificate. The digital signature affirms
the authenticity and the integrity of the signed data, which, in
accordance with the present invention, is the string of
Attribute-Value pairs.
[0045] The digital signature is stored in the file as a part of a
"signed-data content type" block, as defined in Public Key
Cryptography Standard #7 (PKCS #7). A signed-data content type
block is a block of data in the format standardized for the
representation of digital signatures. It contains a digital
signature, the certificate used to verify the signature (the
"signer's certificate"), the chain of Certification Authority (CA)
certificates used to validate the signer's certificate, and
optionally the data that was signed by the digital signature (the
"signed data"). An "external Signature" is a signed-data content
type data block containing a digital signature, the signer's
certificate, and a certificate chain, but not containing the signed
data.
[0046] A Certification Authority is an entity that issues (or
signs) digital certificates Furthermore, a Certificate Chain is a
list of certificates, each one (except the last) issued, signed,
and authorized by the party identified in the succeeding
certificate in the list. The Certificate Chain is used to determine
the validity and veracity of the first certificate in the chain,
which is usually the certificate of a document's signer. The final
certificate in the chain must be that of a trusted party for the
chain to have validity.
[0047] Accordingly, the Attribute-Value pairs and the External
signature are stored in an archive file known as a "jar" file. The
jar file provides a convenient mechanism in which to store multiple
components together in one file. Moreover, in accordance with the
present invention, the jar-file utility programs provide a
convenient method to compress the selected components, and to sign
the components. It is to be noted, however, in accordance with
another embodiment of the present invention, the Attribute-Value
pairs are stored within the PKCS #7 signed data content type block,
in which case the PKCS#7 signed data content type block is not said
to be an External signature, and the policy file consists solely of
the PKCS#7 signed data content type block.
[0048] A Private Key is a block of data (actually a very large
number) used to sign (make a digital signature for) another
document. The private key must be kept secret by the signer if the
signatures it generates are to be trusted. On the other hand, a
public key is a block of data (actually a very large number) used
to verify the digital signature on a digitally-signed document.
Unlike the Private Key, the Public Key need not be kept secret, and
may be distributed to the public. A Public Key is usually conveyed
in a signed document called a certificate. A certificate is a
document containing a signer's name and public key, and the
signature of a third party, vouching for the accurate
identification of the party named in the certificate. A certificate
is used to obtain the public key needed to verify a digital
signature made by the party named in the certificate.
[0049] Furthermore, as illustrated above, in accordance with the
present invention, the cryptographic policy module in the program
performs its services when the user begins the program's execution
on the user's computer. It also performs its services whenever the
user attempts to change the configuration of the cryptographic
functions within the program.
[0050] As shown in FIG. 5, when the program begins executing, the
cryptographic policy module first reads the cryptographic policy
file into the computer's memory (as shown in step 501). Then, the
policy module verifies the digital signature on the Attribute-Value
pairs at step 502. At step 503, the module verifies that the
digital signature is a genuine digital signature of the product's
manufacturer by determining that one or more of the certificates in
the digital signature's certificate chain is the certificate issued
by the manufacturer for that very purpose. This is accomplished in
the present invention by comparing to a "built-in" CA certificate.
At step 504, a further verification is performed which confirms
that the Software-Version Attribute value string matches the
version of the running program. Finally, at step 505 yet another
verification is performed, confirming that the localization
(language) specified in the Software-Version Attribute value string
matches the localization in use by the running program.
[0051] If the verification in any of the above steps 502-505 fails,
then the entire content of the cryptographic policy file is ignored
at step 506, and the program behaves according to its default set
of encryption rules, which generally is the most restrictive set of
cryptographic capabilities in the program. If, on the other hand,
all of the verification steps 502-505 are successful, then the
cryptographic policy module proceeds to step 507 where the
cryptographic software in the running application program is
configured for each and every one of the cryptographic capabilities
listed in a set of Attribute-Value pairs. The capabilities that are
enabled or disabled according to a "truth expression" are enabled
or disabled according to the expression in the relevant
Attribute-Value pair in the corresponding policy file. The
capabilities that vary by number (for example, key length) are set
to the numeric value in the relevant pair. Any values not specified
are left in their default configuration, which is generally off, or
using the smallest numeric value.
[0052] FIG. 6 illustrates a block diagram of a system including a
policy file and a cryptographic policy control module in accordance
with one embodiment of the present invention. In such a system,
there is provided an application program such as the Netscape
Communicator.RTM. 601 which includes a plurality of applications
such as the Navigator SSL 602, the Messenger S/MIME 603, and the
Key Storage PKCS #12 603 as three cryptographic applications. There
is also provided a cryptographic policy control module 605 which
configures each of the three cryptographic applications, Navigator
SSL 602, the Messenger S/MIME 603, and the Key Storage PKCS #12 603
in accordance with a predetermined data string received from a
policy file 606. Policy files can be used to directly configure a
trusted application, or can be used as the mechanism to configure
policy filters as described in the first embodiment of the present
invention.
[0053] Also, in accordance with the present invention, the
application's user is generally allowed to select preferences among
the various cryptographic capabilities available, and may elect to
disallow certain of the approved capabilities, or to re-enable
capabilities that he has previously disallowed. In this manner, the
user may alter those preferences while the program is running, When
the user attempts to do so, the cryptographic policy module is
again used to ensure that the user cannot enable any capabilities
that are disallowed by the cryptographic policy file.
[0054] In this manner, according to the present invention, a single
program can be made and sold in all markets. The manufacturer
spends only as much production, testing and support as a single
program requires, and the program provides stronger encryption
where it is legally allowed.
[0055] Various other modifications and alterations in the structure
and method of operation of this invention will be apparent to those
skilled in the art without departing from the scope and spirit of
the invention. Although the invention has been described in
connection with specific preferred embodiments, it should be
understood that the invention as claimed should not be unduly
limited to such specific embodiments. It is intended that the
following claims define the scope of the present invention and that
structures and methods within the scope of these claims and their
equivalents be covered thereby.
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