U.S. patent application number 13/688817 was filed with the patent office on 2013-04-04 for method for certifying and verifying digital web content using public cryptography.
This patent application is currently assigned to Reuters Limited. The applicant listed for this patent is Reuters Limited. Invention is credited to James Matthew Butler, Mark Anthony Curtis, Nicholas Fulton, David Parrott, Miles Jonathan Whitehead, Hui Wu.
Application Number | 20130086387 13/688817 |
Document ID | / |
Family ID | 9885560 |
Filed Date | 2013-04-04 |
United States Patent
Application |
20130086387 |
Kind Code |
A1 |
Fulton; Nicholas ; et
al. |
April 4, 2013 |
Method for Certifying and Verifying Digital Web Content Using
Public Cryptography
Abstract
There is provided a method of, computer programs for and
apparatus for providing and accessing digital content such as a
news item. A news provider generates a news item, creates a
digitally signed version of the news item and packages them
together with a digital certificate issued by a certificate
authority containing the public key required to decrypt the
digitally signed version. The package is posted to a server and is
transmitted, or made available or transmission, over a public data
network together with a computer program for verifying the news
item. A receiving party receives, over the public data network, the
package at a client device and is provided with means for
launching, and if necessary first downloading, the verifying
program. The verifying program uses the public key contained in the
certificate to verify the digitally signed news item. Before being
first used to verify a news item, the verifying program receives a
shared secret from the receiving party which is stored locally to
the client device and is used by the verifying program to confirm
that it performed the verification process.
Inventors: |
Fulton; Nicholas; (New York,
NY) ; Butler; James Matthew; (Northampton, GB)
; Curtis; Mark Anthony; (Compton, GB) ; Parrott;
David; (Kent, GB) ; Whitehead; Miles Jonathan;
(Middlesex, GB) ; Wu; Hui; (Essex, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Reuters Limited; |
London |
|
GB |
|
|
Assignee: |
Reuters Limited
London
GB
|
Family ID: |
9885560 |
Appl. No.: |
13/688817 |
Filed: |
November 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10203743 |
Apr 24, 2003 |
8352379 |
|
|
PCT/GB01/00345 |
Jan 29, 2001 |
|
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|
13688817 |
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Current U.S.
Class: |
713/176 |
Current CPC
Class: |
G06F 21/10 20130101;
H04L 9/3247 20130101; G06F 2221/2115 20130101; G06F 2211/008
20130101; G06Q 20/401 20130101 |
Class at
Publication: |
713/176 |
International
Class: |
H04L 9/32 20060101
H04L009/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2000 |
GB |
0003365.4 |
Claims
1. One or more non-transitory computer readable storage media
storing executable instructions that, when executed, cause a system
to perform a method of verifying displayable digital content, said
method comprising: receiving from a user, information corresponding
to a shared secret between the user and a verification application;
subsequent to receiving the shared secret, receiving a request from
the user to verify an item of displayable digital content;
verifying the item of displayable digital content; and displaying a
verification message to the user, said verification message
comprising an indication of whether or not the item of displayable
digital content was successfully verified, and further causing the
shared secret to be displayed to the user to prove the message
originated from the verification application.
2. The one or more computer readable media of claim 1, wherein the
shared secret comprises an image selected by the user.
3. A method comprising: receiving by a verifying program executing
on a client computer, at a first time, an item of displayable
digital content from a server computer; the verifying program
performing verification of the item of displayable digital content;
the verifying program receiving user input, at a second time
earlier than the first time, a shared secret data item, the shared
secret data item including information that is a secret to and
shared between a user and the verifying program; the verifying
program storing the shared secret data item; the verifying program
generating and displaying a message comprising the shared secret
data item and indicating whether the item of displayable digital
content is verified or not, said shared secret serving to prove the
message originated from the verifying program.
4. The method according to claim 3, wherein the verifying program
is received over a public data network by the client computer and
is executed on said client computer.
5. The method according to claim 4, wherein the item of digital
content is received over a public data network by the client
computer together with a user interface component for commencing
execution of the verifying program.
6. The method according to claim 4, wherein the item of digital
content is displayed by the client device using a browser, and the
verifying program is a plug-in for said browser.
7. The method according to claim 4, wherein the shared secret data
item provided by the user is stored locally to the client
device.
8. The method according to claim 3, wherein the item of digital
content comprises a news item.
9. The method according to claim 3, wherein the verifying program
is provided with an encrypted version of the item of displayable
digital content and, to verify the item of displayable digital
content, the verifying program decrypts the encrypted version and
compares the result to the item of displayable digital content.
10. The method according to claim 3, wherein the verifying program
is provided with a digital signature of the item of displayable
digital content and, to verify the item of displayable digital
content, the verifying program decrypts the digital signature and
compares the result to the item of displayable digital content.
11. The method according to claim 3, wherein the item of
displayable digital content is provided in encrypted form only and,
to verify the item of displayable digital content, the verifying
program decrypts the item of displayable digital content.
12. A non-transitory computer-readable storage medium containing
computer-readable instructions that, when executed by a processor
at a client device, perform a method of verifying an item of
displayable digital content, the instructions comprising:
receiving, at a first time, an item of displayable digital content;
verifying the item of displayable digital content; querying, at a
second time earlier than the first time, a user for a shared secret
data item, the shared secret data item including information that
is a secret to and shared between the user and a verifying program;
storing the shared secret data item; and generating a message
comprising the shared secret data item and indicating to the user
whether the item of displayable digital content is verified or not,
said shared secret serving to prove the message originated from the
verifying program.
13. The computer-readable medium according to claim 12, wherein the
computer-readable instructions are adapted to be receivable over a
public data network by the client device and executable on the
client device.
14. The computer-readable medium according to claim 13, wherein the
item of displayable digital content is configured to be received
over a public data network by the client device together with a
user interface component for commencing execution of the
computer-readable instructions.
15. The computer-readable medium according to claim 13, wherein the
computer-readable instructions are configured to be a plug-in for a
browser.
16. The computer-readable medium according to claim 13, wherein the
shared secret data item obtained from the user is stored locally to
the client device.
17. The computer-readable medium according to claim 12, wherein the
item of displayable digital content comprises a news item.
18. The computer-readable medium according to claim 12, arranged to
receive an encrypted version of the item of displayable digital
content and to verify the item of displayable digital content by
decrypting the encrypted version and comparing the result with the
item of displayable digital content.
19. The computer-readable medium according to claim 12, arranged to
receive a digital signature of the item of displayable digital
content and to verify the item of displayable digital content by
decrypting the digital signature and comparing the result with the
item of displayable digital content.
20. The computer-readable medium according to claim 12, arranged to
receive the item of displayable digital content in encrypted form
only and to verify the item of displayable digital content by
decrypting the item of displayable digital content.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a U.S. National Phase Application under 35 U.S.C.
.sctn.371. Applicants claim the benefit of PCT/GB01/00345 filed
Jan. 29, 2001, published in English under PCT Article 21(2), which
claims priority to Great Britain Application 0003365.4, which was
filed Feb. 14, 2000. The entire contents of PCT/GB01/00345 and
0003365.4 are incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates generally to methods of, computer
programs for, and apparatus for providing and accessing digital
content. More particularly, this invention relates to, but is not
limited to, a method of and computer programs for transmitting,
making available for transmission, accessing, or receiving content
over a public data network such as the Internet.
BACKGROUND
[0003] Public key infrastructure (PKI) decryption and verification
capabilities are built into commercially available browsers such as
Netscape Navigator.TM. and Microsoft Internet Explorer.TM..
Microsoft Authenticode.TM. is a prior art system for securing the
distribution of program code over the Internet which uses PKI (see
"Software Publisher Digital IDs for Microsoft Authenticode
Technology" at
http://www.verisign.com/rsc/gd/dev/authenticode/intro.html). The
functioning of Microsoft Authenticode.TM. will be discussed in
detail below with reference to FIG. 1.
[0004] FIG. 1 is a schematic diagram of the prior art system used
by Microsoft Authenticode.TM. for distributing executable code. The
diagram shows three main parties: a publisher 100 an end user 300
and a certificate authority 200. To publish software over the
Internet using Microsoft Authenticode.TM., publisher 100 must first
apply to certificate authority 200 for a private and public key
pair and for a certificate. Certificate authorities, such as
Verisign Inc., are in the business of providing private and public
key pairs to receiving parties. Moreover, they are responsible for
checking the bona fides of their receiving parties and for
providing digital certificates which may be provided as proof that
the public key belongs to the receiving party and not a third
party. On successful application, publisher 100 is provided with a
private key 102 and a certificate 104 by certificate authority 200.
Certificate 104 contains the name 106 of the publisher, a public
key 108 provided to the publisher and a digital signature 110 from
certificate authority 200 computed over both name 106 and public
key 108. Certificate authority 200 generates digital signature 110
using its own private key 202, of which the corresponding public
key 204 is made widely available to end users by being
pre-installed in browsers such as Netscape Navigator.TM. and
Microsoft Internet Explorer.TM.. This digital signature 110 serves
to confirm that public key 108 contained in certificate 104 belongs
to publisher 100. For a detailed explanation of certificate
authorities and digital certificates see "Internet Cryptography" by
Richard E. Smith, 1997, published by Addison Wesley Longman, Inc.,
in particular chapter 12.
[0005] Having developed software 112, publisher 100 encrypts the
software using his/her private key 102 to generate an encrypted
version 114. Unencrypted software 112, encrypted software 114 and
certificate 104 are then bundled together to form a package 116.
This package is made available for downloading by placing it on a
web server 118. End user 300, who downloads package 116 from web
server 118, is able to authenticate software 112 as follows.
Pre-installed in the end user's browser is public key 204 belonging
to certificate authority 200. Using this, the end user is able to
confirm that public key 108 contained in certificate 104 belongs to
publisher 100. This is because the browser is able to decrypt
digital signature 110 using public key 204 and compare the result
with name 106 and public key 108 and because certificate 104 was
signed by certificate authority 200, which the browser trusts.
Using public key 108 obtained from certificate 104, the browser is
able to decrypt encrypted version 114 of software 112 and compare
it to the unencrypted version of the software also provided. If the
two match, the browser knows that software 112 originates from
publisher 100 and, furthermore, that it has not been modified since
being encrypted. Thus, end user 300 is able to authenticate the
source and integrity of software 112.
[0006] One disadvantage with the approach taken by Microsoft
Authenticode.TM. is that it does not offer security from the
program code provider directly--i.e. it does not allow the program
code provider to act as a sole certificate authority or a low level
certificate authority within a hierarchical certification system
(see below for an explanation of these terms). One result of this
disadvantage is that it does not allow the program code provider to
arrange a level of security appropriate for its own purposes, the
type of program code provided or the requirements of its receiving
parties. A further result is that it does not engender trust of the
program code provider directly since the authentication process
appears to the receiving party to bear no relation to the program
code provider but rather to Microsoft.TM..
[0007] N Islam et al `A Flexible Security Model for Using Internet
Content` IBM Thomas J. Watson Research Center Publication, 28 Jun.
1997, XP 002138803 describes a system for downloading content over
an untrusted network, such as the Internet, and for controlling its
use on a client device, content is stamped using digital signatures
and analysed by a stamped content usage system to verify the
identity of the creator of the content and to verify that it has
not been modified.
[0008] The present invention addresses in general the security
problems of providing content over the Internet identified above as
well as the particular disadvantages of the approach taken by
Microsoft Authenticode.TM. identified above. One objective of the
present invention is to provide an easy to use system for providing
verifiable content over a public data network such as the Internet.
A further or alternate objective of the present invention is to
provide a system for the provision of a news service over a public
data network such as the Internet.
SUMMARY OF THE INVENTION
[0009] A method of verifying an item of digital content, the method
comprising the steps of:
[0010] providing, at a first time, an item of digital content to a
verifying program;
[0011] the verifying program performing verification of the item of
digital content; and
[0012] the verifying program presenting a message to a user
indicating whether the item of digital content is verified or
not;
[0013] characterised in that:
[0014] the user provides, at a second time earlier than the first
time, a data item to the verifying program, the verifying program
stores the data item, and the data item, or data derived from the
data item, is included in the message to indicate to the user that
the item of digital content was verified by the verifying
program.
[0015] According to a second aspect of the present invention, there
is provided a computer program for verifying an item of digital
content, the computer program being arranged to:
[0016] receive, at a first time, an item of digital content;
[0017] verify the item of digital content; and
[0018] present a message to the user indicating whether the item of
digital content is verified or not;
[0019] characterised in that:
[0020] the computer program is arranged to query, at a second time
earlier than the first time, a user for a data item, and to store
the data item, and in that the data item, or data derived from the
data item, is included in the message to indicate to the user that
the item of digital content was verified by the computer
program.
[0021] According to a third aspect of the present invention, there
is provided a method of providing a user with a verifiable item of
digital content, the method comprising the following steps:
[0022] displaying, on a display of a client device, an item of
digital content; characterised by:
[0023] displaying, on the display of the client device, a user
interface, operable by a user of the client device to commence
execution, at the client device, of a computer program for
verifying the item of digital content.
[0024] According to a fourth aspect of the present invention, there
is provided one or more data packages comprising:
[0025] data representing an item of digital content, capable of
being displayed on the display of a client device;
[0026] characterised in that:
[0027] the one or more data packages comprise data representing a
user interface, displayable on the display of the client device,
and operable by a user of the client device to commence execution,
at the client device, of a computer program for verifying the item
of digital content.
[0028] Because news is essentially factual content which, although
of limited currency, is often of significant economic value,
fraudulent third parties are often known to attempt to make
financial or other gain from the dissemination of false news. As
the perceived value of news depends much on its source, a third
party may gain most by the impersonation, modification or
substitution of content from a trusted news service. For instance,
with the provision of financial news, such as stock market news,
third parties may gain by disseminating misleading or false
information whilst masquerading as the trusted news service. On the
other hand, susceptibility to this kind of fraudulent activity
could have damaging consequences for the reputation of a provider
of news service. The above aspects of the invention are intended to
provide ways to reduce such risks.
[0029] There now follows, by way of example only, a detailed
description of preferred embodiments of the present invention in
which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic diagram showing the functioning of an
authentication system of the prior art.
[0031] FIG. 2 is a schematic diagram showing the functioning of the
verification system of the present invention.
[0032] FIG. 3 is a print out of a web page showing a news item and
means for commencing execution of the verification program of the
present invention.
[0033] FIG. 4 is a flow diagram representing the procedure followed
by the verifying program of the present invention.
[0034] FIG. 5 is a print out of a web page showing the news item
and a message verifying the news item according to the present
invention.
[0035] FIG. 6 is a print out of a web page showing a bogus news
item and a message indicating that the news item has been modified
according to the present invention.
[0036] FIG. 7 is a print out of a web page showing the original
unmodified news item according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] PKI techniques are well known to those skilled in the art
and generally depend on the fact that certain mathematical
computations that are easy to compute in one direction are
extremely difficult to compute in the other direction. The present
invention is based on the algorithm developed by Ron Rivest, Adi
Shamir, and Len Adelman of the Massachusetts Institute of
Technology, known by those skilled in the art as the RSA algorithm,
which relies on the fact that it can be relatively easy to multiply
large prime numbers together but almost impossible to factor the
resulting product.
[0038] PKI techniques, such as the RSA algorithm, allow pairs of
keys to be generated which can be used to encrypt data or to
digitally sign data. One of the keys is called a "public key" and
the other a "private key". The private key is kept secret whereas
the public key can be distributed freely. Data encrypted using the
public key can only be decrypted by using the private key. This
provides a mechanism whereby data can be transmitted over public
networks in secret and can only be decrypted by the holder of the
private key. Conversely, data encrypted using the private key can
be decrypted by anyone holding the public key, but, crucially, any
data which can be decrypted by the public key can only have been
encrypted using the private key. This provides a mechanism whereby
the holder of the private key can digitally sign data for
transmission over a public network in such a way that anyone who
holds the public key can verify that the data originates from the
holder of the private key and that the data has not been modified
since encryption. For a detailed explanation of PKI techniques and
the RSA algorithm, see "Internet Cryptography" by Richard E. Smith,
1997, published by Addison Wesley Longman, Inc., in particular
chapter 9. The computer programs of the present invention have been
developed using application program interfaces (APIs) providing
PKI, namely, the Baltimore PKI-Plus.TM. develops toolkit (see
http://www.baltimore.com).
First Embodiment
[0039] FIG. 2 is a schematic diagram of a first embodiment of the
present invention. A news provider 400 first applies to a
certificate authority 200 to be provided with a private key 402 and
a digital certificate 404 containing the name 406 of the news
provider 400, the public key 408 corresponding to private key 402,
and the digital signature 410 of certificate authority 200, as has
been described above. News provider 400 generates a plain text news
item, stored on a news server (not shown), and presents it in a
browser-readable page of a format such as hyper-text mark-up
language (HTML) or extensible mark-up language (XML) to form
marked-up news item 412. News provider 400 encrypts the news item
using its private key 402 thus generating an encrypted version 414
of the news item.
[0040] Unencrypted news item 412, encrypted version 414 and
certificate 404 are then bundled together to form a package 416
which is posted to a web server 418 for access by receiving
parties. Also posted to web server 418 is a verifying program 420,
the function of which is described in detail below. A receiving
party 500, who wishes to access news item 412, first downloads
package 416 from web server 418. The receiving party may then make
use of the unencrypted news item without any verification if he/she
desires. However, receiving party 500 may wish to verify that news
item 412 was generated by news provider 400 and that it has not
been modified. To do this, the receiving party downloads verifying
program 420 from web server 418 and stores it locally, if he/she
has not already done so in respect of a previous news item
accessed.
[0041] Receiving party 500 downloads package 416 containing news
item 412 using a browser application such as Netscape Navigator.TM.
or Microsoft Internet Explorer.TM.. The browser-readable page
includes a link or other suitable means for downloading and
launching verifying program 420. Preferably, this takes the form of
a part of the browser-readable page comprising the text "Click here
to verify" which when clicked on by the receiving party activates
executable code embedded in the browser-readable page which first
checks whether verifying program 420 has already been downloaded.
If it has, execution of verifying program 420 is commenced
immediately. If not, verifying program 420 is first downloaded from
web server 418 before commencing execution. The executable code
embedded in the browser-readable page is implemented using a
Java.TM. applet or Java Script.TM.. FIG. 3 shows a web page 700 as
displayed using a browser which comprises a news item 702 and a
link 704 for downloading and/or launching verifying program
420.
[0042] Preferably, verifying program 420 takes the form of a
plug-in which interoperates with the receiving party's browser.
With Microsoft Internet Explorer.TM., the plug-in verifying program
420 is implemented as an ActiveX.TM. control or component. The
verifying program is stored locally to the receiving party browser
and generally needs only to be downloaded once, i.e. when the
receiving party user first requests verification of the news item
412. Preferably, the verifying program 420 is itself downloaded in
a verifiable manner using digital signature techniques for
distributing program code such as Microsoft Authenticode.TM.
described above with reference to FIG. 1.
[0043] Verifying program 420 is separate from news item 412 and
package 416 and, further, that it is downloaded independently. This
is because a third party attempting to impersonate news provider
300 may create a browser-readable page containing its own news item
together with a bogus verifying element which gives the illusion
that the news item originates from the trusted news provider and
that it has not been modified. However, despite having downloaded
verifying program 420 independently of package 416, there remains
the possibility that a third party impersonating news provider 400
makes a browser-readable page available to receiving party 500,
which contains a bogus verifying link resembling the news
provider's link for launching or downloading verifying program 420.
The third party may have arranged for the bogus link to provide a
false verification of the news item. For instance, the bogus link
may cause the execution of an embedded Java.TM. applet or Java.TM.
script which mimics the operation of verification program 420 but
which obviously, does not and cannot perform a bona fide
verification.
[0044] To prevent this type of activity fooling receiving parties
into believing they have received bona fide news from a trusted
news provider, an extra level of security is provided. This extra
level of security is provided by requiring receiving party 500 to
enter a shared secret 502 at the request of verifying program 420
before it is first used to verify the news item. The shared secret
can be any form of information, data or code entered by the
receiving party user and is stored locally to the client device,
preferably in an encrypted format. It is a shared secret in the
sense that it is secret to and shared between the receiving party
and the verifying program. Verifying program 420 displays shared
secret 502 to the receiving party upon verification of the news
item to prove that it is the original verifying program and not a
bogus link in a page made available by a third party. A bogus link
in a page provided by a third party cannot fool a receiving party
that it is the original verifying program because it will not know
of or have access to shared secret 502. Even if the third party is
aware that shared secrets are used, the bogus link, when
implemented as an embedded Java.TM. applet or Java.TM. script will,
generally, not have access to the client device where shared secret
502 is stored. In any event, it will not have the key necessary to
decrypt the encrypted shared secret.
[0045] The process of verifying news item 412 using the verifying
program will be described in detail later in this document.
Second Embodiment
[0046] According to a second embodiment of the present invention,
which is a variant of the first embodiment described above, package
416 contains one or more certificates (not shown) in addition to
certificate 404. These additional certificates are part of a
certification hierarchy in which certificate authority 200 is at
the top level and provides the root public key, i.e. public key 204
and certificate 404 is at the lowest level and provides the public
key necessary for verification--i.e. public key 408. Public key 204
is used by verifying program 420 to validate an additional
certificate at one level lower in the hierarchy, which certificate
may itself contain a public key for validating a further additional
certificate, and so on down the hierarchy. The penultimate
certificate contains the public key for validating certificate 404.
As with the first embodiment, certificate 404 contains public key
408 corresponding to private key 402 which belongs to news provider
400. Again, as with the first embodiment, news item 412 is
encrypted using this private key to generate encrypted version 414,
and verifying program 420 uses public key 408 to decrypt encrypted
version 414 when performing its verification.
Third and Fourth Embodiments
[0047] According to third and fourth embodiments of the present
invention, which are, respectively, variants of the first and
second embodiments described above, news provider 400 is itself a
certificate authority and generates its own provate key 402, public
key 408 and certificate 404 for use as described above.
Furthermore, news provider 400 also owns private key 202, which it
uses to sign certificate 404, and public key 204 which is installed
in client devices for validating certificate 404.
[0048] FIG. 4 is a flow diagram representing the procedure followed
by verifying program 420 for verifying news item 412 provided in
package 416 according to all the embodiments described above. The
procedure starts at step 600. At step 602, the verifying program
determines whether receiving party 500 has provided a shared secret
which is still valid. If not, at step 604 receiving party 500 is
queried for a shared secret and the verifying program continues to
step 606. For example the receiving party may enter `The cat sat on
the mat` as his/her shared secret. Preferably, known methods of
managing passwords are used to by verifying program 420 to manage
shared secrets. In one variation of the embodiments of the present
invention, shared secrets remain valid for a predetermined period
after which a new shared secret is required from the receiving
party. In another variation, shared secret 502 remains valid for
the lifetime of verifying program 420.
[0049] If receiving party 500 has provided a shared secret which is
still valid, verifying program 420 proceeds to step 606 at which
the certificate at the top level in the certificate hierarchy is
checked using the root public key installed in the receiving party
browser. In the first and third embodiments, there will be only one
certificate provided in package 416--i.e. certificate 404--and this
will thus be the toop level certificate. At step 608 the verifying
program checks whether the certificate is valid. The process of
validating the top level certificate involves decrypting the
digital signature of the certificate using root public key 204 and
comparing the results obtained with the name and public key
contained in the certificate. If they do not match, verifying
program 420 proceeds to step 610 at which a message is displayed
indicating the inability to verify the news item due to an invalid
certificate. The verifying program then terminates a step 612.
[0050] If the certificate is valid verifying program 420 proceeds
to step 614 at which point it determines whether there are further
certificates provided in package 416. This will be the case
according to the second and fourth embodiments of the present
invention. If there are further certificates, the verifying program
proceeds to step 616 at which the certificate at the next level
down in the certificate hierarchy is checked using the public key
obtained from the previous certificate. The verifying program
returns to step 608 to check the validity of the certificate and
the process continues as described above until there are no further
certificates to check and all the certificates have been validated
at which point the verifying program proceeds to step 618.
[0051] At step 618, verifying program 420 decrypts the encrypted
version of the news item provided in the package 416 using public
key 408 obtained from the lowest level certificate, i.e.
certificate 404. At step 620 the verifying program checks whether
the decrypted version of the news item matches the unencrypted
version of the news item. If it does, the verifying program
displays a message at step 622 confirming that the news item has
been verified and also displays shared secret 502 to confirm its
identity to receiving party 500. FIG. 5 shows a web page 710
comprising the news item 702 of FIG. 3 together with confirmation
of verification and shared secret 502 `The cat sat on the mat` 712.
The verifying program then terminates at step 624 of FIG. 4.
[0052] If the news item does not match, the verifying program
displays a message at step 626 indicating that the news item has
been modified and also displays the decrypted version of the news
item. FIG. 6 shows a web page 720 comprising a bogus news item 722
together with a message indicating that the original news item has
been modified 724. FIG. 7 shows a web page 730 comprising the
decrypted version of the news item 702. Verifying program 420 then
terminates at step 624 of FIG. 4.
[0053] In one variant of embodiments of the present invention,
verifying program 420 displays shared secret 502 at step 626 when
displaying a message indicating that the news item has been
modified.
Fifth to Eighth Embodiments
[0054] According to the fifth to eighth embodiments of the present
invention, which are, respectively, variants of the first to fourth
embodiments described above, no unencrypted version of news item
412 is included in package 416.
[0055] In these four embodiments, verification by receiving party
500 is necessary to obtain an unencrypted version news item 412.
Thus, verifying program 420 must be used. Furthermore, verifying
program 420 does not perform a match at step 620, but displays the
decrypted version of the news item together with the shared secret
and then terminates.
Ninth to Twelfth Embodiments
[0056] According to the ninth to twelfth embodiments of the present
invention, which are, respectively, variants of the first to fourth
embodiments described above, news item 412 is not encrypted in
full. Instead, encrypted version 414 is a digital signature which
enables verification but cannot be used to recover the original
news item.
[0057] In these four embodiments, a full unencrypted version of
news item 412 cannot be obtained from encrypted version 414. Thus,
verifying program 420 does not perform a decryption at step 618,
but checks the validity of unencrypted news item 412 using
encrypted version 414. If news item 412 is valid, a message is
displayed confirming that the confirming that the news item is
valid together with shared secret 502. If not, a message is
displayed indicating that the news item has been modified and
verifying program 420 terminates.
[0058] In this document, the term "content" and cognate terms
denote information, data or code of any kind whatsoever which is
transmissible using digital technology. The term "verifying" and
cognate terms denote the process of verifying the identity of a
provider of content or verifying that the content provided has not
been modified since being digitally signed by the content provider.
The term "digitally signing" and cognate terms denote the process
of adapting or adding data to content so that the identity of a
provider of content and the integrity of the content itself can be
verified. The terms "Internet client device" or "client device" and
cognate terms denote a computer or other digital equipment capable
of accessing or receiving content transmitted over a public data
network. The terms "Internet server", "web server", "server" and
cognate terms denote a computer or other digital equipment capable
of transmitting content or making content available for
transmission over a public data network. Further, the term "content
provider" and cognate terms denote a party transmitting content or
making content available for transmission over a public data
network.
[0059] It will be appreciated that the embodiments described above
are not intended to be limiting. Modifications and variants may be
employed without departing from the scope of the present invention,
which is defined in the accompanying claims.
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References