Transmitting revisions with digital signatures
First Claim
1. A computer network, comprising:
- a first computer system providing access to a user, including;
means for providing a first digital-document;
signing means for deriving a first digital-fingerprint from the first digital-document document, the first digital-fingerprint being a smaller different and separate or separable digital-document from the first digital-document; and
first transmitting means for transmitting the first digital-fingerprint;
a second computer system that is secure from direct access by the user, including;
first receiving means for receiving the first digital-fingerprint from the first system;
timestamping means for producing a first digital-timestamp and containing a first digital-time of the first digital-timestamp and the first digital-fingerprint; and
second transmitting means for transmitting the first digital-timestamp to the first system;
the first system further comprises;
second receiving means for receiving the first digital-timestamp from the second computer system;
first storing means for storing the first digital-timestamp; and
means for revising the first digital-document to produce a second digital-document independent of the first digital-timestamp;
and wherein;
the signing means derive a second digital-fingerprint from both the second digital-document and an indicator of the first digital-document to provide evidence that the second digital-document is a revision of the first digital-document, the indicator including at least a portion of the first digital-timestamp;
the first transmitting means transmit the second digital-fingerprint to the second computer system, the second computer system being secure from access by users who produce the second digital-document, or who initiate deriving the second digital-fingerprint or who initiate transmitting the second-digital-fingerprint;
the first receiving means of the second system receives the second digital-fingerprint from the first system;
the timestamping means produces a second digital-timestamp containing a second digital-time of the second timestamp and the second digital-fingerprint;
the second transmitting means transmits the second digital-fingerprint to the first system;
the second receiving means of the first system receives the second-timestamp from the first system; and
the storing means stores the second digital-timestamp;
the computer network further comprising;
means for authenticating digital-timestamps, the authenticating including determining whether the digital-timestamps were produced on the second system and whether the digital-timestamps have been altered since they were produced;
means for authenticating digital-documents depending on authenticating the digital-timestamp for the digital-document and from the second digital-fingerprint contained in the second digital-timestamp; and
means for verifying that the second digital-document is a revision of the first digital-document depending on the portion of the first digital-timestamp from which the second digital-fingerprint was derived.
1 Assignment
0 Petitions
Accused Products
Abstract
In a computer network, documents are produced, the document is hashed to produce a fingerprint, and the fingerprint is encrypted to sign the document then the document signature is transmitted from the user system to a secure computer system. The secure computer system creates a time stamp including the document signature and a digital time. The secure system signs the time stamp to verify its origin. The time stamp and notary'"'"'s signature are transmitted from the secure system to the user'"'"'s system. The user has access to the notary'"'"'s public key which is used for determining whether the time stamp is authentic. Then, if the document is revised, the revised document is hashed and the hash is combined with an indication that the revision is related to the original document. The indication could be a hash of the original document, the original document signature, the notary'"'"'s time stamp for the original document, or the notary'"'"'s signature for the original document.
170 Citations
58 Claims
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1. A computer network, comprising:
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a first computer system providing access to a user, including;
means for providing a first digital-document;
signing means for deriving a first digital-fingerprint from the first digital-document document, the first digital-fingerprint being a smaller different and separate or separable digital-document from the first digital-document; and
first transmitting means for transmitting the first digital-fingerprint;
a second computer system that is secure from direct access by the user, including;
first receiving means for receiving the first digital-fingerprint from the first system;
timestamping means for producing a first digital-timestamp and containing a first digital-time of the first digital-timestamp and the first digital-fingerprint; and
second transmitting means for transmitting the first digital-timestamp to the first system;
the first system further comprises;
second receiving means for receiving the first digital-timestamp from the second computer system;
first storing means for storing the first digital-timestamp; and
means for revising the first digital-document to produce a second digital-document independent of the first digital-timestamp;
and wherein;
the signing means derive a second digital-fingerprint from both the second digital-document and an indicator of the first digital-document to provide evidence that the second digital-document is a revision of the first digital-document, the indicator including at least a portion of the first digital-timestamp;
the first transmitting means transmit the second digital-fingerprint to the second computer system, the second computer system being secure from access by users who produce the second digital-document, or who initiate deriving the second digital-fingerprint or who initiate transmitting the second-digital-fingerprint;
the first receiving means of the second system receives the second digital-fingerprint from the first system;
the timestamping means produces a second digital-timestamp containing a second digital-time of the second timestamp and the second digital-fingerprint;
the second transmitting means transmits the second digital-fingerprint to the first system;
the second receiving means of the first system receives the second-timestamp from the first system; and
the storing means stores the second digital-timestamp;
the computer network further comprising;
means for authenticating digital-timestamps, the authenticating including determining whether the digital-timestamps were produced on the second system and whether the digital-timestamps have been altered since they were produced;
means for authenticating digital-documents depending on authenticating the digital-timestamp for the digital-document and from the second digital-fingerprint contained in the second digital-timestamp; and
means for verifying that the second digital-document is a revision of the first digital-document depending on the portion of the first digital-timestamp from which the second digital-fingerprint was derived. - View Dependent Claims (2, 3)
means for authenticating digital-documents depending on authenticating the digital-timestamp for the digital-document and from the second digital-fingerprint contained in the second digital-timestamp; and
means for verifying that the second digital-document is a revision of the first digital-document depending on the portion of the first digital-timestamp from which the second digital-fingerprint was derived;
and in which the authenticating means includes;
a private-key for encrypting data in the second system the private-key being secure from access by the user;
a public-key in the first system for decrypting the encrypted data that was previously encrypted using the private-key;
second signing means for producing respective digital-signatures from the digital-timestamps by encryption using the private-key in the second system;
means for decrypting the digital-signatures for the digital-timestamps using the public-key to re-produce the respective digital-timestamps on the first system; and
means for comparing the respective transmitted digital-timestamps and re-produced digital-timestamps on the first system to determine whether the digital-timestamps are authentic;
and in which;
the second transmitting means transmit the digital-signatures for the digital-timestamps to the first system; and
the second receiving means receives the digital-signatures for the digital-timestamps in the first system.
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3. The network of claim 1, further comprising:
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means for authenticating digital-documents depending on authenticating the digital-timestamp for the digital-document and from the second digital-fingerprint contained in the second digital-timestamp; and
means for verifying that the second digital-document is a revision of the first digital-document depending on the portion of the first digital-timestamp from which the second digital-fingerprint was derived;
and in which the authenticating means include;
second storing means for storing the digital-timestamps on the second system the second storing means being secure from direct access by the user;
means to retrieve the digital-timestamp from second storage into the second system;
means to compare the retrieved digital-timestamp and transmitted digital-timestamp, in the second system; and
means to transmit an authentication signal or authentication failure signal from the second system to the first system, depending on the comparison;
and in which the first transmitting means transmit the digital-timestamps from the first system to the second system.
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4. A method of operating a computer network, comprising the steps of:
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providing a first digital-document on a first computer system access to a user;
deriving a first digital-fingerprint from the first digital-document on the first system;
transmitting the first digital-fingerprint from the first system to a second computer system that is secure from direct access by the user;
creating a first digital-timestamp including the first digital-fingerprint and a first digital-time;
transmitting the first digital-timestamp from the second system to the first system;
revising the first digital-document to produce a second digital-document;
deriving a second digital-fingerprint from the second digital-document and from an indicator of the first digital-document to provide evidence that the second digital-document is a revision of the first digital-document, the indicator including at least a portion of the first digital-timestamp;
transmitting the second digital-fingerprint from the first system to the second system;
creating a second digital-timestamp including the second digital-fingerprint and a second digital-time;
transmitting the second digital-timestamp from the second system to the first system. - View Dependent Claims (5, 6, 7, 8, 9)
determining whether the second digital-timestamp is authentic including determining whether the digital-timestamp was produced on the second system and determining whether the digital-timestamp has been altered since it was produced; and
determining whether the second digital-document is authentic depending on the determination of authenticity of the second digital-timestamp and depending on the second digital-fingerprint contained in the first digital-timestamp;
and in which the step of determining whether the second digital-timestamp is authentic, includes the steps of;
storing the second digital-timestamp in a second storage of the second system, the second storage being secure from direct access by the user;
transmitting the second digital-timestamp between the first system and the second system;
retrieving the second digital-timestamp from the second storage;
comparing the second digital-timestamp that was transmitted with the digital-timestamp that was retrieved from on the second storage; and
determining whether the digital-timestamp is authentic depending on the comparison.
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6. The method of claim 4, further comprising:
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determining whether the second digital-timestamp is authentic including determining whether the digital-timestamp was produced on the second system and determining whether the digital-timestamp has been altered since it was produced; and
determining whether the second digital-document is authentic depending on the determination of authenticity of the second digital-timestamp and depending on the second digital-fingerprint contained in the first digital-timestamp;
and in which, the step of determining whether the second digital-timestamp is authentic, includes the steps of;
providing a private-key on the second system;
encrypting the second digital-timestamp on the second system to produce a third digital-signature;
re-transmitting the digital-timestamp from the first system to the second system;
re-encrypting the digital-timestamp using the private-key on the second system to produce a fourth digital-signature;
comparing the third digital-signature with the fourth digital-signature; and
determining whether the digital-timestamp is authentic depending on the comparison.
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7. The method of claim 4, further comprising:
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determining whether the second digital-timestamp is authentic including determining whether the digital-timestamp was produced on the second system and determining whether the digital-timestamp has been altered since it was produced; and
determining whether the second digital-document is authentic depending on the determination of authenticity of the second digital-timestamp and depending on the second digital-fingerprint contained in the first digital-timestamp;
and in which, the step of determining whether the second digital-timestamp is authentic, includes the steps of;
providing a public digital-key/private digital-key pair, the private digital-key being provided only on the second system and the public digital-key being provided on the first system;
encrypting the second digital-timestamp to produce a second digital-signature using the private-key on the second system;
transmitting the third digital-signature from the second system to the first system;
decrypting the third digital-signature using the public-key to produce a third digital-timestamp;
comparing the second digital-timestamp with the third digital-timestamp;
determining whether the second digital-timestamp is authentic depending on the comparison.
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8. The method of claim 4, further comprising:
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determining whether the second digital-timestamp is authentic including determining whether the digital-timestamp was produced on the second system and determining whether the digital-timestamp has been altered since it was produced; and
determining whether the second digital-document is authentic depending on the determination of authenticity of the second digital-timestamp and depending on the second digital-fingerprint contained in the first digital-timestamp;
and wherein the second digital-fingerprint is derived by the steps of;
hashing the second digital-document using a one-way hash algorithm; and
encrypting the combination to produce a second digital-signature; and
determining whether the second digital-document is authentic includes the steps of;
hashing the second digital-document using the one-way hash algorithm and combining with the indicator of the first digital-document to produce a third digital-fingerprint;
decrypting the second digital-signature contained in the authenticated digital-timestamp to produce a fourth digital-fingerprint;
comparing the third digital-fingerprint with the fourth digital-fingerprint to determine whether the second digital-document is authentic.
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9. The method of claim 4 in which the step of determining whether the second digital-timestamp is authentic, includes the steps of:
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providing a private-key on the second system;
encrypting the second digital-timestamp on the second system to produce a third digital-signature;
storing the third digital-signature in a second storage of the second system the storage being secure from direct access by the user;
transmitting the second digital-timestamp between the first system and the second system;
retrieving the third digital-signature from the second storage;
decrypting the third digital-signature and comparing the result to the second digital-timestamp or encrypting the second digital-timestamp and comparing the result to the third digital-signature; and
determining whether the digital-timestamp is authentic depending on the comparing.
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10. A method for producing signed digital-revisions of digital-documents, comprising:
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providing a first digital-document;
revising the first digital-document to produce a digital-revision, the digital-revision being a second digital-document separate or separable from the first digital-fingerprint;
deriving a second digital-fingerprint from both the first digital-document and the digital-revision;
and in which the digital-fingerprint is a digital-document separate or separable from the digital-documents from which the digital-fingerprint was derived, is smaller than the digital-documents from which the digital-fingerprint was derived, and provides evidence that the digital-documents from which the digital-fingerprint was derived;
are the digital-documents from which the digital-fingerprint was derived; and
have not been altered since the digital-fingerprint was derived. - View Dependent Claims (11, 12, 13, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
the method further comprises the step of providing digital-times for the digital-documents; and
the digital-fingerprint is also derived from the digital-times such that the digital-fingerprint provides evidence that both the digital-documents and the digital-times are associated and have not been altered since the digital-fingerprint was produced.
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17. The method of claim 10 further comprising the steps of:
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deriving a first digital-fingerprint for the first digital-document;
providing a first digital-time for the first digital-document; and
deriving a third digital-fingerprint from both the first digital-fingerprint and the digital-time such that the third digital-fingerprint provides evidence that both the first digital-fingerprint and the first digital-time have not been altered since the third digital-fingerprint was produced.
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18. The method of claim 17 in which the second digital-fingerprint is derived from the third digital-fingerprint such that the second digital-fingerprint is derived from the digital-time and the first digital-fingerprint, and thus from the first digital-document.
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19. The method of claim 10 further comprising the steps of:
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providing a first digital-time for the first digital-document; and
deriving a first digital-timestamp from both the digital-time and the first digital-document, the digital-timestamp being a separate digital-document indicating a relationship between the digital-time and the first digital-document.
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20. The method of claim 19 in which:
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the method further comprises deriving a first digital-fingerprint for the first digital-document; and
the first digital-time and the first digital-fingerprint are appended together into a separate digital-document to form the first digital-timestamp that is thus, derived from the first digital-document.
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21. The method of claim 20 in which the second digital-fingerprint is derived from both the first digital-revision and the digital-timestamp and thus from both the digital-time and the first digital-fingerprint contained in the digital-timestamp and thus from the first digital-document.
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22. The method of claim 20 further comprising the step of:
deriving a third digital-fingerprint from the first digital-timestamp such that the third digital-fingerprint is derived from both the first digital-time and the first digital-fingerprint contained in the digital-timestamp.
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23. The method of claim 22 in which the second digital-fingerprint is derived from both the digital-revision and the third digital-fingerprint and thus from the digital-time and the first digital-fingerprint contained in the first digital-timestamp and thus from the first digital-document.
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24. The method of claim 19 in which:
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the first digital-timestamp is produced in a secure portion of the system to which a user does not have direct access though said user has access to another portion of the system to derive the first digital-fingerprint from the first digital-document;
the method further comprises the steps of;
transmitting the first digital-fingerprint from the user accessible portion to the secure portion of the system; and
receiving the first digital-timestamp in the user accessible portion from the secure portion of the system.
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25. The method of claim 22 in which:
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the first digital-timestamp and third digital-fingerprints are derived in a second secure portion of the system to which a user does not have direct access though said user has access to a first portion of the system to derive the first digital-fingerprint from the first digital-document so that the user cannot control deriving the first digital-timestamp and third digital-fingerprint;
the method further comprises the steps of;
transmitting the first digital-fingerprint from the first portion to the second portion of the system; and
receiving the digital-timestamp and/or the third digital-fingerprint in the first portion from the second portion into the first portion of the system.
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26. The method of claim 10 in which:
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the method further comprises the step of providing a digital-time for the digital-revision; and
the second digital-fingerprint is derived from the first digital-document, the digital-revision and the second digital-time.
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27. The method of claim 10 further comprising the steps of:
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providing a digital-time for the digital-revision; and
deriving a fourth digital-fingerprint derived from both the second digital-fingerprint and the digital-time.
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28. The method of claim 10 further comprising the steps of:
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providing a second digital-time for the digital-revision; and
combining the second digital-fingerprint with the second digital-time to produce a second digital-timestamp.
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14. A method for producing signed digital-revisions of digital-documents, comprising:
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providing a first digital-document;
revising the first digital-document to produce a digital-revision, the digital-revision being a second digital-document separate or separable from the first digital-fingerprint;
deriving a second digital-fingerprint from both the first digital-document and the digital-revision;
in which the digital-fingerprint is a digital-document separate or separable from the digital-documents from which the digital-fingerprint was derived, is smaller than the digital-documents from which the digital-fingerprint was derived, and provides evidence that the digital-documents from which the digital-fingerprint was derived;
are the digital-documents from which the digital-fingerprint was derived; and
have not been altered since the digital-fingerprint was derived; and
in which the digital-fingerprint is a digital-signature derived by applying a private digital-key such that without using the private digital-key, an associated public digital-key can be applied to the digital-signature to provide evidence both that the associated private digital-key was used to produce the digital-signature and that the digital-document from which the digital-signature was derived has not been altered since the digital-signature was produced. - View Dependent Claims (15)
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29. A method for producing digitally-timestamped digital-revisions of digital-documents, comprising:
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providing a first digital-document;
providing a first digital-time for the first digital-document;
producing a first digital-timestamp derived from both the first digital-document and from the first digital-time to provide evidence that the first digital-time is related to the first digital-document;
revising the first digital-document to produce a digital-revision which is a second digital-document;
providing a second digital-time for the digital-revision;
producing a second digital-timestamp derived from the digital-revision, the second digital-time, and an indicator of the first digital-document to provide evidence that digital-time corresponds to the digital-revision and that the digital-revision corresponds to the first digital-document, the indicator being derived from the first digital-document or from at least a portion of the first digital-timestamp;
wherein the first and second digital-timestamps are digital-documents independent from and separate or separable from the first and second digital-documents respectively. - View Dependent Claims (30, 31, 32)
producing the first digital-timestamp includes;
deriving a first digital-fingerprint from the first digital-document; and
combining the first digital-fingerprint with the first digital-time to form the first digital-timestamp; and
producing the second digital-timestamp includes;
deriving a second digital-fingerprint from the digital-revision; and
combining the second digital-fingerprint, the second digital-time, and the indicator of the first digital-document to form the second digital-timestamp.
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31. The method of claim 30 in which:
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the method further comprises deriving a third digital-fingerprint from the first digital-timestamp; and
the indicator of the first digital-document includes the third digital-fingerprint.
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32. The method of claim 30 in which the indicator of the first digital-document includes or is derived from at least one of the following specific indicators:
- the digital-fingerprint of the first digital-document;
the digital-time for the first digital-document; and
a digital-sequence-number, digital-name, or another indicator of the original document added to the first digital-timestamp by a portion of the system that is secure from access by a user.
- the digital-fingerprint of the first digital-document;
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33. A digital-fingerprint derived from a digital-revision of a first digital-document and on an indicator of the first digital-document that is not contained in the digital-revision so as to provide evidence that the digital-revision is derived from the first digital-document and that the digital-revision has not be altered since the digital-fingerprint was produced.
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34. A digital-timestamp comprising:
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a digital-fingerprint derived from a digital-revision of a first digital-document, the digital-revision being a second digital-document, the digital-timestamp being separate or separable from the digital-revision and from the first digital-document;
a digital-time for the digital-revision indicating the existence of the digital-revision at a time before the digital-time; and
means to indicate the first digital-document for providing evidence that the digital-revision is a revision of the first digital-document.
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35. A computer system, comprising:
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means for providing a first digital-document;
means for deriving a first digital-fingerprint from the first digital-document;
means for revising the first digital-document to produce a digital-revision which is a second digital-document, the digital-revision being a second digital-document that is separate or separable from the first digital-document and means for deriving a second digital-fingerprint from both the first digital-fingerprint and the digital-revision;
and in which each digital-fingerprint is a digital-document that is;
independent and separate or separable from the digital-document or digital-documents on which it depends; and
provides evidence that the digital-document or digital-documents from which the digital-fingerprint was derived;
is the digital-document or digital-documents from which the digital-fingerprint was derived; and
has not been altered since the digital-fingerprint was produced. - View Dependent Claims (36, 37, 38)
the respective means for deriving the first and second digital-fingerprints use the same one-way-hash algorithm to produce respective hashes which are smaller different separate or separable digital-documents than the digital-documents upon which the digital-fingerprints were derived;
each digital-fingerprint is a respective digital-signature produced by applying a private digital-key to the respective hash such that without using the private digital-key, an associated public digital-key can be applied to the digital-signature to provide evidence both that the associated private digital-key was used to produce the digital-signature and that the digital-document on which the digital-signature is based has not been altered since the digital-signature was produced.
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37. The system of claim 35 in which:
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the system further comprises means for providing different first and second digital-times respectively for the first and second digital-documents indicating a time before which the first and second digital-documents respectively, existed; and
the means for deriving the first and second digital-fingerprints, derive the digital-fingerprints from the first and second digital-times respectively such that the digital-fingerprints also provide evidence that the associated digital-times have not been altered since the digital-fingerprints were produced.
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38. The system of claim 37 in which the means for deriving the second digital-fingerprints, derive the second digital-fingerprints, from the digital-time associated with the first digital-document.
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39. A computer system, comprising:
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means for providing a first digital-document;
means for deriving a first digital-fingerprint from the first digital-document, the first digital-fingerprint indicating that the first digital-fingerprint is for the first digital-document and that the first digital-document has not been altered since the first digital-fingerprint was produced;
means to produce a first digital-time for the first digital-document for indicating a time before which the first digital-fingerprint existed;
means for deriving first digital-timestamp from both the first digital-fingerprint and first digital-time to indicate that the first digital-time is for the first digital-fingerprint and thus, for the first digital-document, the digital-timestamp being a separate or separable digital-document;
means for revising the first digital-document to produce a digital-revision, the digital-revision being a second digital-document;
means for deriving a second digital-fingerprint depending on the digital-revision, the second digital-fingerprint indicating that the second digital-fingerprint is for the digital-revision and that the digital-revision has not been altered since the second digital-fingerprint was produced;
means to produce a second digital-time for the digital-revision for indicating a digital-time at which the second digital-time was created and at which the second digital-fingerprint existed and thus a time after the digital-revision began existing;
means for deriving a second digital-timestamp from the second digital-fingerprint, the second digital-time, and an indication of the first digital-document which indicates to provide evidence that the second digital-time is for the second digital-fingerprint and thus for the digital-revision, and that the digital-revision is a revision of the first digital-document, the second digital-timestamp being a separate digital-document;
and in which each digital-fingerprint is a digital-document separate or separable from the digital-document on which the digital-fingerprint depends and is smaller than the digital-document on which the digital-fingerprint depends. - View Dependent Claims (40, 41, 42)
the system further comprises means for deriving a third digital-fingerprint from the first digital-timestamp; and
the second digital-timestamp is derived from the third digital-fingerprint as the indication that the second digital-document is a revision of the first digital-document.
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43. A method of operating a computer network, comprising the steps of:
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providing a first digital-document on a first computer system with user access;
deriving a first digital-signature from the first digital-document on the first system;
transmitting the first digital-signature from the first system to a second computer system that is secure from direct user access;
creating a first digital-timestamp derived from the first digital-signature and a first digital-time;
transmitting the first digital-timestamp from the second system to the first system;
revising the first digital-document to produce a second digital-document;
deriving a second digital-signature from the second digital-document;
transmitting the second digital-signature and an indicator of the first digital-document from the first system to the second system, the indicator providing evidence that the second digital-document is being dependent on at least one of;
the first digital-signature and the first digital-time;
creating a second digital-timestamp derived from the second digital-signature, the indicator of the first digital-document, and a second digital-time;
transmitting the second digital-timestamp from the second system to the first system;
determining whether the second digital-timestamp is authentic;
determining whether the second digital-document is authentic depending on the determination of authenticity of the second digital-timestamp and depending on the second digital-fingerprint from which the second digital-timestamp was derived. - View Dependent Claims (44, 45)
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46. A computer system, comprising:
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means for providing a digital-revision which is a digital- document that is a revision of an original digital-document;
cryptographic means for providing an indicator for the original digital-document that can be used to identify the original digital-document and which is not contained in the digital-revision, said indicator providing evidence that the original digital-document has not been revised;
means for providing a private-key for encrypting digital-documents and public-keys for decrypting documents encrypted by the private-key;
means for encrypting the digital-revision or a fingerprint document derived from the digital-revision together with the indication of the original document using a private-key of the signor to form a digital-signature for the digital-revision, the digital-signature providing evidence that;
the digital-signature was produced by the private-key;
the digital-revision has not been changed since the digital-signature was produced; and
the digital-revision is derived from the original digital-document.
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47. A digital-signature derived from a digital-revision which is a digital-document that is a revision of an original digital-document, the digital-signature being derived by encrypting the digital-revision or a fingerprint of the digital-revision, the encryption using a private-key of a signor, the digital-signature comprising:
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means for indicating that the signature was produced using the private-key of the signor;
means for indicating that the revised digital-document has not been modified since the signature was produced; and
means for indicating that the revised digital-document is derived from the original document, the means for indicating not being contained in the revised digital-document.
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48. A method for producing digitally-timestamped digital-revisions of digital-documents, comprising:
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means for providing a first digital-document;
means for providing a first digital-time for the first digital-document;
means for producing a first digital-timestamp derived from both the first digital-document and from the first digital-time to provide evidence that the first digital-time is related to the first digital-document;
means for revising the first digital-document to produce a digital-revision which is a second digital-document;
means for providing a second digital-time for the digital-revision; and
means for producing a second digital-timestamp derived from the digital-revision, the second digital-time and an indicator of the first digital-document to provide evidence that the second digital-time is related to the digital-revision and that the digital-revision is a revision of the first digital-document, the indicator being derived from the first digital-document or from at least a portion of the first digital-timestamp;
and wherein the first and second digital-timestamps are digital-documents independent and separate or separable from the first and second digital-documents respectively.
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49. A method, comprising:
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providing a first digital-document;
revising the first digital-document to produce a second digital-document;
deriving a second digital-fingerprint from both a second indicator of the second digital-document and a first indicator of the first digital-document, which first indicator can not be derived from the second digital-document. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58)
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Specification