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US5373561A
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Method of extending the validity of a cryptographic certificate
Assignee: Surety LLC
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Filing: 1992-12-21
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Granted: 1994-12-13
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Expires: 2012-12-21
Abstract
Abstract A cryptographic certificate attesting to the authenticity of original document elements, such as time of creation, content, or source, will lose its value when the cryptographic function underlying the certifying scheme is compromised. The present invention provides a means for extending the reliability of such a certificate by subjecting, prior to any such compromise, a combination of the original certificate and the document digital representation from which that certificate was derived to a scheme based on a different and ostensibly less vulnerable function. The new certificate resulting from this procedure extends the validity of the original authenticity by implacably incorporating the original certificate at a time when that certificate could only have been derived by legitimate means.
Inventors
- 👤 Stuart A. Haber
- 👤 Wakefield S. Stornetta, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:25
CPC Classifications
G; G06; G06Q; G06Q20/00; G06Q20/38; G06Q20/382; G06Q20/3821; G06Q20/38215; G06Q20/389; H; H04; H04L; H04L9/00; H04L9/32; H04L9/3263; H04L2209/00; H04L2209/60
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
75 words
A method of extending the validity of a first cryptographic certificate derived by applying a first cryptographic function to a digital document, which method comprises: a) combining a digital representation of said document with a digital representation of said certificate; and b) applying to the resulting combination during the valid term of said first certificate a different cryptographic function to thereby generate a second certificate attesting to the then current validity of said first certificate.
Claim 2
Independent Claim
75 words
A method of extending the validity of a first cryptographic certificate derived by applying a first cryptographic function to a digital document, which method comprises: a) combining a digital representation of said document with a digital representation of said certificate; and b) applying to the resulting combination during the valid term of said first certificate a different cryptographic function to thereby generate a second certificate attesting to the then current validity of said first certificate.
Claim 3
Dependent Claim
15 words
A method according to claim 1 wherein said first function is a cryptographic signature scheme.
Claim 4
Dependent Claim
14 words
A method according to claim 2 wherein said different function is a time-stamping procedure.
Claim 5
Dependent Claim
15 words
A method according to claim 3 wherein said different function comprises a one-way hashing algorithm.
Claim 6
Dependent Claim
14 words
A method according to claim 1 wherein said first function is a time-stamping procedure.
Claim 7
Dependent Claim
15 words
A method according to claim 5 wherein said first function comprises a one-way hashing algorithm.
Claim 8
Dependent Claim
14 words
A method according to claim 5 wherein said different function is a time-stamping procedure.
Claim 9
Dependent Claim
26 words
A method according to claim 7 wherein said first function comprises a first one-way hashing algorithm and said different function comprises a different one-way hashing algorithm.
Claim 10
Dependent Claim
14 words
A method according to claim 1 wherein said different function is a time-stamping procedure.
Claim 11
Independent Claim
61 words
A method of certifying a digital representation of a document which comprises: a) generating a first certificate by applying to said digital representation at least a first cryptographic function; b) combining said first certificate with said digital representation; and c) generating a second certificate by applying to said combination at least one cryptographic function which is different from said first function.
Claim 12
Independent Claim
61 words
A method of certifying a digital representation of a document which comprises: a) generating a first certificate by applying to said digital representation at least a first cryptographic function; b) combining said first certificate with said digital representation; and c) generating a second certificate by applying to said combination at least one cryptographic function which is different from said first function.
Claim 13
Dependent Claim
15 words
A method according to claim 10 wherein said first function is a cryptographic signature scheme.
Claim 14
Dependent Claim
14 words
A method according to claim 11 wherein said different function is a time-stamping procedure.
Claim 15
Dependent Claim
15 words
A method according to claim 12 wherein said different function comprises a one-way hashing algorithm.
Claim 16
Dependent Claim
14 words
A method according to claim 10 wherein said first function is a time-stamping procedure.
Claim 17
Dependent Claim
15 words
A method according to claim 14 wherein said first function comprises a one-way hashing algorithm.
Claim 18
Dependent Claim
14 words
A method according to claim 14 wherein said different function is a time-stamping procedure.
Claim 19
Dependent Claim
26 words
A method according to claim 16 wherein said first function comprises a first one-way hashing algorithm and said different function comprises a different one-way hashing algorithm.
Claim 20
Dependent Claim
53 words
A method according to claim 10 wherein: a) said first certificate is generated by applying to said digital representation at least first and second different cryptographic functions; and b) said second certificate is generated by applying to said combination at least one cryptographic function which is different from said first and second functions.
Claim 21
Dependent Claim
24 words
A certificate authenticating a digital representation of a document, said certificate consisting of a second certificate generated according to the method of claim 10.
Claim 22
Dependent Claim
53 words
A certificate according to claim 19 wherein: a) said first certificate is generated by applying to said digital representation at least first and second different cryptographic functions; and b) said second certificate is generated by applying to said combination at least one cryptographic function which is different from said first and second functions.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-12-12 | 1998-06-13 | 1998-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-12 | 2002-06-13 | 2002-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-12 | 2006-06-13 | 2006-12-13 | $7700.00 | Window Closed / Lapsed |