05373561 is referenced by 209 patents and cites 8 patents.

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.

Title
Method of extending the validity of a cryptographic certificate
Application Number
7/992883
Publication Number
5373561
Application Date
December 21, 1992
Publication Date
December 13, 1994
Inventor
Wakefield S Stornetta Jr
Morristown
NJ, US
Stuart A Haber
New York
NY, US
Agent
Lionel N White
Leonard Charles Suchyta
Assignee
Bell Communications Research
NJ, US
IPC
H04L 9/30
H04L 9/00
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