05136643 is referenced by 207 patents and cites 14 patents.

A time notarization apparatus and method is disclosed which uses a secure, microprocessor based hardware platform which performs public key crytographic operations to obtain trusted time stamping with a minimum of intervention by third parties. The hardware platform is encapsulated in a secure fashion so that the device's timestamping mechanism may not be readily tampered with or altered. The hardware platform includes at least one digital clock and a stable, secure storage device to record the private half of a public/private key pair. Coupled to both the digital clock and the storage device is a data processing device which performs public key signature operations in a secure and tamper-proof manner. Only the processing device has access to the secure storage device and its associated private key. The hardware platform also includes input/output means which receives a digital message which is to be digitally signed and timestamped and which outputs the resulting timestamped signature generated by the device. The hardware platform also includes a power source, (e.g., on on-board battery) to ensure the accuracy of the device's digital clock and the security of storage data prior to installation or in case of a power failure.

Title
Public/key date-time notary facility
Application Number
421104
Publication Number
5136643
Application Date
December 20, 1990
Publication Date
August 4, 1992
Inventor
Addison M Fischer
60 14th Ave. South, Naples, 33942
FL, US
Agent
Nixon & Vanderhye
IPC
H04K 1/00
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