Method for secure time-stamping of digital documents
US5136647A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 1990 |
| Grant date | Aug 4, 1992 |
| Priority date | — |
| Expiry date | Aug 2, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/60
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A system for time-stamping a digital document, including for example text, video, audio, or pictorial data, protects the secrecy of the document text and provides a tamper-proof time seal establishing an author's claim to the temporal existence of the document. Initially, the author reduces the document to a number by means of a one-way hash function, thereby fixing a unique representation of the document text. In one embodiment of the invention the number is then transmitted to an outside agency where the current time is added to form a receipt which is certified by the agency using a public key signature procedure before being returned to the author as evidence of the document's existence. In later proof of such existence, the certificate is authenticated by means of the agency's public key to reveal the receipt which comprises the hash of the alleged document along with the time seal that only the agency could have signed into the certificate. The alleged document is then hashed with the same one-way function and the original and newly-generated hash numbers are compared. A match establishes the identify of the alleged document as the time-stamped original. In order to prevent c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.