Electronic document processing system and method of forming digital signature
Patent 5465299 Issued on November 7, 1995. Estimated Expiration Date: 
November 29, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
November 29, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesElectronic transaction system Fully integrated telecommunication network Patent #: 5018195 InventorsAssigneeApplicationNo. 158618 filed on 11/29/1993US Classes:713/176, Authentication by digital signature representation or digital watermark380/30, Public key705/80, ELECTRONIC NEGOTIATION713/177Signature treeExaminersPrimary: Cain, DavidAttorney, Agent or FirmInternational ClassH04K 001/00Foreign Application Priority Data1992-12-03 JPAbstractIn a terminal which received an electronic document with at leastone digital signature, when a user changes the contents of the received electronic document, a new digital signature is produced by enciphering signature data by using a secret key of the user, the signature data including a hash total of the document of a new version, personal information of the user (signatory), and version management information necessary to restore an electronic document of a former version from the electronic document of the new version. The new digital signature and the new version electronic document version are transmitted together with the received digital signature to a next person on a document circulating route.Other References
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