| 摘要 |
The certification of electronic documents for subsequent verification and authentication is disclosed. Pursuant to a request to certify a document, a digital signature is extracted from the document. The digital signature corresponds to the content of the document and is unique to the document. Thus, signatures extracted from documents that are even slightly different from the certified document, or from a document that has been changed, will be different. A certification provider maintains the digital certification signature, an identification code such as a serial number, and other information such as the time and date of certification. The serial number is returned to the certification requester. When verification is sought, the serial number and the document alleged to have been certified are given to the certification provider. The serial number is used to index the previously extracted digital certification signature. The same extraction process is used to extract a signature from the document alleged to have been certified. Then the digital signatures are compared. A match indicates that the alleged document and the previously certified one are the same, and a mismatch indicates the opposite. The certification can be used to provide an electronic timestamp for a document, thus providing proof of possession of the document at the time of certification. It can also be used in conjunction with an electronic mail transmission to a third party recipient, thus providing certified electronic mail.
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