Method and apparatus for providing verifiable digital signatures
First Claim
1. A digital signature method, comprising:
- converting, on a computer system, digital data representative of a document into a predetermined format;
applying the predetermined format and a viewer program to a hash function to mathematically operate on the predetermined format and the viewer program and provide a message digest, the viewer program for viewing the predetermined format that is a representation of the document; and
encrypting the message digest using a private key to provide a digital signature.
3 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for providing verifiable digital signatures. In one embodiment, a method includes converting, on a computer system, digital data representative of a document into a predetermined format, and applying the predetermined format and a viewer program to a hash function to mathematically operate on the predetermined format and the viewer program and provide a message digest. The viewer program is used for viewing the predetermined format that is a representation of the document. The method further includes encrypting the message digest using a private key to provide a digital signature. In one embodiment, the predetermined format is a bitmap representation of the document. Moreover, in one embodiment, the method further includes incorporating a file in the digital signature, where the file includes one or more parameters specifying an environment of the computer system at the time of creation of the digital signature. The method and apparatus establishes integrity and trust in digital signatures, providing evidence that the sending and receiving parties are seeing the identical view of the digitally signed document(s).
96 Citations
23 Claims
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1. A digital signature method, comprising:
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converting, on a computer system, digital data representative of a document into a predetermined format;
applying the predetermined format and a viewer program to a hash function to mathematically operate on the predetermined format and the viewer program and provide a message digest, the viewer program for viewing the predetermined format that is a representation of the document; and
encrypting the message digest using a private key to provide a digital signature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system, comprising:
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a network;
a first computer system including a processor and memory including digital data representative of a document and a viewer module, said processor to convert the document into a predetermined format, apply the predetermined format and viewer module to a hash function and provide a message digest, encrypt the message digest with a private key to provide a digital signature, and transmit the predetermined format, viewer module, and digital signature over the network; and
a second computer system including a processor and memory, said processor to receive the predetermined format, viewer module, and digital private key, recover the message digest, apply the predetermined format and viewer module to a corresponding hash function to provide a calculated message digest, compare the calculated message digest with the recovered message digest, and view the predetermined format with the viewer program to provide a representation of the document, if the calculated message digest is identical to the recovered message digest. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method, comprising:
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converting, on a computer system, a document into a predetermined format;
appending the predetermined format with a viewer program to provide a file archive, the viewer program for viewing the predetermined format that is a representation of the document;
applying the file archive to a hash function to mathematically operate on the file archive and provide a message digest; and
encrypting the message digest using a private key to provide a digital signature. - View Dependent Claims (19, 20, 21, 22, 23)
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Specification