Digital signing method
First Claim
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1. A digital signing method, comprising:
- providing a log list comprising previously generated digital signatures;
computing a hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only the most recently generated digital signature obtained from the log list or a hash value thereof;
encoding the computed hash value of the inputted data to produce encoded data of a predetermined format that is suitable for encryption processing for generating a signature;
applying a secret key to the encoded data to produce a generated digital signature;
registering as log data the generated digital signature in the log list; and
distributing a signature-attached data including the generated digital signature, the message to be signed, and the earlier generated digital signature or the hash value thereof.
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Abstract
According to the invention, techniques for authenticating that a digitally signed document is genuine. Specific embodiments according to the present invention can determine whether a digital signature was generated by a digital signature generator, or if the digital signature was generated by a third party posing as the digital signature generator. Specific embodiments can provide independent verification of digital signer identity based upon prior signed messages, time/date stamps, and the like. Techniques according to the present invention can be embodied in methods, apparatus, computer software and systems.
39 Citations
14 Claims
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1. A digital signing method, comprising:
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providing a log list comprising previously generated digital signatures; computing a hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only the most recently generated digital signature obtained from the log list or a hash value thereof; encoding the computed hash value of the inputted data to produce encoded data of a predetermined format that is suitable for encryption processing for generating a signature; applying a secret key to the encoded data to produce a generated digital signature; registering as log data the generated digital signature in the log list; and distributing a signature-attached data including the generated digital signature, the message to be signed, and the earlier generated digital signature or the hash value thereof. - View Dependent Claims (2, 3, 4)
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5. A digital signing apparatus, comprising:
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a processor; and a storage medium to store a log list comprising previously generated digital signatures, wherein said processor computes a hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only the most recently generated digital signature obtained from the log list or a hash value thereof, and wherein said processor encodes the computed hash value of the inputted data into encoded data of a predetermined format that is suitable for encryption processing for generating a signature; said processor applies a secret key to the encoded data to produce a generated digital signature; said processor prepares a signature-attached data including the generated digital signature for the message to be signed, the message to be signed, and the previous log data or the hash value thereof for generating the signature; and said processor registers as log data the signature-attached data in the log list. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A computer-readable storage medium for creating a digital signature, the computer-readable storage medium comprising:
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program code to maintain a log list comprising previously generated digital signatures; program code to operate a processor to compute a hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only the most recently generated digital signature obtained from the log list or a hash value thereof; program code to operate the processor to encode the computed hash value of the inputted data into predetermined format data that is suitable for encryption processing for generating a signature; program code to operate the processor to apply a secret key to the encoded data to produce a generated digital signature; and program code to operate the processor to register as log data the generated digital signature in the log list. - View Dependent Claims (13, 14)
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Specification