Multi-step digital signature method and system
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Abstract
A multi-step signing system and method uses multiple signing devices to affix a single signature which can be verified using a single public verification key. Each signing device posesses a share of the signature key and affixes a partial signature in response to authorization from a plurality of authorizing agents. In a serial embodiment, after a first partial signature has been affixed, a second signing device exponentiates the first partial signature. In a parallel embodiment, each signing device affixes a partial signature, and the plurality of partial signatures are multiplied together to form the final signature. Security of the system is enhanced by distributing capability to affix signatures among a plurality of signing devices and by distributing authority us affix a partial signature amond a plurality of authorizing agents.
117 Citations
26 Claims
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1-4. -4. (canceled)
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5. A digital signature formed by the steps of:
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generating shares of a private signature key;
storing shares in separate electronic signing devices;
certifying multiple authorizing agents for signing devices; and
for each of a plurality of signing devices, affixing a partial signature to an electronic message in response to authorization from a minimum number of authorizing agents;
wherein a plurality of partial signatures constitutes a digital signature. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A partial digital signature used in a digital signing method, said digital signing method comprising steps of:
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generating shares of a private signature key;
storing shares in separate electronic signing devices;
certifying multiple authorizing agents for signing devices; and
for each of a plurality of signing devices, affixing a partial signature to an electronic message in response to authorization from a minimum number of authorizing agents;
wherein a plurality of partial signatures constitutes a digital signature. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification