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 possesses 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 among a plurality of authorizing agents.

Abstract: A method of distributed cryptography for high consequence security systems which employs shared randomness between operating parties. Shared randomness is accomplished by sharing cryptographic keys stored in secure hardware tokens by potentially less secure software or general purpose computing units that perform distributed cryptography. The shared randomness is based on shared keys (at the tokens) and unique context. Shared random values are incorporated into the computation of partial results used in the distributed cryptographic calculation. The incorporation of shared randomness provides a hand-shake among the hardware tokens. When the operation is successful, a result is computed with assurance that the correct parties have taken part in forming the result. The hand-shake assures binding of operating parties and added system security.

Abstract: A method of distributed cryptography for high consequence security systems which employs shared randomness between operating parties. Shared randomness is accomplished by sharing cryptographic keys stored in secure hardware tokens by potentially less secure software or general purpose computing units that perform distributed cryptography. The shared randomness is based on shared keys (at the tokens) and unique context. Shared random values are incorporated into the computation of partial results used in the distributed cryptographic calculation. The incorporation of shared randomness provides a hand-shake among the hardware tokens. When the operation is successful, a result is computed with assurance that the correct parties have taken part in forming the result. The hand-shake assures binding of operating parties and added system security.