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A randomized protocol for signing contracts (1990)
| Citations: | 594 - 11 self |
BibTeX
@MISC{Ben-Or90arandomized,
author = {Michael Ben-Or and Oded Goldreich and Silvio Micali and Ronald L. Rivest},
title = {A randomized protocol for signing contracts},
year = {1990}
}
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Abstract
Two parties, A and B, want to sign a contract C over a communication network. To do so, they must “simultaneously” exchange their commitments to C. Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchanging partial commitments in piece by piece manner. During such a protocol, one party or another may have a slight advantage; a “fair” protocol keeps this advantage within acceptable limits. We present a new protocol that is fair in the sense that, at any stage in its execution, the conditional probability that one party cannot commit both parties to the contract given that the other party can, is close to zero. This is true even if A and B have vastly different computing powers, and is proved under very weak cryptographic assumptions. Our protocol has the following additional properties: 4 during the procedure the parties exchange probadilistic options for committing both parties to the contract; the protocol never terminates in an asymmetric situation where party A knows that party B is committed to the contract while he is not; the protocol makes use of a weak form of a third party (judge). If both A and B are honest, the judge will never be called upon. Otherwise, the judge rules by performing a simple computation. No bookkeeping is required of the judge.
Keyphrases
acceptable limit fair protocol simple computation asymmetric situation communication network new protocol abtract-two party simultaneous exchange following additional property slight advantage weak form partial commitment party cannot judge rule third party conditional probability weak cryptographic assumption piece manner probadilistic option
