Commitment scheme: Difference between revisions

Revision as of 10:45, 18 June 2024

Revision as of 00:36, 25 June 2024

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==Construction==

A commitment scheme can either be perfectly binding (it is impossible for Alice to alter her commitment after she has made it, even if she has unbounded computational resources); or perfectly concealing (it is impossible for Bob to find out the commitment without Alice revealing it, even if he has unbounded computational resources); or formulated as an instance-dependent commitment scheme, which is either hiding or binding depending on the solution to another problem.<ref>Shien Hin Ong and Salil Vadhan (1990). Perfect zero knowledge in constant round, In Proc. STOC, p. 482-493482–493, cited in Shien Hin Ong and Salil Vadhan (2008). An Equivalence between Zero Knowledge and Commitments, Theory of Cryptography.</ref><ref>Toshiya Itoh, Yiji Ohta, Hiroki Shizuya (1997). A language dependent cryptographic primitive, In J. Cryptol., 10(1):37-49, cited in Shien Hin Ong and Salil Vadhan (2008). An Equivalence between Zero Knowledge and Commitments, Theory of Cryptography.</ref> A commitment scheme cannot be both perfectly hiding and perfectly binding at the same time.

===Bit-commitment in the random oracle model===