Cryptology ePrint Archive: Report 1999/016

A forward-secure digital signature scheme

Mihir Bellare and Sara Miner

Abstract: We describe a digital signature scheme in which the public key is fixed but the secret signing key is updated at regular intervals so as to provide a <i>forward security</i> property: compromise of the current secret key does not enable an adversary to forge signatures pertaining to the past. This can be useful to mitigate the damage caused by key exposure without requiring distribution of keys. Our construction uses ideas from the Fiat-Shamir and Ong-Schnorr identification and signature schemes, and is proven to be forward secure based on the hardness of factoring, in the random oracle model. The construction is also quite efficient.

Category / Keywords: Digital signatures, forward security, identification, factoring.

Publication Info: Appeared in the THEORY OF CRYPTOGRAPHY LIBRARY and has been included in the ePrint Archive.

Date: received July 13th, 1999.

Contact author: mihir at cs ucsd edu

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