Date: 08 Feb 2002

Homomorphic Signature Schemes

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Abstract

Privacy homomorphisms, encryption schemes that are also homomorphisms relative to some binary operation, have been studied for some time, but one may also consider the analogous problem of homomorphic signature schemes. In this paper we introduce basic definitions of security for homomorphic signature systems, motivate the inquiry with example applications, and describe several schemes that are homomorphic with respect to useful binary operations. In particular, we describe a scheme that allows a signature holder to construct the signature on an arbitrarily redacted submessage of the originally signed message. We present another scheme for signing sets that is homomorphic with respect to both union and taking subsets. Finally, we show that any signature scheme that is homomorphic with respect to integer addition must be insecure.

This research was supported in part by the Defense Advanced Research Projects Agency under DARPA contract N6601-99-28913 (under supervision of the Space and Naval Warfare Systems Center San Diego) and by the National Science foundation under grants FD99-79852 and CCR-0093337.