Trapdoor sanitizable signatures made easy

Abstract

A sanitizable signature scheme allows a signer to partially delegate signing rights on a message to another party, called a sanitizer. After the message is signed, the sanitizer can modify pre-determined parts of the message and generate a new signature on the sanitized message without interacting with the signer. At ACNS 2008, Canard et al. introduced trapdoor sanitizable signatures based on identity-based chameleon hashes, where the power of sanitization for a given signed message can be delegated to possibly several entities, by giving a trapdoor issued by the signer at any time. We present a generic construction of trapdoor sanitizable signatures from ordinary signature schemes. The construction is intuitively simple and answers the basic theoretic question about the minimal computational complexity assumption under which a trapdoor sanitizable signature exists; one-way functions imply trapdoor sanitizable signatures. © 2010 Springer-Verlag Berlin Heidelberg.