Identity-based aggregate and multi-signature schemes based on RSA

Abstract

We propose new identity-based multi-signature (IBMS) and aggregate signature (IBAS) schemes, secure under RSA assumption. Our schemes reduce round complexity of previous RSA-based IBMS scheme of Bellare and Neven [BN07] from three to two rounds. Surprisingly, this improvement comes at virtually no cost, as the computational efficiency and exact security of the new scheme are almost identical to those of [BN07]. The new scheme is enabled by a technical tool of independent interest, a class of zero-knowledge proofs of knowledge of preimages of one-way functions which is straight-line simulatable, enabling concurrency and good exact security, and aggregatable, enabling aggregation of parallel instances of such proofs into short multi/aggregate signatures. © 2010 Springer-Verlag Berlin Heidelberg.