On the security of an enhanced signature scheme

Abstract

Currently, short signature is receiving significant attention since it is particularly useful in low-bandwidth communication environments. However, most of the short signature schemes are only based on one intractable assumption. Recently, Su presented an identity-based short signature scheme based on knapsack and bilinear pairing. He claimed that the signature scheme is secure in the random oracle model. Unfortunately, in this paper, we show that his scheme is insecure. Concretely, an adversary can forge a valid signature on any message with respect to any identity in Su's scheme.

Lattice-Based Multi-Signature Schemes

“…This method can be applied to construct hierarchical identity-based encryption that is secure in standard model. In recent years, many lattice-based cryptosystems such as lattice-based group signature scheme [6], lattice-based blind signature scheme [7], lattice-based ring signature scheme [8], lattice-based threshold ring signature scheme [9], lattice-based proxy signature schemes [10,11,12], verifiably encrypted signature scheme [13] and strong designate verifier signature scheme [14] are proposed successively. However, most existing digital multi-signature schemes [15,16,17] are designed on the Integer Factorization Problem, the Discrete Logarithm Problem and so on.…”