On the Incremental Asymmetric Signatures

The purpose of incremental cryptography is to allow the updating of cryptographic forms of documents undergoing modifications, more efficiently than if we had to recompute them from scratch. This paper defines a framework for using securely a variant of the incremental hash function designed by Bok-Min Goi et al. The condition of use of their hash function is somehow impractical since they assume that the blocks of the message are all distinct. In this paper we show how we can discard this strong assumption so as to construct the first practical incremental asymmetric signature scheme that keeps efficient update operations. Finally, as the proposed scheme has the defect to severely expand the signature size, we propose a solution which drastically reduces this drawback.