A robust (k, n) + 1 threshold proxy signature scheme based on factoring

Proxy signature is an active cryptographic research area. Since Mambo et al. introduced the concept of proxy signature in 1996, many proxy signature schemes have been proposed. However, most of these previously proposed schemes are based on discrete logarithm problems. In this paper, we would like to propose a new robust (k, n) + 1 threshold proxy signature scheme based on factoring. In this scheme, generating a valid proxy signature needs not only any k or more members in n proxy signers but also a trusted dealer to cooperatively sign a message. To our best knowledge, this is the first (k, n) + 1 threshold proxy signature scheme based on factoring.