A new proxy signature scheme providing self-delegation

Abstract

We improve Malkin et al's construction (Eurocrypt'04) of the proxy signature scheme in the random oracle model1. Unlike Malkin et al's scheme, the proposed scheme does not assume the existence of the trusted secure device, which has a global secret key that all users' private keys can be recovered with. This makes the proposed scheme more scalable and efficient because users need not access and cooperate with the secure device to generate their public/private key pairs. We show that the proposed scheme is provably secure based on the modified strong RSA assumption that was made by the Itkis et al (CRYPTO'01).