Convertible Undeniable Partially Blind Signature from Bilinear Pairings

Undeniable signature is a kind of signatures that the validity or invalidity of a signature can only be verified with the help of the signer. On the other hand, the concept of blind signature is to enable a user to obtain a signature on a message which is unknown to the signer. Following these pioneer works, extended version of these schemes such as convertible undeniable signatures and partially blind signatures have been proposed. We notice that these two signature schemes are investigated independently. However, in some situations, we may hope to have a signature scheme which can provide both the convertible-undeniable property and the property of partially blindness. A few works have done in this field but most of them are inefficient. In this paper, we propose a new convertible partially blind signature scheme. Our scheme provides a new property called universal conversion. Moreover, our scheme has the advantage of low communication cost in the process of signature generation comparing with current schemes.