Using gap Diffie-Hellman groups

based partially blind signature scheme

an efficient ID-based partially blind signature scheme without trusted private key generator （PKG） was proposed. In this scheme

PKG was prevented from forging a legal user’s signature because it only generated partial private key. Under the random oracle model

the proposed scheme was proved to be secure against existential forgery on adaptively chosen message and ID attack. The security of scheme relied on the hardness of the computational Diffie-Hellman problem （CDHP）. The proposed scheme satisfies security properties: correctness and partial blindness. Compared with the Chow et al.’s scheme

the new scheme needs less computational cost and is more efficient.