PS基于身份数字签名算法的改进

PS（Paterson and Schuldt）算法直接利用两组独立的Waters身份处理函数分别处理用户身份和签名消息，该算法的安全归约效率很低。为此，改进了Waters身份处
理函数的参数选择方法，并将其应用于PS签名算法安全证明的改进，使新的基于身份数字签名算法安全归约效率大大提高，从PS方案的O((q_kn)^-2)提高到O((q_kn)^-1)，从而使新算法更加安全、可信。

Improvement on PS Identity Based Signature Scheme

In the standard model an unforgeable chosen message attacks security IBS(Identity-Based Signature) scheme was proposed by PS(Paterson and Schuldt),which was based on computational Diffie-Hellman problem in bilinear pairing group.Two independent Waters identity hash functions were directly employed to treat the users identity and the signature message respectively,so PSs IBS scheme had poor security reduction efficiency.An improved Waters identity hash function parameters selecting method was proposed.The new method was employed to improve PSs IBS signature scheme,which made the security reduction efficiency of the new IBS scheme having greatly improvementfrom O((qkn)-2) to O((qkn(n~1/2)))-1),so the improved scheme was more security and trustable.