标准模型下一种新的基于分级身份的短签名方案

A New Construction of Short Hierarchical Identity-Based Signature in the Standard Model

基于分级身份的签名在大规模网络中具有重要应用前景,为克服已有方案的私钥或签名长度依赖于分级级数及最大分级级数的缺陷,提高计算效率,提出了一种新的基于分级身份的签名方案.与已有方案相比,新方案优势明显,如身份分级级数越大,私钥长度越短,且签名长度为常数,仅含有3个群元素.验证算法仅需要3个双线性对运算,同样不依赖于分级级数.另外,新方案的安全性建立在推广的选择身份安全模型,该模型为适应性选择身份安全模型及选择身份安全模型的推广,在计算h-CDH困难假设下,新方案被证明是安全存在性不可伪造的,且其安全性不依赖于随机预言机.与已有的标准模型下的分级方案相比,新方案的安全性基于的困难假设更具有一般性.

Hierarchical identity based signature （HIBS） has wide application in large scale networks. However, the existing work cannot solve the trade-off between security and efficiency. The main challenge at present is to construct a high efficient and strongly secure HIBS with low computation cost. To overcome the drawbacks in the previous work, a new hierarchical identity-based signature scheme is introduced. The proposed scheme has some advantages over the available. For examples, the private keys size shrinks as the identity depth increases, the signature only consists of three group elements and three bilinear pairs are needed in verifying algorithm, which are independent of hierarchy depth. Furthermore, the security of the new scheme is based on the general selective-identity security model（Gs-ID） which is a general security model based on full security model and selective identity model. Under the h-computational Diffie-Hellman exponent problem （h-CDH） assumption, our scheme is proven to be secure against Gs-ID and adaptive chosen message attack. In addition, the security analysis does not rely on the random oracles. The assumption in our scheme is more natural than many of the hardness assumptions recently introduced to HIBS in the standard model, which solves the trade-off between the security and computation efficiency.