非对称双线性对下的基于身份的加密方案

基于身份的加密是一种直接以用户的身份作为公钥的加密方案。自提出以来,利用双线性对实现基于身份的加密方案的案例已经有很多,但是这些方案大都是采用对称的双线性对,即要求作为映射输入的两个群相同。这无疑缩小了映射中所选取的椭圆曲线的范围,将在一种更一般的条件下,即在非对称双线性对下,基于判定性双线性Diffe-Hellman（BDHE）难解问题在标准模型下构造出一种新型的基于身份的加密方案,并证明其在标准模型下具有不可区分的选择身份的选择明文（IND-sID-CPA）安全性。

Identity-Based Encryptionfrom the Asymmetric Bilinear Pairings

Identity-based encryption is a method which directly uses the user＇ s identity as its public key. Since it appears, there are a lot of identity-based encryption schemes from bilinear pairings, but most of these schemes uses symmetric bilinear pairings as their math tools, namely the groups as it put in the bilinear mapping should be the same one. This would greatly reduce the scope of the available elliptic curves in the encryption schemes. This paper proposes a new type of identity-based encryption scheme from the asymmetric bilinear pairings without using random oracles, in a more general bilinear pairings conditions, and proves that it has indistinguishable selective-ID CPA security by reducing it to decision-BDH problem under the standard model.