基于身份的高效签密密钥封装方案

An ID-Based Efficient Signcryption Key Encapsulation Scheme

KEM-DEM结构的混合密码体制是获得IND-CCA安全最实际有效的方法,传统的KEM由公钥加密方案实现,仅提供DEM使用的会话密钥的保密性安全.2005年Alexander等人将签密的概念与KEM-DEM结构的混合密码体制相结合,提出了Signcryption KEM-DEM结构的混合签密.其中Signcryption KEM是利用发送者私钥和接收者公钥共同生成会话密钥及其密钥封装.该方法可以使密钥封装同时具有保密安全性和不可伪造安全性.在基于身份密码体制上扩展了签密密钥封装的定义,结合Sakai-Kasahara私钥提取结构以及椭圆曲线上相关的困难问题给出了一个基于身份的签密密钥封装的实例方案,并在随机预言机模型下对该实例方案的安全性进行了证明.该方案具有ID-IND-CCA保密性安全和ID-UF-CMA不可伪造性安全.提出的实例方案在会话密钥封装阶段不需要进行对计算以及映射到点的Hash函数计算.通过有效的对优化计算和点压缩技术,本实例方案在具有高安全性的同时也具有执行性能上的优势.

Hybrid schemes in a KEM-DEM structure is regarded as the most natural approach to public key encryption with IND-CCA security and practical efficiency. Traditional KEM is realized by public key scheme, which only provides confidentiality security for session key used by DEM. In 2005, combining the idea of signcryption with the KEM-DEM model hybrid encryption, Alexander proposed a signcryption KEM-DEM model hybrid signcryption primitive. Signeryption KEM means that the sender＇s private key and the receiver＇s public key are used together to generate session key and key encapsulation. Compared with traditional KEM scheme, Signcryption KEM can provide both confidentiality security and unforgeability security for session key. In this paper the definition of signcryption KEM is extended in ID-based cryptography. Based on Sakai-Kasahara identity-based key contracture and elliptic-curves-related hard problems, an instance scheme of ID-based signeryption key encapsulation is proposed. Security properties of the proposed scheme are proven with the random oracle model. The proposed scheme is ID-IND-CCA secure in confidentiality and ID-UF-CMA secure in unforgeability. At the encapsulation phase of the proposed scheme, no paring computing and no MapToPoint hash function are required. According to the recent advances in pairings optimized computing and point reduction, the proposed scheme is not only secure but also has advantage in performance.