近年来，基于身份的密码体制研究受到了广泛关注。不同于传统公钥密码体制，基于身份的加密体制（IBE）可直接利用用户的身份标识作为公钥，不需要使用数字证书，密钥管理简单，这使其成为公钥加密领域的一个研究热点。目前，已有的身份加密体制大多是基于椭圆曲线上的双线性对来构造的，然而双线性群上的乘法和指数运算较慢，参数选择过于复杂，导致计算效率较低，这使得基于双线性对构造的身份加密方案难以走向实用。传统公钥密码体制所依赖的标准大整数分解问题计算效率较好，是用于构造安全实用的基于身份的加密体制的另一个方向。文章综述了基于大整数分解的身份加密体制的最新研究进展，概述了基于身份的加密体制的定义和安全模型，总结了基于身份的加密体制的研究现状；对几种典型的基于大整数分解的身份加密算法进行了对比、分析，总结各算法的优劣；对基于身份的加密体制中存在的热点问题进行剖析，并提出有价值的问题供进一步研究。%Recently, research on identity-based encryption (IBE) has received extensive attentions. Different from the traditional public-key cryptosystem, IBE applies the user’s identity directly as a public key rather than the digital certiifcate, and the key management is simple, which makes the IBE become a research hotspot in the ifeld of public-key encryption. Nowadays, IBE is often constructed using bilinear pairing on elliptic curve. But the multiplication and exponential operations based on bilinear group are slow and inefficient, and the parameters selection is too complicated. Therefore, the IBE constructed based on bilinear pairing is not practical. The standard large integer factorization of the traditional public-key cryptosystem is better, which is the other direction for the construction of a safe and practical IBE. This paper describes the research progress of the IBE based on large integer factorization, introduces the definition and the security model of the IBE, and summarizes current research achievements on the IBE. This paper also compares and analyzes several typical IBE algorithms based on large integer factorization, and summarizes the advantages and disadvantages of each algorithm. In addition, this paper analyzes the hot issues of IBE, and puts forward some valuable problems for further research.
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