广播加密的自适应安全性

发布时间：2018-11-13 13:04

【摘要】：随着广播通信技术的不断发展,广播系统的安全问题愈发引人关注,广播加密逐渐成为密码学领域的研究热点。而安全模型是刻画密码方案安全性的重要工具,近十几年的研究进展显示,广播加密的安全模型主要有三种,分别是静态安全、半静态安全以及自适应安全。但是在现实生活中网络环境复杂多样,多用户、多挑战环境逐渐成为构建安全密码方案需要考虑的重要因素。如何将传统安全模型扩展到多挑战环境成为研究人员重点关注的方向。本文在传统广播加密安全模型的基础上提出两种更强的广播加密安全模型,即多挑战环境下半静态安全模型(MS安全)与多挑战环境下自适应安全模型(MA安全),并研究了广播加密方案在多挑战环境下与单挑战环境下安全性之间的关系,给出一个广义结论,即单挑战环境下自适应安全的广播加密在多挑战环境下可以达到自适应安全,但存在一个与加密询问次数相关的归约损失。为了构造多挑战环境下更紧的自适应安全的广播加密方案,本文研究了两种构造方法。第一种来源于Gentry和Waters方案的转换技术,即利用半静态安全的广播加密方案构造自适应安全的广播加密方案。我们发现此种技术同样适用于构造MA安全的广播加密方案,但存在来源于对称加密方案的安全归约损失。此外,该类构造方案的安全性依赖于较强的q类型假设,为了进一步移除该假设,我们的第二种方法是将Hofheinz-Koch-Striecks技术应用到Gentry-Waters的半静态安全的广播加密方案中,并给出了一个在合数阶上实例化的MA安全的广播加密方案。两种方法都可以将Gentry-Waters半静态的广播加密方案转化为多挑战环境下自适应安全的方案,且密文头部大小为常数。
[Abstract]:With the development of broadcast communication technology, the security of broadcast system has attracted more and more attention. Broadcast encryption has become a research hotspot in the field of cryptography. The security model is an important tool to describe the security of cryptographic schemes. The recent research progress shows that there are three main security models of broadcast encryption, namely static security, semi-static security and adaptive security. However, in real life, the network environment is complex and diverse, multi-user, multi-challenge environment has gradually become an important factor to be considered in the construction of a secure cryptographic scheme. How to extend the traditional security model to multi-challenge environment has become the focus of attention. Based on the traditional broadcast encryption security model, this paper proposes two stronger broadcast encryption security models, i.e. semi-static security model (MS security) in multi-challenge environment and adaptive security model (MA security) in multi-challenge environment. The relationship between the security of broadcast encryption scheme in multi-challenge environment and single-challenge environment is studied, and a generalized conclusion is given that the adaptive security of broadcast encryption in single-challenge environment can achieve adaptive security in multi-challenge environment. However, there is a reduction loss associated with the number of encrypted queries. In order to construct a more compact adaptive secure broadcast encryption scheme in a multi-challenge environment, two construction methods are studied in this paper. The first one comes from the conversion technology of Gentry and Waters schemes, which uses semi-static secure broadcast encryption schemes to construct adaptive secure broadcast encryption schemes. We find that this technique is also suitable for constructing MA secure broadcast encryption scheme, but there is a loss of security reduction due to symmetric encryption scheme. In addition, the security of this kind of construction scheme depends on the strong Q type hypothesis. In order to remove this assumption further, our second method is to apply Hofheinz-Koch-Striecks technology to Gentry-Waters 's semi-static secure broadcast encryption scheme. A secure broadcast encryption scheme for MA is also presented in this paper. Both methods can transform Gentry-Waters semi-static broadcast encryption scheme into adaptive security scheme in multi-challenge environment, and the size of ciphertext header is constant.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN93;TP309.7

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