密钥可撤销与密文可转换的密码算法研究

发布时间：2018-02-22 10:25

本文关键词： 密钥撤销身份基签密属性加密密文转化代理重加密　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：传统公钥密码体制中如果用户的密钥泄露,可以通过撤销用户的公钥来解决。但对基于身份的密码体制,用户的公钥就是用户唯一的身份信息,因此对公钥的细微修改或撤销都会引起用户身份信息的改变。因此,如何有效的在身份基密码体制中实现密钥撤销机制是很关键的。代理重加密中一个半可信的代理服务器能够将在一个公钥下加密的密文转化成在另一个公钥下加密的密文,而这两个密文对应着同一个明文并且代理不知道明文的任何信息。因此代理重加密在保证数据机密性的前提下实现了数据共享和数据转发的目的。如何设计安全高效的代理重加密方案对信息存储很有意义。鉴于以上所要解决的问题,本文的主要工作如下:1.提出了一个新的可撤销的基于身份的签密方案。在新方案中,将主密钥随机分成两部分,一部分用于构造初始密钥,另一部分用于生成更新密钥,然后再随机生成解/签密密钥,从而使方案不仅能够撤销用户,而且能够抵抗密钥泄露攻击。在标准模型下,证明了新方案基于DBDH困难问题假设具有IND-CCA2安全性,同时基于CDH困难问题假设具有EUF-CMA安全性。2.提出了一个新的密文策略的基于属性的多用户单向代理重加密方案,实现了细粒度访问控制下密文可多次转化的功能。在新方案中的访问树支持‘与’(?)和‘或’(?)门以及‘of’门限属性控制,并且所提方案具有重加密控制特性。在标准模型下证明了所提方案基于ADBDH困难假设具有IND-SAP-CCA安全性。
[Abstract]:In the traditional public key cryptosystem, if the key of the user is leaked, it can be solved by revoking the public key of the user, but for the identity-based cryptosystem, the public key of the user is the unique identity information of the user. Therefore, minor changes to the public key or revocation of the public key can cause changes in user identity information. How to effectively implement the key revocation mechanism in the ID-based cryptosystem is very important. A semi-trusted proxy server in proxy reencryption can convert ciphertext encrypted under one public key into a ciphertext encrypted under another public key. These two ciphertext correspond to the same plaintext and the agent does not know any information of plaintext. Therefore, proxy reencryption realizes the purpose of data sharing and data forwarding on the premise of ensuring the confidentiality of data. How to design security. An efficient proxy reencryption scheme is significant for information storage. The main work of this paper is as follows: 1. A new identity-based signcryption scheme is proposed. In the new scheme, the master key is randomly divided into two parts, one is used to construct the initial key, the other is used to generate the update key. Then the solution / signcrypt key is generated randomly, so that the scheme can not only undo the user, but also resist the key leak attack. Under the standard model, it is proved that the new scheme is IND-CCA2 secure based on the assumption of DBDH difficult problem. At the same time, based on the assumption that CDH has EUF-CMA security. 2. A new encryption strategy based on attributes is proposed, which is a multi-user one-way proxy reencryption scheme. The function of converting ciphertext multiple times under fine-grained access control is realized. And'or'? The proposed scheme has the property of reencryption control. It is proved that the proposed scheme is IND-SAP-CCA secure based on the ADBDH difficult assumption in the standard model.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN918.4

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