基于时间分割代理加密的一般性构造方法

计算机工程与科学

基于时间分割代理加密的一般性构造方法

郑志伟，黄振杰

（闽南师范大学计算机学院,福建漳州 363000）

收稿日期:2015-10-12 修回日期:2015-12-07 出版日期:2016-11-25 发布日期:2016-11-25
基金资助:
国家自然科学基金(61170246);福建省中青年教师教育科技项目（JA14202）

A generic construction of proxy cryptosystem

based on time segmentation

ZHENG Zhiwei，HUANG Zhenjie

(School of Computer Science,Minnan Normal University,Zhangzhou 363000,China)

Received:2015-10-12 Revised:2015-12-07 Online:2016-11-25 Published:2016-11-25

摘要/Abstract

摘要：

基于时间分割代理加密是一种典型的代理密码方案，可以将解密权委托给代理解密者，从而减轻原解密者的解密负担，具有广泛的应用前景，但研究成果相对较少。基于身份加密可直接将用户的身份标识作为公钥，简化了公钥证书的管理，近年来受到广泛关注，研究者提出很多方案。根据基于时间分割代理加密和基于身份加密在算法构成和安全模型两方面的区别与联系，提出一个基于时间分割代理加密的一般性构造方法，并证明其安全性。该方法可将任意一个安全的基于身份加密方案转换成安全的基于时间分割代理加密方案。通过该方法得到标准模型下安全的基于时间分割代理加密方案，大大丰富了基于时间分割代理加密方案的数量和类型。

关键词: 代理密码, 基于身份加密, 一般性转换, 可证明安全

Abstract:

Proxy cryptosystem based on time segmentation (PCBTS) is a typical proxy cryptosystem, which can delegate decryption right to the proxy decryptor, thus alleviating the burden of the original decryptor. Although it has broad application prospects, related research results are not plentiful. Identitybased encryption (IBE) applies the user’s identity directly as a public key, thus the management of the public key certificate is simplified. It therefore has attracted many researchers to put forward a large number of schemes in recent years. According to the differences and similarities between the PCBTS and the IBE in the aspects of algorithm structure and security model, we propose a generic construction method for the PCBTS with a proof of its security. Using the proposed method, any secure IBE scheme can be transformed into a secure PCBTS. We apply this method to an actual case and obtain a secure PCBTS in the standard model, which greatly enriches the quantity and type of PCBTS.

Key words: proxy cryptography, identitybased encryption, generic transformation, security proof

郑志伟，黄振杰. 基于时间分割代理加密的一般性构造方法[J]. 计算机工程与科学.

ZHENG Zhiwei，HUANG Zhenjie.

A generic construction of proxy cryptosystem

based on time segmentation

[J]. Computer Engineering & Science.

参考文献

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附录1Waters基于身份加密方案［14］

·系统初始化算法:
-令G，G1为素数p阶循环群，且存在可计算的双线性映射G×G→G1；
-随机选取α∈Zp；
-随机选择G的生成元g，计算g1=gα；
-随机选取g2∈G，u′∈G和长度为n的向量U=(ui)；
-该系统公共参数为params={g,g1,u′,U}，主公钥mpk=g2，主私钥为msk=gα2。
·密钥生成算法：
-令v为n比特字符串，用来表示身份，vi表示v的第i个比特；

-V{1,…,n}是满足vi=1的所有i的集合；

-随机选取r∈Zp；
-计算dv=(gα2(u′∏i∈vui)r,gr)。
·加密算法：
-随机选取t∈Zp；
-输出密文C=<C1,C2,C3>，其中C1=e(g1,g2)tm，C2=gt，C3=(u′∏i∈vui)t。
·解密算法：
-使用dv=(d1,d2)解密如下：
C1e(d2,C3)e(d1,C2)=(e(g1,g2)tm)e(gr,(u′∏i∈vui)t)e(gα2(u′∏i∈vui)r,gt)=

(e(g1,g2)tm)e(g,(u′∏i∈vui)rt)e(g1,g2)te((u′∏i∈vui)rt,g)=m

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