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消息认证码是现代密码学中用以检验数据完整性和数据起源认证的重要手段.分组密码认证模式是利用分组密码为基础部件来实现认证功能的一种工作模式.安全和效率是消息认证码的设计过程中需要权衡的两个方面.为了提高分组密码认证模式的效率,2009年,黄玉划等人提出了一种基于链接与计数的快速认证模式(CCTR),并从统计评估的角度验证了CCTR模式的安全性.本文利用底层分组密码的特性,分别从实际攻击的角度和可证明安全性的角度对CCTR模式的安全性进行了分析.利用CCTR模式中部分分组密码密钥输入部分可控的特点,我们进行选择消息攻击.两种攻击方法只需对标签生成算法询问一次,就可以伪造成功.研究结果表明:在CCTR模式实际使用中,当所用分组密码具有一个和DES相同的性质时,CCTR模式是不安全的;当所用分组密码是一个有弱密钥的伪随机置换时,CCTR模式也是不安全的.同时表明,原文中CCTR模式的安全性证明是错误的,仅仅在伪随机置换的假设下,不足以证明CCTR模式安全性.
Message authentication code is used in modern cryptography to verify the integrity of data and data origin authentication is an important means.Group password authentication mode is the use of block cipher-based components to achieve the authentication function of a working mode.Security and efficiency of the message authentication code In order to improve the efficiency of packet password authentication mode, in 2009, Huang et al proposed a fast authentication mode based on link and count (CCTR), and from the perspective of statistical evaluation The security of CCTR mode is analyzed in this paper.Based on the characteristics of the underlying packet cipher, this paper analyzes the security of CCTR mode from the perspective of practical attack and the point of view of verifiable security.Using some of the partial block cipher key input in CCTR mode Control characteristics, we choose the message attack.The two attack methods need only tag generation algorithm query, you can forge success.Research results show that: in the actual use of CCTR mode, when the block password used has the same property and DES , The CCTR mode is insecure; when the used block cipher is a pseudo-random permutation with a weak key, the CCTR mode Is also unsafe. At the same time, it shows that the security of the CCTR model in the original text is wrong, which is not enough to prove the CCTR mode security under the assumption of pseudo-random permutation.