Scrutinizing and Improving Impossible Differential Attacks: Applications to CLEFIA, Camellia, LBlock and Simon (Full Version)
Scrutinizing and Improving Impossible Differential Attacks: Applications to CLEFIA, Camellia, LBlock and Simon (Full Version)
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DOI：
10.1007/978-3-662-45611-8_10
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发表时间：
2014-09
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影响因子：
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通讯作者：
Christina Boura;M. Naya-Plasencia;Valentin Suder
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文献类型：
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作者：
Christina Boura;M. Naya-Plasencia;Valentin Suder
不可能差分密码分析已被证明是针对分组密码的一种非常强大的密码分析形式。这些攻击即使被广泛使用，由于其技术性很高，仍然没有被完全理解。事实上，许多应用程序都已发现错误或攻击缺乏最优性。本文的第一步旨在形式化和改进此类攻击，第二步是将我们的工作应用于基于 Feistel 构造的分组密码。在此背景下，我们推导出用于发起此类攻击的通用复杂性分析公式，并开发了优化不可能差分密码分析的新想法。这些想法包括例如测试部分内部状态以减少所涉及的密钥位的数量。我们还以更通用的方式开发了使用多个差分路径的概念，这是之前在更受限制的背景下引入的想法。这些进步改进了之前针对 CLEFIA-128 和 Camellia 等知名密码的攻击，同时还改进了针对 23 轮 LBlock 和 Simonfamily 所有成员的新攻击。
Impossible differential cryptanalysis has shown to be a very powerful form of cryptanalysis against block ciphers. These attacks, even if extensively used, remain not fully understood because of their high technicality. Indeed, numerous are the applications where mistakes have been discovered or where the attacks lack optimality. This paper aims in a first step at formalizing and improving this type of attacks and in a second step at applying our work to block ciphers based on the Feistel construction. In this context, we derive generic complexity analysis formulas for mounting such attacks and develop new ideas for optimizing impossible differential cryptanalysis. These ideas include for example the testing of parts of the internal state for reducing the number of involved key bits. We also develop in a more general way the concept of using multiple differential paths, an idea introduced before in a more restrained context. These advances lead to the improvement of previous attacks against well known ciphers such as CLEFIA-128 and Camellia, while also to new attacks against 23-round LBlock and all members of theSimonfamily.