Statistical cryptanalysis of block ciphers as channel communication

摘要：分组密码是通信基础设施中不可或缺的组成部分，但其设计和分析的统一原则却很少。因此，不可能容易地描述好密码和坏密码的特征，并且好密码的设计是困难的。虽然存在显著的一般处理的问题，并提供了宝贵的见解，它一直很难联合收割机的具体攻击和具体的密码设计到一个总体的理论，还有很多工作要做。本项目研究的一大类攻击称为统计密码分析，利用明文，密钥和密文之间的概率关系，以确定密钥。该研究扩展了现有的统计密码分析的通信信道模型-其中低容量信道携带密钥的编码符号给对手-已经非常成功地用于设计对流密码的攻击，但没有广泛用于分组密码分析。该项目利用的一个关键见解如下：现有的密码分析模型没有提供研究相关密钥攻击和统计攻击组合的方法。PI观察到相关秘密在信息泄漏信道上形成代码，提高了对手的通信效率。使用这种方法，该项目获得了攻击效率的一般结果-尽可能地实验验证-和相关的密码设计标准。通过与当地高中尚蒂伊学院建立关系，PI教授密码学模块，该项目有助于K-12教育，并激励高中生学习数学，工程和计算机科学。

Abstract: Block ciphers are indispensable components of the communication infrastructure, yet few unifying principles for their design and analysis exist. As a result, it is not possible to easily characterize good and bad ciphers, and the design of good ciphers is difficult. While notable general treatments of the problem do exist and have contributed valuable insights, it has been difficult to combine the individual treatments of specific attacks and specific cipher designs into an overarching theory, and much remains to be done.This project studies a large class of attacks known as statistical cryptanalysis, which exploits probabilistic relationships among the plaintext, key and ciphertext to determine the key. The research extends existing communication channel models of statistical cryptanalysis---where low capacity channels carry encoded symbols of the key to the adversary---which have been used very successfully to design attacks on stream ciphers, but are not as widely used for block cipher cryptanalysis. A key insight exploited by the project is as follows: existing cryptanalytic models do not provide a means of studying the combination of related-key attacks and statistical attacks. The PI observed that related secrets form codes over information leakage channels, improving adversary communication efficiency. Using this approach, the project obtains general results on attack efficiency---experimentally verified as far as possible---and related cipher design criteria. Through an established r elationship with local high school Chantilly Academy, where the PI teaches cryptography modules, the project contributes to K-12 education, and inspires high school students to study mathematics, engineering and computer science.