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Methodologies for designing block ciphers and cryptographic protocols.

机译：设计分组密码和密码协议的方法。

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摘要

This thesis concerns two subjects whose primary applications are in the field of cryptography: reversible programs and multi-party protocols.The first part of the thesis investigates a model of computation called a "reversible program", and its relationship to the level of cryptographic security attainable by a "simple product cipher" (which is a type of method for encrypting fixed-length blocks of data).The notion of a simple product cipher is motivated by the design of some ciphers, including the widely used Data Encryption Standard.Informally, reversible programs and simple product ciphers both have the property that they can be expressed as a composition of "very simple" permutations on the set of n-bit binary strings. We show that, under a cryptographic assumption (namely, that there exists a pseudorandom function generator that is feasibly computed by a particular kind of computation, called an "iterated integer matrix product"), there exists a cryptographically secure simple product cipher. This can be regarded as progress towards showing that a secure simple product cipher exists. A by-product of our investigation of reversible programs is a result of independent interest in the field of algebraic complexity theory: over an arbitrary ring, any polynomial-size algebraic formula is computed by an algebraic straight-line program that uses only three registers.The second part of the thesis investigates the cryptographic security attainable in two-party protocols that carry out "collective coin flipping" transactions (or "games"), and "secret bit exchanging" transactions. In both cases, we construct protocols that, under some widely believed number theoretic intractability assumptions, attain various levels of security for the transaction. We also prove some non-trivial lower bounds on the level of security attainable by any protocol for either of the transactions.
机译：本文涉及两个主要在密码学领域中应用的主题：可逆程序和多方协议。本文的第一部分研究了称为“可逆程序”的计算模型及其与密码安全级别的关系。可以通过“简单乘积密码”（一种对固定长度的数据块进行加密的方法）来实现。简单乘积密码的概念是受某些密码设计的启发，其中包括广泛使用的数据加密标准。 ，可逆程序和简单乘积密码都具有可以将它们表示为n位二进制字符串集上“非常简单”排列的组合的特性。我们证明，在密码学假设下（即，存在一个伪随机函数生成器，可以通过一种特殊的计算方式来计算该伪随机函数生成器，称为“迭代整数矩阵乘积”），存在一种密码学安全的简单乘积密码。这可以看作是显示存在安全的简单产品密码的进展。我们对可逆程序进行研究的副产品是代数复杂性理论领域的独立兴趣的结果：在任意环上，任何多项式大小的代数公式都是由仅使用三个寄存器的代数直线程序计算的。论文的第二部分研究了在执行“集体硬币翻转”交易（或“游戏”）和“秘密比特交换”交易的两方协议中可获得的密码安全性。在这两种情况下，我们都构造了一些协议，这些协议在一些普遍认为的数字理论上难以处理的假设下，可以为交易提供各种级别的安全性。我们还证明了任何协议对任何一个事务所能达到的安全级别的一些重要限制。

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  • 作者

    Cleve, Richard Erwin.;

  • 作者单位

    University of Toronto (Canada).;

  • 授予单位 University of Toronto (Canada).;
  • 学科 Computer Science.
  • 学位 Ph.D.
  • 年度 1989
  • 页码 无
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  • 原文格式 PDF
  • 正文语种 eng
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