Attainable Unconditional Security for Shared-Key Cryptosystems
Attainable Unconditional Security for Shared-Key Cryptosystems
复制标题
共享密钥密码系统可实现的无条件安全性
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Axel Legay
中科院分区：
文献类型：
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作者：
Fabrizio Biondi;Thomas Given;Axel Legay
保护私人通信的隐私是加密解决的计算的基本问题。信息理论推理模型无条件的安全性，其中结果的强度不受计算难度或未经证实的结果的影响。完美保密通常被认为是密码系统的理想结果，其中密文的知识不会透露有关密钥或消息的信息，但通常这在实践中是不可能实现的。另一种度量是模糊度，直观地说，可以产生给定密文的消息/密钥对的平均数量。我们展示了一个理论上的界限含糊称为最大含糊，并表明，这概括了完美的保密时，实现，并提供了一种替代措施时，完美的保密是不是。我们推导出最大含糊度的界限，并表明，反直观的最大含糊度时实现的密文的熵最小化。我们认为，在这种新的信息下的加密功能，并表明，在一般的理论上最好的是无法实现的，一些流行的方法，如拉丁广场或crossigroups也不是最佳的。我们提出了一些算法，用于生成加密功能，是实用的，并实现90-95%的理论最好的，改进与更大的消息空间。
Preserving the privacy of private communication is a fundamental concern of computing addressed by encryption. Information-theoretic reasoning models unconditional security where the strength of the results is not moderated by computational hardness or unproven results. Perfect secrecy is often considered the ideal result for a cryptosystem, where knowledge of the ciphertext reveals no information about the key or message, however often this is impossible to achieve in practice. An alternative measure is the equivocation, intuitively the average number of message/key pairs that could have produced a given ciphertext. We show a theoretical bound on equivocation called max equivocation and show that this generalizes perfect secrecy when achievable, and provides an alternative measure when perfect secrecy is not. We derive bounds for max-equivocation, and show that counter intuitively max-equivocation is achieved when the entropy of the ciphertext is minimized. We consider encryption functions under this new information, and show that in general the theoretical best is unachievable, and that some popular approaches such as Latin squares or Quasigroups are also not optimal. We present some algorithms for generating encryption functions that are practical and achieve 90-95% of the theoretical best, improving with larger message spaces.