Characterization Of The Relations Between Information-Theoretic Non-Malleability, Secrecy, And Authenticity
ICITS'11: Proceedings of the 5th international conference on Information theoretic security(2011)
摘要
Roughly speaking, an encryption scheme is said to be non-malleable, if no adversary can modify a ciphertext so that the resulting message is meaningfully related to the original message. We compare this notion of security to secrecy and authenticity, and provide a complete characterization of their relative strengths. In particular, we show that information-theoretic perfect non-malleability is equivalent to perfect secrecy of two different messages. This implies that for n-bit messages a shared secret key of length roughly 2n is necessary to achieve non-malleability, which meets the previously known upper bound. We define approximate non-malleability by relaxing the security conditions and only requiring non-malleability to hold with high probability (over the choice of secret key), and show that any authentication scheme implies approximate non-malleability. Since authentication is possible with a shared secret key of length roughly log n, the same applies to approximate non-malleability.
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关键词
approximate non-malleability,secret key,information-theoretic perfect non-malleability,authentication scheme,different message,encryption scheme,n-bit message,original message,perfect secrecy,resulting message,information-theoretic non-malleability
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