# Ps4

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Unformatted text preview: se of keys U to p , where p is prime. Later, Alice sends a message m to Bob over the Internet, where m U . She authenticates this message to Bob by also sending an authentication tag t = h(m), and Bob checks that the pair (m, t) he receives satisfies t = h(m). Suppose that an adversary intercepts (m, t) en route and tries to fool Bob by replacing the pair with a different pair (m , t ). Argue that the probability that the adversary succeeds in fooling Bob into accepting (m , t ) is at most 1/p, no matter how much computing power the adversary has, even if the adversary knows the family H of hash functions used....
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## This note was uploaded on 07/09/2009 for the course CSE 6.046J/18. taught by Professor Piotrindykandcharlese.leiserson during the Fall '04 term at MIT.

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