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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Semantic security ： ウィキペディア英語版 Semantic security In cryptography, a cryptosystem is semantically secure if any probabilistic, polynomial-time algorithm (PPTA) that is given the ciphertext of a certain message $m$ (taken from any distribution of messages), and the message's length, cannot determine any partial information on the message with probability non-negligibly higher than all other PPTA's that only have access to the message length (and not the ciphertext).〔S. Goldwasser and S. Micali, (Probabilistic encryption & how to play mental poker keeping secret all partial information ), Annual ACM Symposium on Theory of Computing, 1982.〕 In other words, knowledge of the ciphertext (and length) of some unknown message does not reveal any additional information on the message that can be feasibly extracted. This concept is the computational complexity analogue to Shannon's concept of perfect secrecy. Perfect secrecy means that the ciphertext reveals no information at all about the plaintext, whereas semantic security implies that any information revealed cannot be feasibly extracted.〔Goldreich, Oded. Foundations of Cryptography: Volume 2, Basic Applications. Vol. 2. Cambridge university press, 2004.〕 ==History== The notion of semantic security was first put forward by Goldwasser and Micali in 1982.〔 However, the definition they initially proposed offered no straightforward means to prove the security of practical cryptosystems. Goldwasser/Micali subsequently demonstrated that semantic security is equivalent to another definition of security called ciphertext indistinguishability under chosen-plaintext attack.〔S. Goldwasser and S. Micali, (Probabilistic encryption ). Journal of Computer and System Sciences, 28:270-299, 1984.〕 This latter definition is more common than the original definition of semantic security because it better facilitates proving the security of practical cryptosystems. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Semantic security」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.