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In cryptography, a sponge function or sponge construction is a class of algorithms with finite internal state that take an input bit stream of any length and produce an output bit stream of any desired length. Sponge functions have both theoretical and practical uses. They can be used to model or implement many cryptographic primitives, including cryptographic hashes, message authentication codes, stream ciphers, pseudo-random number generators and authenticated encryption.〔(【引用サイトリンク】title=Duplexing The Sponge )〕 ==Construction== A sponge function is built from three components:〔(【引用サイトリンク】title=Sponge Functions )〕 * a state memory, ''S,'' containing ''b'' bits, * a function, ''f'', of fixed length that permutes or transforms the state memory * a padding function ''P'' The state memory is divided into two sections: one of size ''r'' (the bitrate) and the other of size ''c'' (the capacity). These sections are denoted ''R'' and ''C'' respectively. The padding function appends enough bits to the input string so that the length of the padded input is a whole multiple of the bitrate, ''r.'' The padded input can thus be broken into ''r''-bit blocks. 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「Sponge function」の詳細全文を読む スポンサード リンク
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