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The VIC cipher was a pencil and paper cipher used by the Soviet spy Reino Häyhänen, codenamed "VICTOR". If the cipher were to be given a modern technical name, it would be known as a "straddling bipartite monoalphabetic substitution superenciphered by modified double transposition."〔 David Kahn. ("Number One From Moscow" ). 1993. 〕 However, by general classification it is part of the Nihilist family of ciphers. It was arguably the most complex hand-operated cipher ever seen, when it was first discovered. The initial analysis done by the NSA in 1953 did not absolutely conclude that it was a hand cipher, but its placement in a hollowed out 5c coin implied it could be broken by pencil and paper. The VIC cipher remained unbroken until more information about its structure was available. Although certainly not as complex or secure as modern computer operated stream ciphers or block ciphers, in practice messages protected by it resisted all attempts at cryptanalysis by at least NSA from its discovery in 1953 until Häyhänen's defection in 1957. ==A revolutionary leap== The VIC cipher can be regarded as the evolutionary pinnacle of the Nihilist cipher family. The VIC cipher has several important integrated components, including mod 10 chain addition, a lagged Fibonacci generator (a recursive formula used to generate a sequence of pseudorandom digits), a straddling checkerboard, and a disrupted double transposition. Until the discovery of VIC, it was generally thought that a double transposition alone was the most complex cipher an agent, as a practical matter, could use as a field cipher. 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「VIC cipher」の詳細全文を読む スポンサード リンク
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