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A null cipher is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material. It would today be regarded as a simple form of steganography. Null ciphers can also be used to hide ciphertext, as part of a more complex system. In classical cryptography a ''null'' is intended to confuse the cryptanalyst. Typically, a null will be a character which decrypts to obvious nonsense at the end of an otherwise intelligible phrase. In a null cipher, most of the characters may be nulls. An example follows (Kipper 9): :''News Eight Weather: Tonight increasing snow. Unexpected precipitation smothers eastern towns. Be extremely cautious and use snowtires especially heading east. The (is not ) knowingly slippery. Highway evacuation is suspected. Police report emergency situations in downtown ending near Tuesday.'' Taking the first letter in each word successively yields the real message: "Newt is upset because he thinks he is President." You can also choose to instead use the last letter of every word, or something like a pattern such as: ''Susan sAys GaIl Lies. MAtt leTs Susan fEel joVial. Elated (or) aNgry? '' Using the pattern (1,2,3,1,2,3 (letter in each word )) gives the message: "Sail at seven." ==See also== * Null encryption 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「Null cipher」の詳細全文を読む スポンサード リンク
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