Vernam cipher

In cryptography, an early stream cipher developed for the printing telegraph in 1917. The plaintext characters, encoded into binary form, are punched on a paper tape; a set of random numbers, also expressed in binary form, is punched onto a second tape. The two tapes are read in synchronism, the numbers added modulo2, and a corresponding ciphertext tape is produced. The receiving end is supplied with a tape containing the same cryptographic bit stream and the plaintext is revealed by modulo 2 addition of the ciphertext and cryptographic bit stream.; 在密碼學中，于1917年為印刷電報開發的一種早期序列密碼。明文字母按二進制編碼，打到 紙帶上；一組隨機數也以二進制形式表示，打到第二條紙帶上。同步讀兩條紙帶，將其數值 模2相加，產生一條相應的密文紙帶。接收端有同樣的密碼比特流，將密文與密碼比特流再 模2相加就得到明文。參閱Vigen'ere cipher。