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.; 在密码学中，于1917年为印刷电报开发的一种早期序列密码。明文字母按二进制编码，打到 纸带上；一组随机数也以二进制形式表示，打到第二条纸带上。同步读两条纸带，将其数值 模2相加，产生一条相应的密文纸带。接收端有同样的密码比特流，将密文与密码比特流再 模2相加就得到明文。参阅Vigen'ere cipher。