In cryptography, suggestions for the criteria of secure systems proposed by Shannon in the 1940s: (a)the amount of secrecy offered; (b)the size of the key; (c) the simplicity of enciphering and deciphering operations; (d)the propagation of errors; and (e) extension of the message.; 在密碼學(xué)中,由香農(nóng)于20世紀(jì)40年代提出的安全系統(tǒng)的準(zhǔn)則: (1) 保密的程度; (2) 密鑰的大小;(3) 加密、解密操作的簡(jiǎn)單程度;(4) 差錯(cuò)傳播;(5) 信息的擴(kuò)充量。