简单替换密码是最常用的密码，包括为每个密文文本字符替换每个纯文本字符的算法.在这个过程中，与凯撒密码算法相比，字母表是混乱的.
示例
简单替换密码的密钥通常由26个字母组成.一个示例键是 :
plain alphabet : abcdefghijklmnopqrstuvwxyzcipher alphabet: phqgiumeaylnofdxjkrcvstzwb
使用上述密钥的示例加密是 :
plaintext : defend the east wall of the castleciphertext: giuifg cei iprc tpnn du cei qprcni
以下代码显示了一个实现简单替换密码的程序;
import random, sysLETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'def main(): message = '' if len(sys.argv) > 1: with open(sys.argv[1], 'r') as f: message = f.read() else: message = raw_input("Enter your message: ") mode = raw_input("E for Encrypt, D for Decrypt: ") key = '' while checkKey(key) is False: key = raw_input("Enter 26 ALPHA key (leave blank for random key): ") if key == '': key = getRandomKey() if checkKey(key) is False:print('There is an error in the key or symbol set.') translated = translateMessage(message, key, mode) print('Using key: %s' % (key)) if len(sys.argv) > 1: fileOut = 'enc.' + sys.argv[1] with open(fileOut, 'w') as f: f.write(translated) print('Success! File written to: %s' % (fileOut)) else: print('Result: ' + translated)# Store the key into list, sort it, convert back, compare to alphabet.def checkKey(key): keyString = ''.join(sorted(list(key))) return keyString == LETTERSdef translateMessage(message, key, mode): translated = '' charsA = LETTERS charsB = key # If decrypt mode is detected, swap A and B if mode == 'D': charsA, charsB = charsB, charsA for symbol in message: if symbol.upper() in charsA: symIndex = charsA.find(symbol.upper()) if symbol.isupper(): translated += charsB[symIndex].upper() else: translated += charsB[symIndex].lower()else: translated += symbol return translateddef getRandomKey(): randomList = list(LETTERS) random.shuffle(randomList) return ''.join(randomList)if __name__ == '__main__': main()输出
您可以观察以下内容当你实现上面给出的代码时输出 :
