文章目录

Python基础编程入门实例：恺撒密码

一、什么是恺撒密码

原文：A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
密文：D E F G H I J K L M N O P Q R S T U V W X Y Z A B C

C = ( P + 3 ) mod 26

P = ( C – 3 ) mod 26

二、程序运行环境

程序运行环境是：pycharm2021

三、恺撒密码：加密

3.1、恺撒密码加密实例程序

# 恺撒密码加密
def Caesar_PW_Encryption():
    inputText = input("请输入明文文本: ")
    for index in inputText:
        if "a" <= index <= "z":
            print(chr(ord("a") + (ord(index) - ord("a") + 3) % 26), end='')
        elif "A" <= index <= "Z":
            print(chr(ord("A") + (ord(index) - ord("A") + 3) % 26), end='')
        else:
            print(index, end='')

if __name__ == '__main__':
    # 恺撒密码加密
    Caesar_PW_Encryption()

3.2、恺撒密码加密实例程序运行结果

四、恺撒密码：解密

4.1、恺撒密码解密实例程序

# 恺撒密码解密
def Ceasar_PW_Decryption():
    inputText = input("请输入加密后文本: ")
    for index in inputText:
        if "a" <= index <= "z":
            print(chr(ord("a") + (ord(index) - ord("a") - 3) % 26), end='')
        elif "A" <= index <= "Z":
            print(chr(ord("A") + (ord(index) - ord("A") - 3) % 26), end='')
        else:
            print(index, end='')

if __name__ == '__main__':
    # 恺撒密码加密
    Caesar_PW_Encryption()

    # 恺撒密码解密
    Ceasar_PW_Decryption()

4.2、恺撒密码解密实例程序运行结果

五、完整程序

# 恺撒密码加密
def Caesar_PW_Encryption():
    inputText = input("请输入明文文本: ")
    for index in inputText:
        if "a" <= index <= "z":
            print(chr(ord("a") + (ord(index) - ord("a") + 3) % 26), end='')
        elif "A" <= index <= "Z":
            print(chr(ord("A") + (ord(index) - ord("A") + 3) % 26), end='')
        else:
            print(index, end='')

# 恺撒密码解密
def Ceasar_PW_Decryption():
    inputText = input("请输入加密后文本: ")
    for index in inputText:
        if "a" <= index <= "z":
            print(chr(ord("a") + (ord(index) - ord("a") - 3) % 26), end='')
        elif "A" <= index <= "Z":
            print(chr(ord("A") + (ord(index) - ord("A") - 3) % 26), end='')
        else:
            print(index, end='')

if __name__ == '__main__':
    # 恺撒密码加密
    Caesar_PW_Encryption()

    # 恺撒密码解密
    Ceasar_PW_Decryption()

    

六、总结

本文主要讲解了恺撒密码：采用了替换方法对信息中的每一个英文字符循环替换为字母表序列该字符后面第三个字符。并通过一个实例程序来进一步加强对恺撒密码的理解与运用。

来源：编程爱好者-阿新