58 lines
1.6 KiB
Python
58 lines
1.6 KiB
Python
#!/usr/bin/env python3
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"""
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凯撒加密算法示例
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一个教学用的凯撒密码实现
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"""
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def caesar_encrypt(plaintext, shift):
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"""凯撒加密函数"""
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ciphertext = ""
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for char in plaintext:
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if char.isalpha():
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base = ord('A') if char.isupper() else ord('a')
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new_char = chr((ord(char) - base + shift) % 26 + base)
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ciphertext += new_char
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else:
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ciphertext += char
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return ciphertext
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def caesar_decrypt(ciphertext, shift):
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"""凯撒解密函数"""
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return caesar_encrypt(ciphertext, -shift)
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def main():
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"""主函数，用户交互界面"""
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print("凯撒密码示例")
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while True:
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print("\n1.加密\n2.解密\n3.退出")
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choice = input("选择: ").strip()
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if choice == "1":
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text = input("明文: ")
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try:
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shift = int(input("移位值: "))
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result = caesar_encrypt(text, shift)
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print(f"密文: {result}")
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except ValueError:
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print("移位值必须是整数!")
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elif choice == "2":
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text = input("密文: ")
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try:
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shift = int(input("移位值: "))
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result = caesar_decrypt(text, shift)
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print(f"明文: {result}")
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except ValueError:
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print("移位值必须是整数!")
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elif choice == "3":
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print("再见!")
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break
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else:
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print("无效选择")
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if __name__ == "__main__":
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main() |