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class RC4:
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    def __init__(self, key):
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        """用给定密钥初始化RC4"""
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        self.S = list(range(256))
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        self.i = 0
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        self.j = 0
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        self._ksa(key)
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    def _ksa(self, key):
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        """密钥调度算法"""
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        j = 0
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        key_length = len(key)
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        for i in range(256):
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            j = (j + self.S[i] + key[i % key_length]) % 256
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            self.S[i], self.S[j] = self.S[j], self.S[i]
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    def _prga(self):
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        """伪随机生成算法（生成一个字节）"""
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        self.i = (self.i + 1) % 256
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        self.j = (self.j + self.S[self.i]) % 256
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        self.S[self.i], self.S[self.j] = self.S[self.j], self.S[self.i]
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        t = (self.S[self.i] + self.S[self.j]) % 256
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        return self.S[t]
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    def process(self, data):
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        """加密或解密数据"""
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        result = bytearray()
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        for byte in data:
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            key_byte = self._prga()
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            result.append(byte ^ key_byte)
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        return bytes(result)
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def rc4_main():
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    # 测试数据
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    key = b"secret"
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    plaintext = b"password"
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    print(f"密钥: {key.hex()}")
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    print(f"明文: {plaintext.hex()}")
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    # 加密
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    rc4 = RC4(key)
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    ciphertext = rc4.process(plaintext)
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    print(f"密文: {ciphertext.hex()}")
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    # 解密（使用相同密钥重新初始化）
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    rc4_decrypt = RC4(key)
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    decrypted = rc4_decrypt.process(ciphertext)
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    print(f"解密: {decrypted.hex()}")
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    print(f"验证: {decrypted == plaintext}")
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if __name__ == "__main__":
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    rc4_main()