在Python中实现RC4

import array

class RC4:
    def __init__(self, key):
        self.S = list(range(256))
        self.key = array.array('B', key)
        self.key_len = len(self.key)
        self.j = 0

    def KSA(self):
        j = 0
        for i in range(256):
            j = (j + self.S[i] + self.key[i % self.key_len]) % 256
            self.S[i], self.S[j] = self.S[j], self.S[i]

    def PRGA(self):
        i = 0
        j = 0
        while True:
            i = (i + 1) % 256
            j = (j + self.S[i]) % 256
            self.S[i], self.S[j] = self.S[j], self.S[i]
            yield self.S[(self.S[i] + self.S[j]) % 256]

    def encrypt(self, plaintext):
        keystream = self.PRGA()
        ciphertext = array.array('B', plaintext)
        for i in range(len(ciphertext)):
            ciphertext[i] ^= next(keystream)
        return ciphertext.tostring()

    def decrypt(self, ciphertext):
        return self.encrypt(ciphertext)

key = b'your_key'
plaintext = b'your_plaintext'

rc4 = RC4(key)
ciphertext = rc4.encrypt(plaintext)
decrypted_text = rc4.decrypt(ciphertext)

print("Ciphertext:", ciphertext)
print("Decrypted Text:", decrypted_text)