python实现RC6加密算法
时间: 2023-11-10 10:03:30 浏览: 58
以下是Python实现RC6加密算法的代码:
```python
def rotate_left(n, d):
return ((n << d) | (n >> (32 - d))) & 0xFFFFFFFF
def rotate_right(n, d):
return ((n >> d) | (n << (32 - d))) & 0xFFFFFFFF
def expand_key(key, word_size=32, rounds=20):
c = len(key) // (word_size // 8)
L = [key[i:i+4] for i in range(0, len(key), 4)]
P = 0xB7E15163
Q = 0x9E3779B9
K = [0] * (2 * rounds + 4)
K[0] = P
for i in range(1, 2 * rounds + 4):
K[i] = (K[i-1] + Q) & 0xFFFFFFFF
A = B = i = j = 0
v = 3 * max(c, (2 * rounds + 4))
for s in range(v):
A = K[i] = rotate_left((K[i] + A + B) & 0xFFFFFFFF, 3)
B = L[j] = rotate_left((L[j] + A + B) & 0xFFFFFFFF, (A + B) & 0x1F)
i = (i + 1) % (2 * rounds + 4)
j = (j + 1) % c
return K
def encrypt_block(M, K, word_size=32, rounds=20):
A = int.from_bytes(M[:4], byteorder='little')
B = int.from_bytes(M[4:], byteorder='little')
P = 0xB7E15163
Q = 0x9E3779B9
for i in range(1, rounds + 1):
t = rotate_left((B * (2 * B + 1)) & 0xFFFFFFFF, int(math.log(word_size, 2)))
u = rotate_left((A * (2 * A + 1)) & 0xFFFFFFFF, int(math.log(word_size, 2)))
A = rotate_left((A ^ t) & 0xFFFFFFFF, u % word_size) + K[2*i-1]
B = rotate_left((B ^ u) & 0xFFFFFFFF, t % word_size) + K[2*i]
A = (A + K[2*rounds+1]) & 0xFFFFFFFF
B = (B + K[2*rounds+2]) & 0xFFFFFFFF
return A.to_bytes(4, byteorder='little') + B.to_bytes(4, byteorder='little')
def encrypt(plaintext, key, word_size=32, rounds=20):
ciphertext = b''
K = expand_key(key, word_size=word_size, rounds=rounds)
for i in range(0, len(plaintext), 8):
block = plaintext[i:i+8]
ciphertext += encrypt_block(block, K, word_size=word_size, rounds=rounds)
return ciphertext
# Example usage
plaintext = b'Hello, world!'
key = b'This is a key.'
ciphertext = encrypt(plaintext, key)
print(ciphertext)
```