aes算法实现
时间: 2023-07-25 20:10:14 浏览: 37
AES(Advanced Encryption Standard)算法是一种对称加密算法,用于数据加密和解密。下面是AES算法的简单实现:
1. 字节代替(SubBytes):将每个字节替换成一个S盒中对应的字节。
```
def sub_bytes(state):
for i in range(4):
for j in range(4):
state[i][j] = S_BOX[state[i][j]]
return state
```
2. 行移位(ShiftRows):将每一行循环左移若干位。
```
def shift_rows(state):
for i in range(4):
state[i] = left_shift(state[i], i)
return state
def left_shift(row, n):
return row[n:] + row[:n]
```
3. 列混淆(MixColumns):将每一列进行线性变换。
```
def mix_columns(state):
for i in range(4):
column = [state[j][i] for j in range(4)]
new_column = mix_column(column)
for j in range(4):
state[j][i] = new_column[j]
return state
def mix_column(column):
new_column = []
for i in range(4):
a = column[i]
b = column[(i+1)%4]
c = column[(i+2)%4]
d = column[(i+3)%4]
new_column.append(multiply(a, 2) ^ multiply(b, 3) ^ multiply(c, 1) ^ multiply(d, 1))
return new_column
def multiply(a, b):
if b == 1:
return a
elif b == 2:
return multiply_by_2(a)
elif b == 3:
return multiply_by_3(a)
def multiply_by_2(a):
if a < 0x80:
return a << 1
else:
return (a << 1) ^ 0x1b
def multiply_by_3(a):
return multiply_by_2(a) ^ a
```
4. 密钥加(AddRoundKey):将当前状态和密钥进行异或运算。
```
def add_round_key(state, round_key):
for i in range(4):
for j in range(4):
state[i][j] ^= round_key[i][j]
return state
```
以上是AES算法的基本步骤,实现时需要根据具体情况进行组织和调用。