组成（AES-128）
秘钥一般由128位（16字节）字符串作为初始秘钥
流程
秘钥与明文异或
先用明文与key进行异或，异或后的结果用于后续加密
轮操作
字节替代
通过S-box进行索引替换
行移位
第一行不变，第二行左移 1 字节，第三行左移 2 字节，第四行左移 3 字节
列混淆
将密文矩阵每一行与一个4x4的常数矩阵进行相乘（有限域乘法）
例如这样的
有限域乘法：例如有一个0x83与0x33相乘
将两者拆成八位二进制，然后一个乘数根据另一个乘数的二进制位是否为0或者1来进行移位操作，最后将所有值进行异或，结果不超过0xff
用以下代码可以实现
def gf_mult(a, b, mod=0x11B):
# 初始结果
result = 0
for i in range(8):
if (b & 1): # 如果 b 的最低位是 1
result ^= a # 将 a 加到结果中（加法是按位异或）
# 左移 a，右移 b
a <<= 1
if a & 0x100: # 如果 a 超过了 8 位，模 mod（0x11B）
a ^= mod # x^8 + x^4 + x^3 + x + 1 的多项式
b >>= 1 # b 右移
return result
# 测试
a = 0x57 # 87 in decimal
b = 0x83 # 131 in decimal
result = gf_mult(a, b)
print(f"Result of {hex(a)} * {hex(b)} = {hex(result)}")
密钥扩展
先将秘钥拆成4组，每组四字节(W1,W2,W3,W3)
将W3进行s-box替换，将替换的结果与轮常量异或（通常是0x01,0x02...)
得到的结果就是第一次扩展的第一次四字节数(W4)
然后将W4 ^ W1 = W5
W5 ^ W2 = W6
W6 ^ W3 = W7
秘钥与明文异或
将秘钥再次与加密的结果异或，进行下一轮
加密和解密脚本
class AES:
MIX_C = [[0x2, 0x3, 0x1, 0x1], [0x1, 0x2, 0x3, 0x1], [0x1, 0x1, 0x2, 0x3], [0x3, 0x1, 0x1, 0x2]]
I_MIXC = [[0xe, 0xb, 0xd, 0x9], [0x9, 0xe, 0xb, 0xd], [0xd, 0x9, 0xe, 0xb], [0xb, 0xd, 0x9, 0xe]]
RCon = [0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000, 0x20000000, 0x40000000, 0x80000000, 0x1B000000, 0x36000000]
S_BOX = [[0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76],
[0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0],
[0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15],
[0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75],
[0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84],
[0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF],
[0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8],
[0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2],
[0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73],
[0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB],
[0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79],
[0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08],
[0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A],
[0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E],
[0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF],
[0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16]]
I_SBOX = [[0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB],
[0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB],
[0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E],
[0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25],
[0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92],
[0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84],
[0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06],
[0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B],
[0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73],
[0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E],
[0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B],
[0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4],
[0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F],
[0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF],
[0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61],
[0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D]]
def SubBytes(self, State):
# 字节替换
return [self.S_BOX[i][j] for i, j in
[(_ >> 4, _ & 0xF) for _ in State]]
def SubBytes_Inv(self, State):
# 字节逆替换
return [self.I_SBOX[i][j] for i, j in
[(_ >> 4, _ & 0xF) for _ in State]]
def ShiftRows(self, S):
# 行移位
return [S[ 0], S[ 5], S[10], S[15],
S[ 4], S[ 9], S[14], S[ 3],
S[ 8], S[13], S[ 2], S[ 7],
S[12], S[ 1], S[ 6], S[11]]
def ShiftRows_Inv(self, S):
# 逆行移位
return [S[ 0], S[13], S[10], S[ 7],
S[ 4], S[ 1], S[14], S[11],
S[ 8], S[ 5], S[ 2], S[15],
S[12], S[ 9], S[ 6], S[ 3]]
def MixColumns(self, State):
# 列混合
return self.Matrix_Mul(self.MIX_C, State)
def MixColumns_Inv(self, State):
# 逆列混合
return self.Matrix_Mul(self.I_MIXC, State)
def RotWord(self, _4byte_block):
# 用于生成轮密钥的字移位
return ((_4byte_block & 0xffffff) << 8) + (_4byte_block >> 24)
def SubWord(self, _4byte_block):
# 用于生成密钥的字节替换
result = 0
for position in range(4):
i = _4byte_block >> position * 8 + 4 & 0xf
j = _4byte_block >> position * 8 & 0xf
result ^= self.S_BOX[i][j] << position * 8
return result
def mod(self, poly, mod = 0b100011011):
# poly模多项式mod
while poly.bit_length() > 8:
poly ^= mod << poly.bit_length() - 9
return poly
def mul(self, poly1, poly2):
# 多项式相乘
result = 0
for index in range(poly2.bit_length()):
if poly2 & 1 << index:
result ^= poly1 << index
return result
def Matrix_Mul(self, M1, M2): # M1 = MIX_C M2 = State
# 用于列混合的矩阵相乘
M = [0] * 16
for row in range(4):
for col in range(4):
for Round in range(4):
M[row + col*4] ^= self.mul(M1[row][Round], M2[Round+col*4])
M[row + col*4] = self.mod(M[row + col*4])
return M
def round_key_generator(self, _16bytes_key):
# 轮密钥产生
w = [_16bytes_key >> 96,
_16bytes_key >> 64 & 0xFFFFFFFF,
_16bytes_key >> 32 & 0xFFFFFFFF,
_16bytes_key & 0xFFFFFFFF] + [0]*40
for i in range(4, 44):
temp = w[i-1]
if not i % 4:
temp = self.SubWord(self.RotWord(temp)) ^ self.RCon[i//4-1]
w[i] = w[i-4] ^ temp
return [self.num_2_16bytes(
sum([w[4 * i] << 96, w[4*i+1] << 64,
w[4*i+2] << 32, w[4*i+3]])
) for i in range(11)]
def AddRoundKey(self, State, RoundKeys, index):
# 异或轮密钥
return self._16bytes_xor(State, RoundKeys[index])
def _16bytes_xor(self, _16bytes_1, _16bytes_2):
return [_16bytes_1[i] ^ _16bytes_2[i] for i in range(16)]
def _16bytes2num(cls, _16bytes):
# 16字节转数字
return int.from_bytes(_16bytes, byteorder = 'big')
def num_2_16bytes(cls, num):
# 数字转16字节
return num.to_bytes(16, byteorder = 'big')
def aes_encrypt(self, plaintext_list, RoundKeys):
State = plaintext_list
State = self.AddRoundKey(State, RoundKeys, 0)
for Round in range(1, 10):
State = self.SubBytes(State)
State = self.ShiftRows(State)
State = self.MixColumns(State)
State = self.AddRoundKey(State, RoundKeys, Round)
State = self.SubBytes(State)
State = self.ShiftRows(State)
State = self.AddRoundKey(State, RoundKeys, 10)
return State
def aes_decrypt(self, ciphertext_list, RoundKeys):
State = ciphertext_list
State = self.AddRoundKey(State, RoundKeys, 10)
for Round in range(1, 10):
State = self.ShiftRows_Inv(State)
State = self.SubBytes_Inv(State)
State = self.AddRoundKey(State, RoundKeys, 10-Round)
State = self.MixColumns_Inv(State)
State = self.ShiftRows_Inv(State)
State = self.SubBytes_Inv(State)
State = self.AddRoundKey(State, RoundKeys, 0)
return State
if __name__ == '__main__':
aes = AES()
key = 0x000102030405060708090a0b0c0d0e0f
RoundKeys = aes.round_key_generator(key)
# 加密
plaintext = 0x00112233445566778899aabbccddeeff
# 0x00112233445566778899aabbccddeeff -> b'\x00\x11"3DUfw\x88\x99\xaa\xbb\xcc\xdd\xee\xff'
plaintext = aes.num_2_16bytes(plaintext)
ciphertext = aes.aes_encrypt(plaintext, RoundKeys)
print('ciphertext = ' + hex(aes._16bytes2num(ciphertext)))
# 解密
ciphertext = 0x69c4e0d86a7b0430d8cdb78070b4c55a
ciphertext = aes.num_2_16bytes(ciphertext)
plaintext = aes.aes_decrypt(ciphertext, RoundKeys)
print('plaintext = ' + hex(aes._16bytes2num(plaintext)))
摘自https://blog.csdn.net/weixin_42580862/article/details/101703941