本文人工撰写；生成式AI仅用于校对和手写公式转 LaTeX。
题目附件ez_aes.py:
from secret import flag
rc = [0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78, 0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef,0xf1]
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]
]
s_box_inv = [
[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 sub_bytes(grid):
for i, v in enumerate(grid):
grid[i] = s_box[v >> 4][v & 0xf]
def shift_rows(grid):
for i in range(4):
grid[i::4] = grid[i::4][i:] + grid[i::4][:i]
grid =grid[0::4]+grid[1::4]+grid[2::4]+grid[3::4]
def mix_columns(grid):
def mul_by_2(n):
s = (n << 1) & 0xff
if n & 128:
s ^= 0x1b
return s
def mul_by_3(n):
return n ^ mul_by_2(n)
def mix_column(c):
return [
mul_by_2(c[0]) ^ mul_by_3(c[1]) ^ c[2] ^ c[3], # [2 3 1 1]
c[0] ^ mul_by_2(c[1]) ^ mul_by_3(c[2]) ^ c[3], # [1 2 3 1]
c[0] ^ c[1] ^ mul_by_2(c[2]) ^ mul_by_3(c[3]), # [1 1 2 3]
mul_by_3(c[0]) ^ c[1] ^ c[2] ^ mul_by_2(c[3]), # [3 1 1 2]
]
for i in range(0, 16, 4):
grid[i:i + 4] = mix_column(grid[i:i + 4])
def key_expansion(grid):
for i in range(10 * 4):
r = grid[-4:]
if i % 4 == 0: # 对上一轮最后4字节自循环、S-box置换、轮常数异或，从而计算出当前新一轮最前4字节
for j, v in enumerate(r[1:] + r[:1]):
r[j] = s_box[v >> 4][v & 0xf] ^ (rc[i // 4] if j == 0 else 0)
for j in range(4):
grid.append(grid[-16] ^ r[j])
return grid
def add_round_key(grid, round_key):
for i in range(16):
grid[i] ^= round_key[i]
def encrypt(b, expanded_key):
# First round
add_round_key(b, expanded_key)
for i in range(1, 10):
sub_bytes(b)
shift_rows(b)
mix_columns(b)
add_round_key(b, expanded_key[i * 16:])
# Final round
sub_bytes(b)
shift_rows(b)
add_round_key(b, expanded_key[-16:])
return b
def aes(key, msg):
expanded = key_expansion(bytearray(key))
# Pad the message to a multiple of 16 bytes
b = bytearray(msg + b'\x00' * (16 - len(msg) % 16))
# Encrypt the message
for i in range(0, len(b), 16):
b[i:i + 16] = encrypt(b[i:i + 16], expanded)
return bytes(b)
if __name__ == '__main__':
key = b'Slightly different from the AES.'
enc = aes(key, flag)
print('Encrypted:', enc)
#Encrypted: b'%\x98\x10\x8b\x93O\xc7\xf02F\xae\xedA\x96\x1b\xf9\x9d\x96\xcb\x8bT\r\xd31P\xe6\x1a\xa1j\x0c\xe6\xc8'
注意到Rcon和ShiftRows为非标过程，但仍保持可逆，所以需要我们手写解密过程:(。
脚本如下:
rc = [0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78, 0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef,0xf1]
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]
]
s_box_inv = [
[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 sub_bytes(grid):
for i, v in enumerate(grid):
grid[i] = s_box[v >> 4][v & 0xf]
def add_bytes(grid):
for i, v in enumerate(grid):
grid[i] = s_box_inv[v >> 4][v & 0xf]
def shift_rows(grid): <---这里实际啥也没干，神奇的python
for i in range(4):
grid[i::4] = grid[i::4][i:] + grid[i::4][:i]
grid =grid[0::4]+grid[1::4]+grid[2::4]+grid[3::4]
def rev_shift_rows(grid):
0x3f
def mix_columns(grid):
def mul_by_2(n):
s = (n << 1) & 0xff
if n & 128:
s ^= 0x1b
return s
def mul_by_3(n):
return n ^ mul_by_2(n)
def mix_column(c):
return [
mul_by_2(c[0]) ^ mul_by_3(c[1]) ^ c[2] ^ c[3], # [2 3 1 1]
c[0] ^ mul_by_2(c[1]) ^ mul_by_3(c[2]) ^ c[3], # [1 2 3 1]
c[0] ^ c[1] ^ mul_by_2(c[2]) ^ mul_by_3(c[3]), # [1 1 2 3]
mul_by_3(c[0]) ^ c[1] ^ c[2] ^ mul_by_2(c[3]), # [3 1 1 2]
]
for i in range(0, 16, 4):
grid[i:i + 4] = mix_column(grid[i:i + 4])
def rev_mix_columns(grid):
def mul_by_2(n):
s = (n << 1) & 0xff
if n & 128:
s ^= 0x1b
return s
def mul_by_n(a, b):
res = 0
while(b):
if(b & 1):
res ^= a
a = mul_by_2(a)
b >>= 1
return res
def mix_column(c):
return [
mul_by_n(c[0], 0x0e) ^ mul_by_n(c[1], 0x0b) ^ mul_by_n(c[2], 0x0d) ^ mul_by_n(c[3], 0x09),
mul_by_n(c[0], 0x09) ^ mul_by_n(c[1], 0x0e) ^ mul_by_n(c[2], 0x0b) ^ mul_by_n(c[3], 0x0d),
mul_by_n(c[0], 0x0d) ^ mul_by_n(c[1], 0x09) ^ mul_by_n(c[2], 0x0e) ^ mul_by_n(c[3], 0x0b),
mul_by_n(c[0], 0x0b) ^ mul_by_n(c[1], 0x0d) ^ mul_by_n(c[2], 0x09) ^ mul_by_n(c[3], 0x0e),
]
for i in range(0, 16, 4):
grid[i:i + 4] = mix_column(grid[i:i + 4])
def key_expansion(grid):
for i in range(10 * 4):
r = grid[-4:]
if i % 4 == 0: # 对上一轮最后4字节自循环、S-box置换、轮常数异或，从而计算出当前新一轮最前4字节
for j, v in enumerate(r[1:] + r[:1]):
r[j] = s_box[v >> 4][v & 0xf] ^ (rc[i // 4] if j == 0 else 0)
for j in range(4):
grid.append(grid[-16] ^ r[j])
return grid
def add_round_key(grid, round_key):
for i in range(16):
grid[i] ^= round_key[i]
def encrypt(b, expanded_key):
# First round
add_round_key(b, expanded_key)
for i in range(1, 10):
sub_bytes(b)
shift_rows(b)
mix_columns(b)
add_round_key(b, expanded_key[i * 16:])
# Final round
sub_bytes(b)
shift_rows(b)
add_round_key(b, expanded_key[-16:])
return b
def dncrypt(b, expanded_key):
# First round
add_round_key(b, expanded_key[-16:])
rev_shift_rows(b)
add_bytes(b)
for i in range(9, 0, -1):
add_round_key(b, expanded_key[i * 16:])
rev_mix_columns(b)
rev_shift_rows(b)
add_bytes(b)
# Final round
add_round_key(b, expanded_key)
return b
def aes(key, msg):
expanded = key_expansion(bytearray(key))
# Pad the message to a multiple of 16 bytes
b = bytearray(msg + b'\x00' * (16 - len(msg) % 16))
# Encrypt the message
for i in range(0, len(b), 16):
b[i:i + 16] = encrypt(b[i:i + 16], expanded)
return bytes(b)
def rev_aes(key, msg):
expanded = key_expansion(bytearray(key))
print(">>>", expanded)
# Pad the message to a multiple of 16 bytes
b = bytearray(msg)
# Encrypt the message
for i in range(0, len(b), 16):
b[i:i + 16] = dncrypt(b[i:i + 16], expanded)
return bytes(b)
if __name__ == '__main__':
key = b'Slightly different from the AES.'
flag = b"123123"
res = b'%\x98\x10\x8b\x93O\xc7\xf02F\xae\xedA\x96\x1b\xf9\x9d\x96\xcb\x8bT\r\xd31P\xe6\x1a\xa1j\x0c\xe6\xc8'
enc = rev_aes(key, res)
print('Dncrypted:', enc)
#Encrypted: b'%\x98\x10\x8b\x93O\xc7\xf02F\xae\xedA\x96\x1b\xf9\x9d\x96\xcb\x8bT\r\xd31P\xe6\x1a\xa1j\x0c\xe6\xc8'
输出:
>>> bytearray(b"Slightly different from the AES.\x12\x99\x11\xe5`\xf6|\xc5\x14\x9e\x19\xe5U\xdbJ\xcb\x88O\x0e\x19\xe8\xb9r\xdc\xfc\'k9\xa9\xfc!\xf2\x0c\xb2\x87\xca\xe4\x0b\xf5\x16\x18,\x9e/\xb1\xd0\xbf\xdd9\xbaF\x02\xdd\xb1\xb3\x14\xc5\x9d-;tM\x92\
xe6\x8c\xf5\xc8\x90QD{\x84\x94\xd9V\xbf\xe0\x94\xc4Y\xc9\xe9\x03q\x98\xadx\xf5\x0ct.J\xec\xe0\xea\x13Pn~\xbf\xc8\xc3\x06J\xc4\xb7(\x00(W\xc2\x13\x82K\x03\x8bJ\x88\x05\xc1\x8e?-\xc1\xa6h\xef\xd2]\x94\xb6\xaf\x17\x1c\xb3n\x99#\x9e\xaf?Kq}E7I\xdaR+\xf
a\xb4\xcb\x08d\x1b\xf4C\x15f")
Dncrypted: b'moectf{THIS_IS_FLAG}\x00'