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| from binascii import hexlify, unhexlify
Sbox = [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]
inv_Sbox = [Sbox.index(i) for i in range(0x100)]
def xor(a, b):
return bytes(x ^ y for x, y in zip(a, b))
f = open('ciphertext', 'r')
cipher = unhexlify(f.readline().strip())
prefix_a = []
for i in range(65536):
_ = f.readline().strip().split(' ')
prefix_a.append((_[0], _[1]))
suffix_a = []
for i in range(65536):
_ = f.readline().strip().split(' ')
suffix_a.append((_[0], _[1]))
prefix_a_ct_right, suffix_a_ct_left = set(), set()
prefix_a_ct_back, suffix_a_ct_back = dict(), dict()
for i in range(65536):
prefix_a_ct_right.add(prefix_a[i][1][8:])
prefix_a_ct_back[prefix_a[i][1][8:]] = i
suffix_a_ct_left.add(suffix_a[i][1][:8])
suffix_a_ct_back[suffix_a[i][1][:8]] = i
crash = prefix_a_ct_right & suffix_a_ct_left
pairs = []
for _ in crash:
i, j = prefix_a_ct_back[_], suffix_a_ct_back[_]
pairs.append((prefix_a[i], suffix_a[j]))
for _ in pairs:
print(_)
def func(x, k):
tmp = list(xor(x, k))
tmp = [Sbox[_] for _ in tmp]
_ = tmp[1:] + [0]
for i in range(3):
tmp[i] = (tmp[i] + _[i]) % 0x100
return bytes(tmp)
def inv_func(x, k):
tmp = list(x)
for i in range(2, -1, -1):
tmp[i] = (tmp[i] - tmp[i+1]) % 0x100
tmp = [inv_Sbox[_] for _ in tmp]
return xor(bytes(tmp), k)
def crack_key(pair):
x = xor(unhexlify(pair[0][0][8:]), unhexlify(pair[1][0][:8]))
tmp = list(x)
for i in range(2, -1, -1):
tmp[i] = (tmp[i] - tmp[i + 1]) % 0x100
tmp = [inv_Sbox[_] for _ in tmp]
key1 = xor(bytes(tmp), unhexlify(pair[1][0][8:]))
x = xor(unhexlify(pair[1][1][8:]), unhexlify(pair[0][1][:8]))
tmp = list(x)
for i in range(2, -1, -1):
tmp[i] = (tmp[i] - tmp[i + 1]) % 0x100
tmp = [inv_Sbox[_] for _ in tmp]
key2 = xor(bytes(tmp), unhexlify(pair[0][1][8:]))
if key1 == key2:
return key1
else:
return None
for pair in pairs:
k = crack_key(pair)
if k:
key = k
break
print(key)
def dec_block(x, k):
l, r = x[:4], x[4:]
for i in range(111111):
l, r = r, xor(l, func(r, k))
l, r = r, l
return (l + r)
def dec(x, k):
pt = b''
for i in range(0, len(x), 8):
pt += dec_block(x[i:i+8], k)
return pt
print(dec(cipher, key))
'''
(('61616161c5039c68', 'ac74c268a9084661'), ('29d6d89e61616161', 'a9084661a403759e'))
(('61616161cb9d3d82', 'e2c22abd8cf47ca5'), ('9397d96461616161', '8cf47ca5cb8de97a'))
(('616161614e9c397d', 'a9a59268a5a34a22'), ('de59099b61616161', 'a5a34a22c8c8d126'))
(('616161612ca7387d', '69b59568e8cf6822'), ('7f62089b61616161', 'e8cf6822ed24df26'))
(('616161613f847d04', 'a9eae19288dcb189'), ('4e6a4de261616161', '88dcb1891503e936'))
b'Nb=\x94'
b'flag{beginning_of_cryptanalysis_series_excited}\x01'
'''
|
