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executable file 174 lines (141 sloc) 5.17 KB
#!/usr/bin/env python3
import sys
import binascii
import itertools
import collections
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
]
# shift row permutation on indexes
shift_rows = [
0, 13, 10, 7,
4, 1, 14, 11,
8, 5, 2, 15,
12, 9, 6, 3,
]
# indexes for every column
cols = [
(0, 1, 2, 3),
(4, 5, 6, 7),
(8, 9, 10, 11),
(12, 13, 14, 15)
]
def inv_perm(perm):
inv = [0] * len(perm)
for i in range(len(perm)):
inv[perm[i]] = i
return inv
sboxI = inv_perm(sbox)
def mult(a, b):
assert 0x100 > a >= 0
assert 0x100 > b >= 0
r = 0
p = 0b100011011
while b:
if b & 1:
r ^= a
a <<= 1
b >>= 1
if a >> 8:
a ^= p
return r
def mix_column(v):
assert len(v) == 4
r1 = mult(2, v[0]) ^ mult(3, v[1]) ^ v[2] ^ v[3]
r2 = v[0] ^ mult(2, v[1]) ^ mult(3, v[2]) ^ v[3]
r3 = v[0] ^ v[1] ^ mult(2, v[2]) ^ mult(3, v[3])
r4 = mult(3, v[0]) ^ v[1] ^ v[2] ^ mult(2, v[3])
return (r1, r2, r3, r4)
def mix_fault(d, row):
col = [0, 0, 0, 0]
col[row] = d
return mix_column(col)
Ds = []
for row in range(4):
for d in range(1, 0x100):
Ds.append(mix_fault(d, row))
def recover(ct_correct, ct_fault, I, K):
assert len(I) == 4
assert len(ct_correct) == len(ct_fault) == 16
def solve(xA, xB, D):
ks = []
for k in range(0x100):
if D == sboxI[xA ^ k] ^ sboxI[xB ^ k]:
ks.append(k)
assert len(ks) in (0, 2, 4)
return ks
for D in Ds:
# calculate candiates for each byte
ks = [[], [], [], []]
for j, i in enumerate(I):
ks[j] = solve(ct_correct[i], ct_fault[i], D[j])
if len(ks[j]) == 0:
break
# expand the cross product to get full 32-bit keys
for k in itertools.product(*ks):
K[k] += 1
def diff(s1, s2):
idx = set([])
for i in range(len(s1)):
if s1[i] != s2[i]:
idx.add(i)
return frozenset(idx)
if __name__ == '__main__':
# sample file
with open(sys.argv[1], 'r') as f:
samples = map(str.strip, f.readlines())
samples = [binascii.unhexlify(s) for s in samples]
# correct ciphertext
correct = binascii.unhexlify(sys.argv[2])
# optional threshold
try:
threshold = int(sys.argv[3])
except IndexError:
threshold = None
# group ciphertext by faulty indexes
Is = [tuple([shift_rows[v] for v in col]) for col in cols]
groups = { I: [] for I in Is}
for sample in samples:
df = diff(sample, correct)
for I in Is:
if all([i in df for i in I]):
groups[I].append(sample)
# extract from every group of faulty indexes
KEY = [None] * 16
for I in Is:
print('I : %14s, ciphertexts: %d' % (I, len(groups[I])))
# find the most seen 32-bit key candidates
K = collections.Counter()
for i, sample in enumerate(groups[I]):
recover(correct, sample, I, K)
# print status
show = ''.join(['%02x' % v if v else '??' for v in KEY])
print('Key: %s, Sample %d / %d, Cand: %d, Top: %s' % (show, i, len(groups[I]), len(K), K.most_common(2)))
# check optional threshold
try:
_, cnt = K.most_common(1)[0]
if cnt >= threshold:
break
except:
pass
# fill in the full round key with the recovered 32-bits
key, _ = K.most_common(1)[0]
for j, i in enumerate(I):
assert KEY[i] is None
KEY[i] = key[j]
print('KEY:', bytes(KEY).hex())