def break_ecb(oracle):
bs = blocksize(oracle)
l = len(oracle())
string_length = len_string(oracle)
plaintext = b''
prefix = (l + bs - 1) * b'A'
while len(plaintext) <= string_length:
oracle_prefix = oracle(prefix)
for i in range(127):
test = prefix + plaintext + bytes([i])
if oracle(test)[l:l + bs] == oracle_prefix[l:l + bs]:
#if i < 10: # hack to break if non-
# return plaintext # printable padding found
prefix = prefix[1:]
plaintext += bytes([i])
#print(chr(i), end = "", flush = True)
break
return de_pkcs7(plaintext)
if __name__ == "__main__":
if not detect_ecb(oracle(64 * b'A')):
print("Not ECB")
raise SystemExit
print(break_ecb(oracle).decode())
bs = blocksize(oracle)
for i in range(1, bs + 1):
if l < len(oracle(i * b'A')):
return l - i - len_prefix(oracle)
def break_ecb(oracle):
bs = blocksize(oracle)
l = len(oracle())
string_length = len_string(oracle)
prefix_length = len_prefix(oracle)
plaintext = b''
uc = (l + bs - len_prefix(oracle) - 1) * b'A'
while len(plaintext) <= string_length:
oracle_input = oracle(uc)
for i in range(127):
test = uc + plaintext + bytes([i])
if oracle(test)[l:l + bs] == oracle_input[l:l + bs]:
uc = uc[1:]
plaintext += bytes([i])
#print(chr(i), end = "", flush = True)
break
return de_pkcs7(plaintext)
if __name__ == "__main__":
assert detect_ecb(oracle(48 * b'A')), "Not ECB"
print(break_ecb(oracle).decode())
def main() -> None:
if not detect_ecb(oracle(64 * b"A")):
print("Not ECB")
raise SystemExit
print(break_ecb(oracle).decode())
def main() -> None:
assert detect_ecb(oracle(48 * b"A")), "Not ECB"
print(break_ecb(oracle).decode())
