def break_ecb(oracle: Callable[[bytes], bytes]) -> bytes:
bs = blocksize(oracle)
l = len(oracle(b""))
prefix_length = len_prefix(oracle)
string_length = len_string(oracle) - prefix_length
plaintext = b""
uc = (l + bs - prefix_length - 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])
break
return de_pkcs7(plaintext)
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)
def len_string(oracle):
l = len(oracle())
bs = blocksize(oracle)
for i in range(1, bs + 1):
if l < len(oracle(i * b'A')):
return l - i - len_prefix(oracle)
