def aes_cbc_decrypt(ciphertext, key, iv):
blocks = [ciphertext[i:i + 16] for i in range(0, len(ciphertext), 16)]
plaintext = b""
for block in blocks:
deciphered = aes_ecb_decrypt(block, key)
plain_block = xor_repeating_key(deciphered, iv)
iv = block
plaintext += plain_block
return plaintext
def aes_cbc_encrypt(plaintext, key, iv):
blocks = [plaintext[i:i + 16] for i in range(0, len(plaintext), 16)]
ciphertext = b""
for block in blocks:
xored_block = xor_repeating_key(block, iv)
ciphered = aes_ecb_encrypt(xored_block, key)
iv = ciphered
ciphertext += ciphered
return ciphertext
def decode_hex(inputStr):
bestStr = ""
bestScore = 0
thisStr = xor_repeating_key(inputStr)
if score(thisStr) > bestScore:
bestScore = score(thisStr)
bestStr = thisStr
return "Plaintext: {}".format(bestStr)
#!/usr/bin/env python3
import sys
import binascii
sys.path.append('..')
from helpers import abort
from xor import xor_repeating_key
if __name__ == "__main__":
if len(sys.argv) == 3:
with open(sys.argv[1]) as input_file:
line = input_file.readline().rstrip()
print(
str(
binascii.hexlify(
xor_repeating_key(line, sys.argv[2].encode())),
'ascii'))
else:
abort(f'{sys.argv[0]}: filename key')
from xor import xor_repeating_key
msg = """Burning 'em, if you ain't quick and nimble
I go crazy when I hear a cymbal""".encode('ascii')
key = "ICE".encode('ascii')
xored = xor_repeating_key(msg, key)
print(xored.hex())
expected = ("0b3637272a2b2e63622c2e69692a23693a2a3c6324202d623d63343c2a262263"
"24272765272a282b2f20430a652e2c652a3124333a653e2b2027630c692b2028"
"3165286326302e27282f")
assert(xored.hex() == expected)
from distance import hamming
from base64 import b64decode
from xor import (xor_single_char_key, xor_repeating_key,
break_xor_repeating_key, guess_key_lengths)
from frequency import english_test
with open("06.txt") as f:
lines = f.readlines()
cipher = b64decode(''.join(lines))
key_length = guess_key_lengths(cipher)[0]
print("guessed key length: %i" % key_length)
key = break_xor_repeating_key(cipher, key_length)
print("key: %s" % key.decode('ascii'))
decrypted = xor_repeating_key(cipher, key)
message = decrypted.decode('ascii')
print(message)
assert(message.startswith("I'm back and I'm ringin' the bell"))