def repeating_key_loop(key):
"""generates the next byte of key information for repeating key XOR."""
loc = 0
while(True):
h = crypt_utils.toHex(key[loc])
yield h
loc = (loc + 1) % len(key)
def base64_to_hex(b64):
if type(b64) != str and type(b64) != bytes:
raise TypeError("Error: base64_to_hex requires input in str")
if type(b64) is not bytes:
b64 = bytes(b64, 'UTF8')
h = base64.standard_b64decode(b64)
return crypt_utils.toHex(h)
def crack_vigenere(cyphertext):
if not crypt_utils.is_hex(cyphertext):
cyphertext = crypt_utils.toHex(cyphertext)
keysizes = generate_vigenere_key_sizes(cyphertext)
options = {}
for keysize in keysizes:
blocks = vigenere_blocks(cyphertext, keysize)
try:
# Chunk the hex strings into 8 bit lengths (2 Hex digits)
# Otherwise transpose would split bytes incorrectly
blocks = [[s[i] + s[i+1] for i in range(0, len(s), 2)] for s in blocks]
except IndexError:
# blocks contain invalid Hex, so assume this is not the solution
continue
blocks = vigenere_transpose(blocks)
decrypted_message = []
key = ''
for block in blocks:
key_byte, message_part = search_single_byte_xor_key(block)
decrypted_message.append(message_part)
key += key_byte
decrypted_message = vigenere_transpose(decrypted_message)
decrypted_message = ''.join(decrypted_message)
score = score_char_freq(decrypted_message)
try:
key = binascii.unhexlify(key).decode('ascii')
except:
#if key cannot be converted to ascii, leave as is
pass
options[score] = (key, decrypted_message)
return options[min(options)]
