43 lines
1.1 KiB
Python
43 lines
1.1 KiB
Python
|
import base64 as b64
|
||
|
|
|
||
|
|
PLAINTEXT = '''{"showpassword":"no","bgcolor":"#ffffff"}'''
|
||
|
|
COOKIE = 'HmYkBwozJw4WNyAAFyB1VUcqOE1JZjUIBis7ABdmbU1GIjEJAyIxTRg='
|
||
|
|
FORGED_PLAINTEXT = '''{"showpassword":"yes","bgcolor":"#ffffff"}'''
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
def xorbytes(x: bytes, y: bytes) -> bytes:
|
||
|
|
Lx, Ly = len(x), len(y)
|
||
|
|
if Lx < Ly: return xorbytes(y, x)
|
||
|
|
|
||
|
|
return bytes(x[i]^y[i%Ly] for i in range(Lx))
|
||
|
|
|
||
|
|
def extract_key(k: bytes) -> tuple[bytes, int] | None:
|
||
|
|
Lk = len(k)
|
||
|
|
substr = b''
|
||
|
|
length = 0
|
||
|
|
for i in range(Lk):
|
||
|
|
substr += k[i:i+1]
|
||
|
|
length += 1
|
||
|
|
if k == substr*(Lk//length) + substr[:Lk%length]:
|
||
|
|
return substr, length
|
||
|
|
return None
|
||
|
|
|
||
|
|
|
||
|
|
def main() -> None:
|
||
|
|
plaintext = PLAINTEXT.encode()
|
||
|
|
cookie = b64.b64decode(COOKIE)
|
||
|
|
decoded = xorbytes(cookie, plaintext)
|
||
|
|
print('Modulated Key:', ''.join(chr(x) for x in decoded))
|
||
|
|
key, key_size = extract_key(decoded)
|
||
|
|
|
||
|
|
forged_cookie = b64.b64encode(xorbytes(FORGED_PLAINTEXT.encode(), key))
|
||
|
|
print('Forged:', forged_cookie)
|
||
|
|
|
||
|
|
|
||
|
|
if __name__ == '__main__':
|
||
|
|
try:
|
||
|
|
main()
|
||
|
|
except (KeyboardInterrupt, EOFError):
|
||
|
|
print('\n[!] Interrupt')
|