Rating:
# XOR
```python
import os
FLAG = b'OFPPT-CTF{...REDACTED...}'
class HoneyComb:
def __init__(self, key):
self.vals = [i for i in key]
def turn(self):
self.vals = [self.vals[-1]] + self.vals[:-1]
def encrypt(self, msg):
keystream = []
while len(keystream) < len(msg):
keystream += self.vals
self.turn()
return bytes([msg[i] ^ keystream[i] for i in range(len(msg))]).hex()
hc = HoneyComb(os.urandom(6))
print(hc.encrypt(FLAG))
```
first it creates a key of length 6 bytes then if lenght of key < lenght message it adds the of the key to another variable then it shifts the key
becuase the key is too small we know that the flag begin with OFPPT- we can xor first six bytes of ciphertext with first six bytes and we get the key then we can xor it with the ciphertext and every 6 bytes we can shift the key
```python
from pwn import xor
plaintext =b'OFPPT-'
ciphertext = bytes.fromhex('48ac3fe745bed053ac14ef2163cc70db58dfe862fe33860330dc22ea589c9f03d922e13365db038626eaee')
key = xor(plaintext, ciphertext[:6])
keyst =[]
for i in key :
keyst.append(i)
keystream = []
while len(keystream) < len(ciphertext):
keystream += keyst
keyst =[keyst[-1]] + keyst[:-1]
print(xor(keystream , ciphertext))
```
flag is : OFPPT-CTF{X0r_w17h_sm4ll_k3y_vuln3r4b1l17y}
