xorxorxor

EASY , Crypto

DESCRIPTION: Who needs AES when you have XOR?

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By looking at python code for encryption we know that length of key is 4 and

flag xor key = encrypted text so, if we do xor of cipher text and first 4 character of flag that we know is "HTB{" we get the key.

(encrypted text) xor 'HTB{' = key

now we have the key to decrypt the flag:

cipher xor key = flag

python code:

from pwnlib.util.fiddling import unhex, xor
eb = bytes.fromhex('134af6e1297bc4a96f6a87fe046684e8047084ee046d84c5282dd7ef292dc9')
key = xor(eb, b'HTB{')[:4]
print(xor(eb, key).decode())

flag: HTB{rep34t3d_x0r_n0t_s0_s3cur3}