Exclusive Cipher
Category: Crypto
40 points
Clam decided to return to classic cryptography and revisit the XOR cipher! Here’s some hex encoded ciphertext:
ae27eb3a148c3cf031079921ea3315cd27eb7d02882bf724169921eb3a469920e07d0b883bf63c018869a5090e8868e331078a68ec2e468c2bf13b1d9a20ea0208882de12e398c2df60211852deb021f823dda35079b2dda25099f35ab7d218227e17d0a982bee7d098368f13503cd27f135039f68e62f1f9d3cea7c The key is 5 bytes long and the flag is somewhere in the message.
Author: aplet123
Solution
from pwn import xor
encrypted = bytes.fromhex('ae27eb3a148c3cf031079921ea3315cd27eb7d02882bf724169921eb3a469920e07d0b883bf63c018869a5'
'090e8868e331078a68ec2e468c2bf13b1d9a20ea0208882de12e398c2df60211852deb021f823dda35079b'
'2dda25099f35ab7d218227e17d0a982bee7d098368f13503cd27f135039f68e62f1f9d3cea7c')
for i in range(len(encrypted)):
key = xor(encrypted[i:i+5], b'actf{')
print(xor(encrypted, key))Somewhere in the output…
b'Congratulations on decrypting the message! The flag is actf{who_needs_aes_when_you_have_xor}. Good luck on the other crypto!'Flag
actf{who_needs_aes_when_you_have_xor}