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A message was XOR-encrypted with a single unknown byte and hex-encoded. Recover the flag. Hint: there are only 256 possible keys — brute-force them and look for the one that produces readable text starting with CLV{.
#crypto#xor#brute-force#beginner
DifficultyEasy
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Hints
Unlocking any hint — including free ones — forfeits the +25% no-hint solve bonus.
Every byte of the plaintext is XORed with the same one-byte key. Applying the same key again restores the original, so the cipher is symmetric but offers very little security.
Why is single-byte XOR easy to break?
There are only 256 possible keys. You can try them all and pick the output that looks like readable text, often using simple scoring such as English letter frequency.
Can I solve this challenge with Python?
Yes. A short loop over every key from 0 to 255 is enough, and the challenge is free on Codelivly, so it is a good first scripting exercise in cryptography.