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A MetroRide dispatcher found a USB stick in the lost-and-found. It holds one file: a short message, scrambled with a single-byte XOR key.
XOR with one byte is a classic beginner cipher. The same key byte is XORed with every byte of the message, and XORing twice with the same key gives you the original back.
What you are given: the scrambled message as hex bytes, below.
What to find: the flag. You know every flag on this platform starts with the letters MXC plus an opening curly brace, and ends with a closing brace. That is your way in: XOR the first bytes of the ciphertext with the characters M, X, C and an opening brace, and the key byte falls out.
How to work: pen and paper works, but a tiny script is faster. There are only 256 possible keys, so you can also try them all and keep the one that gives readable text.
Scrambled message (hex):
37223901021508250d130e12251b250913141d161f2518030e1f251b174e0007
Submit the flag when you have it.
This challenge only. All names, addresses and data are fictional. Do not test any real system.
Stuck? Open hints in order: a nudge, then the next step, then an explicit pointer. Costs are taken from this solve's points.
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