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SALLY Challenge #2 - Reign

This challenge can be found when Eli listens for vulns in the airlock's smart lock code.

The Setup

Help us decrypt this message! We suspect it's using some kind of exclusive bitwise cipher?

We can use the key from around the lock dial, but we're not sure where the key starts.

We are given a hexadecimal message to decrypt.

The Key

In the comic, we can see a hexadecimal key around the lock. This must be the same key the message above references.

The "exclusive" bitwise cipher is probably the XOR cipher, as XOR is the "exclusive disjunction" (exclusive or).

Using CyberChef with the "From Hex" and "XOR" operations, we can try decrypting the message. The long encrypted message goes in the "Input" and the key from the comic goes into the "XOR" operation's "Key" field.

This gives us gibberish, but the setup mentions that "we're not sure where the key starts". The key has 8 bytes (8 2-character hexadecimal units), so we can try the 8 possibilities (12345678 then 23456781 then 34567812 etc).

One of them gives us the authorization code, which is our flag!