Repeating-key XOR | Hunt the Flag

Labs need a computer

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Files

crypto-xor.zip
Size: 1.2 KB
SHA-256
c03078bc46325326aecaa0d81d2222f6d29213f5e81196e26f0b8860592b9c61
Download

After downloading, compare the file SHA-256 with the value shown here to make sure it arrived intact.

Tools you may need

CyberChef
A browser tool for XOR operations and analysis.

Scenario

The falcon intercepted a Ravens note hidden with a repeating-key XOR using a short word. The text is English, begins with a predictable phrase, and the secret code sits in the middle.

What you are looking at

You download crypto-xor.zip with note.enc and cipher.hex: the text XOR-encrypted with a repeating six-letter key, and the text is known to start with a fixed phrase.

Goal

Recover the key from the known phrase, then decrypt the whole note and extract the flag.

What counts as solved

You enter the correct flag.

Method checklist

Tick each step as you work through it. The steps are the method, not the answer.

Unzip and view the bytes in hex.
XOR the start with the known phrase to extract the key.
Repeat the key over the whole text.
Read the text and extract the flag.

Hints

You have not revealed a hint yet. Ask the falcon when you need one.