~/tools $ ./xor --brute
Cipher Workbench
Brute-force Caesar and single-byte XOR with English scoring, and run repeating-key XOR and Vigenère.
Runs entirely in your browser. Nothing you paste is sent anywhere.
Candidates (best guess highlighted)
Why these ciphers still matter
None of these are secure, which is the point. They show up constantly in CTFs, in malware that obfuscates strings with a one-byte XOR key, and in homegrown "encryption" during real assessments. Recognizing them quickly saves hours.
How the ranking works
Each candidate is scored by how closely its characters match English letter frequencies, with heavy penalties for unprintable bytes. It is the same technique used to break these ciphers by hand, automated. Short inputs give less reliable rankings. For the theory, see Cryptography.