One-Time Pad Cipher
XOR text against a key to hex, and back again.
XOR encryption, explained
The one-time pad combines each byte of a message with a byte of a key using XOR. With a truly random key as long as the message and used only once, it is mathematically unbreakable.
This tool XORs your text against the key and outputs hex; decrypting with the same key returns the message. If the key is shorter it repeats, which is convenient but weakens the guarantee to that of a repeating-key cipher.
Educational and private
The XOR runs entirely in your browser, so your text and key are never uploaded.
Frequently Asked Questions
How does it work?
It XORs each byte of your message with a byte of the key, cycling the key if it is shorter, and shows the result as hex.
When is it truly unbreakable?
Only when the key is truly random, at least as long as the message, and never reused — the strict one-time pad conditions.
How do I decrypt?
Paste the hex and the same key in decrypt mode to recover the original text.
Browse the full set of free, private, in-browser tools.