Text XOR with Hex Key
Enter text and an even-length hexadecimal key. The key repeats across UTF-8 bytes; the output is decoded as UTF-8 when valid.
A QUICK WALKTHROUGH
How to use this tool
- Enter up to 100,000 characters of text.
- Enter 1–64 hexadecimal key bytes using pairs such as 0f4a.
- Run the reversible byte-wise XOR and review the UTF-8 output.
Explicit byte contract
Text is encoded as UTF-8 bytes. The key must contain 1–64 complete byte pairs (even-length hexadecimal, with optional spaces between pairs). The key repeats cyclically, and the same operation reverses the result when the output is valid UTF-8.
Bounded local processing
At most 100,000 characters and 64 key bytes are accepted. Validation and transformation run in this browser; no text or key is uploaded or stored.
Not secure encryption
Repeating-key XOR is a reversible transform, not modern encryption. Do not use it to protect secrets or infer cryptographic security from the output.
GOOD TO KNOW
Common questions
Does this encrypt text securely?
No. Repeating-key XOR is educational and reversible, but it does not provide modern confidentiality.
Why must the key have an even number of hex digits?
Each pair represents one byte from 00 through ff; incomplete nibbles are rejected.
Can I process emoji or non-Latin text?
Yes. Input is transformed as UTF-8 bytes, so Unicode text is handled consistently.