XOR Cipher

Encrypt with a XOR cipher

The XOR cipher encrypts data by combining each byte of the message with a byte of a repeating key using the exclusive-or operation. It is a fundamental building block in cryptography because XOR is reversible: applying the same key again decrypts the data. This tool encodes text to a hexadecimal string using your key, and decodes a hex string back to text with the same key, since encryption and decryption are the identical operation.

The text is encoded as UTF-8 bytes first, so it handles any characters, and the output is shown in hex because XOR produces non-printable bytes.

Strengths and weaknesses

XOR is at the heart of serious cryptography, including the one-time pad, which is provably secure when the key is truly random and as long as the message and never reused. However, the simple repeating-key XOR shown here is weak: a short, reused key can be recovered through frequency analysis, so it must not be used to protect real secrets. It is excellent for learning how symmetric encryption works and for lightweight obfuscation.

For genuine security, use a modern cipher like AES with a proper key. This tool is for education and experimentation. All processing happens locally in your browser.

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