XXTEA Decryption

XXTEA decryption online

XXTEA decryption reverses Corrected Block TEA over a variable-length array of 32-bit words using a 128-bit key. This tool expects ciphertext in its length-preserving wrapper format: the decrypted final word stores the original byte count and is removed from the output.

How to use this tool

Paste Hex or Base64 ciphertext, or choose a local file. Select the original key type. Text Key converts the text to UTF-8, then zero-pads or truncates it to 16 bytes; Custom Key requires exactly 16 decoded bytes. Decrypt and view or download the recovered data.

Matching cipher parameters

This page is directly compatible with XXTEA encryption: it reads little-endian 32-bit words and validates the embedded original-length field. A library that uses big-endian words, omits the length, encodes strings differently, or adds another wrapper will not interoperate without conversion.

XXTEA has no block mode, padding selector, IV, salt, or passphrase derivation on this page. The decoded ciphertext length must be divisible by four and contain enough words for the wrapped format.

Security warning

XXTEA is suitable here for legacy recovery, tests, and explicit interoperability. It has no authentication tag, and published cryptanalysis gives a chosen-plaintext attack on the full cipher. Prefer AES decryption for compatible modern authenticated formats, and avoid handling production secrets on an untrusted device or browser.

Frequently asked questions

Why can I not recover the original plaintext?

Compare the key bytes, UTF-8 conversion, byte order, embedded-length convention, and ciphertext encoding. A wrong key may fail the length check, but that check is a formatting test rather than cryptographic authentication.

Does encryption detect tampering?

No. Passing the embedded-length check or producing readable text does not prove that the ciphertext is genuine or unchanged.