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Tool Factory

Cryptography & Ciphers

XTEA Decryption

Decrypt XTEA ciphertext with a 16-byte key. Match mode, IV, padding, and the round count, which defaults to 32.

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Input

Paste ciphertext as Hex, Base64, or Raw bytes. Match Input format. Use Load example to check the settings.

Options

Use exactly 16 bytes (128 bits). Hex requires 32 digits. UTF8 uses encoded bytes, not character counts.

Use exactly 8 bytes, or leave blank for eight zero bytes. ECB ignores the IV.

Match the sender. CFB uses 64-bit feedback. CTR increments the complete 8-byte counter in big-endian order.

Choose the ciphertext encoding. File reads binary bytes, not a file containing Hex or Base64 text.

Raw requires valid UTF-8 text. Choose Hex for binary plaintext or uncertain settings.

CBC and ECB use this setting. PKCS5 matches PKCS7 for 8-byte blocks. NO, ZERO, and RANDOM retain padding bytes.

32 cycles perform 64 half-rounds. Some libraries call this 64 rounds. Match cycles, not the label alone.

Ready for a result

Decrypt XTEA ciphertext with a 16-byte key. Match mode, IV, padding, and the round count, which defaults to 32.

This tool runs open-source code from CyberChef by GCHQ (Apache License 2.0). See open-source credits.

XTEA reads key and data as big-endian words. Rounds counts complete cycles, not individual half-rounds.

The result contains plaintext in the selected output representation.

  • Decrypt a configuration blob or string table during malware analysis when the key is known.

Sources: Go XTEA block implementation and round convention; Go XTEA implementation and published test vectors; Bouncy Castle XTEA test vectors

Match key words, cycles, and mode

  1. Choose ciphertext Input format and enter the key with its format.
  2. Match Mode, IV, Padding, and Rounds to the sender.
  3. Use File only for binary ciphertext, not a file containing encoded text.

Decrypt one XTEA block

Input: 497df3d072612cb5

Settings: Key format Hex, Key 000102030405060708090a0b0c0d0e0f, IV empty, Mode ECB, Input Hex, Output Hex, Padding NO, and Rounds 32.

Result: 4142434445464748

XTEA Decryption returns the bytes of ABCDEFGH; Output Raw shows that text. Padding must be NO, because this single block carries no padding. With PKCS5 the tool reports “Invalid PKCS#5 padding.”

Byte order and unauthenticated output

  • CFB uses 64-bit feedback. CTR increments the complete counter in big-endian order.
  • A blank IV selects zero bytes. Use it only when the sender did the same.
  • Remove headers and salt prefixes before decoding. TEA and XXTEA require different tools.
  • XTEA provides no authentication and serves legacy compatibility.