ChaCha20-Poly1305 Decryption

Decrypt and verify ChaCha20-Poly1305 or XChaCha20-Poly1305 text or files online using a 256-bit key, nonce, AAD, tag, and PBKDF2, EvpKDF, or HKDF key derivation. Read more

ChaCha20-Poly1305 decryption online

Decrypt and verify ChaCha20-Poly1305 or XChaCha20-Poly1305 ciphertext. Keep Append Tag enabled when the final bytes of the input contain the authentication tag. Disable it when the tag is stored separately, then enter the detached Authentication Tag.

How to decrypt

  1. Paste ciphertext or upload a file and select the input encoding.
  2. Choose ChaCha20-Poly1305 or XChaCha20-Poly1305.
  3. Enter the key and nonce, optional AAD, and matching KDF settings if used.
  4. Choose Append Tag or enter a detached 16-byte Authentication Tag.
  5. Decrypt; authentication failures surface as a decrypt error.

Matching parameters

ChaCha20-Poly1305 uses a 96-bit nonce; XChaCha20-Poly1305 uses a 192-bit nonce. Wrong key, nonce, AAD, or tag fails verification. Tag length is fixed at 16 bytes.

Frequently asked questions

Why do I get a bad decrypt error?

Confirm algorithm, key or KDF settings, nonce, AAD, and whether the tag is appended or detached. Any mismatch fails authentication.

Input
Output
Share Link
Settings
Decrypt
Nonce
AAD