Encrypt text with authenticated encryption

Protect bytes with the RFC 8439 ChaCha20-Poly1305 construction.

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ToolChaCha20-Poly1305 Encrypt
Input
Output
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Preview

How it works

ChaCha20 generates a keystream from a 256-bit key and nonce, plaintext is XORed with it, and Poly1305 authenticates ciphertext plus additional data; the tag is appended. Verification requires the original nonce and key.

  • The IETF construction uses a 96-bit nonce and 128-bit tag.
  • Nonce uniqueness is required per key.

Worked example

Encrypt with ChaCha20
Encrypt a message using ChaCha20-Poly1305 authenticated encryption
Input
											Input: Top secret data
Key: MySecretKey123!
Output
												yDvmSBPD2nfyrFVN3jHjGLr8ZsL8WuUD8qOvqj6WRrUSJH+EPWiH8sP01m3sSmDZ1WFabxGWtT5kDYg=

When to use this

Mobile protocols, token storage, and AEAD test vectors use this construction.

Edge cases

  • Nonce reuse breaks confidentiality guarantees.
  • Changing additional data causes tag failure.
  • A modified tag must reject the message.

References