sodium_crypto_aead_xchacha20poly1305_ietf_encrypt

(PHP 7 >= 7.2.0, PHP 8)

sodium_crypto_aead_xchacha20poly1305_ietf_encrypt — (Preferred) Encrypt then authenticate with XChaCha20-Poly1305

function sodium_crypto_aead_xchacha20poly1305_ietf_encrypt(
    #[\SensitiveParameter] string $message,
    string $additional_data,
    string $nonce,
    #[\SensitiveParameter] string $key
): string

Encrypt then authenticate with XChaCha20-Poly1305 (eXtended-nonce variant).

Generally, XChaCha20-Poly1305 is the best of the provided AEAD modes to use.

message: The plaintext message to encrypt.
additional_data: Additional, authenticated data. This is used in the verification of the authentication tag appended to the ciphertext, but it is not encrypted or stored in the ciphertext.
nonce: A number that must be only used once, per message. 24 bytes long. This is a large enough bound to generate randomly (i.e. random_bytes()).
key: Encryption key (256-bit).

Returns the ciphertext and authentication tag as a string of raw binary bytes.