(PHP 7 >= 7.2.0, PHP 8)
sodium_crypto_box — Authenticated public-key encryption
$message, string $nonce, string $key_pair): stringEncrypt a message using asymmetric (public key) cryptography.
The algorithm used by functions prefixed with sodium_crypto_box() are Elliptic Curve Diffie-Hellman over the Montgomery curve, Curve25519; usually abbreviated as X25519.
messageThe message to be encrypted.
nonceA 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_pairSee sodium_crypto_box_keypair_from_secretkey_and_publickey(). This should include the sender's X25519 secret key and the recipient's X25519 public key.
Returns the encrypted message (ciphertext plus authentication tag). The ciphertext will be 16 bytes longer than the plaintext, and a raw binary string. See sodium_bin2base64() for safe encoding for storage.