(PHP 7 >= 7.2.0, PHP 8)
sodium_crypto_secretbox — Authenticated shared-key encryption
$message, string $nonce, #[\SensitiveParameter] string $key): stringEncrypt a message with a symmetric (shared) key.
messageThe plaintext message to encrypt.
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()).
keyEncryption key (256-bit).
Returns the encrypted string.
nonce has a length of bytes different than
SODIUM_CRYPTO_SECRETBOX_NONCEBYTES
(24 bytes), a SodiumException will be thrown.
key has a length of bytes different than
SODIUM_CRYPTO_SECRETBOX_KEYBYTES
(32 bytes), a SodiumException will be thrown.
Example #1 sodium_crypto_secretbox() example
<?php
// The $key must be kept confidential
$key = sodium_crypto_secretbox_keygen();
// Do not reuse $nonce with the same key
$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
$plaintext = "message to be encrypted";
$ciphertext = sodium_crypto_secretbox($plaintext, $nonce, $key);
var_dump(bin2hex($ciphertext));
// The same nonce and key are required to decrypt the $ciphertext
var_dump(sodium_crypto_secretbox_open($ciphertext, $nonce, $key));
?>The above example will output something similar to:
string(78) "3a1fa3e9f7b72ef8be51d40abf8e296c6899c185d07b18b4c93e7f26aa776d24c50852cd6b1076" string(23) "message to be encrypted"
An example to how encrypt or decrypt using sodium:
<?php
$key = random_bytes(SODIUM_CRYPTO_SECRETBOX_KEYBYTES);
$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
$ciphertext = sodium_crypto_secretbox("Hello World !", $nonce, $key);
$plaintext = sodium_crypto_secretbox_open($ciphertext, $nonce, $key);
if ($plaintext === false) {
throw new Exception("Bad ciphertext");
}
echo $plaintext;