sodium_crypto_secretbox
(PHP 7 >= 7.2.0, PHP 8)
sodium_crypto_secretbox — Authenticated shared-key encryption
Description
sodium_crypto_secretbox(string
$message, string $nonce, string $key): stringEncrypt a message with a symmetric (shared) key.
Parameters
-
message -
The plaintext message to encrypt.
-
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).
Return Values
Returns the encrypted string.
Errors/Exceptions
-
If
noncehas a length of bytes different thanSODIUM_CRYPTO_SECRETBOX_NONCEBYTES(24 bytes), a SodiumException will be thrown. -
If
keyhas a length of bytes different thanSODIUM_CRYPTO_SECRETBOX_KEYBYTES(32 bytes), a SodiumException will be thrown. - Throws a SodiumException on failure.
Examples
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 nouce 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"
See Also
- sodium_crypto_secretbox_open() - Authenticated shared-key decryption
- sodium_crypto_secretbox_keygen() - Generate random key for sodium_crypto_secretbox
- random_bytes() - Generates cryptographically secure pseudo-random bytes
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