sodium_crypto_secretbox_open
Authenticated shared-key decryption
Description
stringfalse sodium_crypto_secretbox_open(string $ciphertext, string $nonce, #[\SensitiveParameter]string $key)
Decrypt an encrypted message with a symmetric (shared) key.
Parameters
-
ciphertext
-
Must be in the format provided by sodium_crypto_secretbox
(ciphertext and tag, concatenated).
-
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
The decrypted string on success or false on failure.
Examples
Example #1 sodium_crypto_secretbox_open example
<?php
// The $key must be kept confidential
$key = random_bytes(SODIUM_CRYPTO_SECRETBOX_KEYBYTES);
// Do not reuse $nonce with the same key
$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
$ciphertext = sodium_crypto_secretbox('message to be encrypted', $nonce, $key);
// The same nonce and key are required to decrypt the $ciphertext
$plaintext = sodium_crypto_secretbox_open($ciphertext, $nonce, $key);
if ($plaintext !== false) {
echo $plaintext . PHP_EOL;
}
?>
The above example will output:
See Also
- sodium_crypto_secretbox
- sodium_crypto_secretbox_keygen
- random_bytes