openssl_seal

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

openssl_seal — Seal (encrypt) data

Description

openssl_seal(
    string$data,
    string&$sealed_data,
    array&$encrypted_keys,
    array$public_key,
    string$cipher_algo,
    string&$iv = null
): int|false

openssl_seal() seals (encrypts) data by using the given cipher_algo with a randomly generated secret key. The key is encrypted with each of the public keys associated with the identifiers in public_key and each encrypted key is returned in encrypted_keys. This means that one can send sealed data to multiple recipients (provided one has obtained their public keys). Each recipient must receive both the sealed data and the envelope key that was encrypted with the recipient's public key.

Parameters

data: The data to seal.
sealed_data: The sealed data.
encrypted_keys: Array of encrypted keys.
public_key: Array of OpenSSLAsymmetricKey instances containing public keys.
cipher_algo: The cipher method.
Caution
The default value ('RC4') is considered insecure. It is strongly recommended to explicitly specify a secure cipher method.
iv: The initialization vector.

Return Values

Returns the length of the sealed data on success, or false on error. If successful the sealed data is returned in sealed_data, and the envelope keys in encrypted_keys.

Changelog

Version	Description
8.0.0	`public_key` accepts an array of OpenSSLAsymmetricKey instances now; previously, an array of resources of type `OpenSSL key` was accepted.
8.0.0	`cipher_algo` is no longer an optional parameter.
8.0.0	`iv` is nullable now.

Examples

Example #1 openssl_seal() example

<?php
// $data is assumed to contain the data to be sealed

// fetch public keys for our recipients, and ready them
$fp = fopen("/src/openssl-0.9.6/demos/maurice/cert.pem", "r");
$cert = fread($fp, 8192);
fclose($fp);
$pk1 = openssl_get_publickey($cert);
// Repeat for second recipient
$fp = fopen("/src/openssl-0.9.6/demos/sign/cert.pem", "r");
$cert = fread($fp, 8192);
fclose($fp);
$pk2 = openssl_get_publickey($cert);

// seal message, only owners of $pk1 and $pk2 can decrypt $sealed with keys
// $ekeys[0] and $ekeys[1] respectively.
openssl_seal($data, $sealed, $ekeys, array($pk1, $pk2));

// free the keys from memory
openssl_free_key($pk1);
openssl_free_key($pk2);
?>