OpenSSL Functions
PHP Manual

openssl_seal

Seal (encrypt) data

Description

intfalse openssl_seal(
    #[\SensitiveParameter]string $data,
    string &$sealed_data,
    array &$encrypted_keys,
    array $public_key,
    string $cipher_algo,
    string &$iv = null
)

openssl_seal seals (encrypts) data using the specified cipher_algo with a randomly generated secret key. The key is then encrypted with each of the public keys in public_key array, and each encrypted envelope key is returned in encrypted_keys. This allows sealed data to be sent to multiple recipients (provided their public keys are available). Each recipient must receive both the sealed data and the envelope key that was encrypted with the recipient's public key. The IV (Initialization Vector) is generated, and its value is returned in iv.

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 for PHP versions prior to 8.0 is ('RC4') which is considered insecure. It is strongly recommended to explicitly specify a secure cipher method.

iv

The initialization vector for decryption of data. It is required if the cipher method requires IV. This can be found out by calling openssl_cipher_iv_length with cipher_algo.

Caution

The IV cannot be set explicitly. Any value set in it is overwritten by randomly generated value.

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
$data = "test";

// fetch public keys
$pk1 = openssl_get_publickey("file://cert1.pem");
$pk2 = openssl_get_publickey("file://cert2.pem");

// seal message, only owners of $pk1 and $pk2 can decrypt $sealed with keys
// $ekeys[0] and $ekeys[1] respectively.
if (openssl_seal($data, $sealed, $ekeys, array($pk1, $pk2), 'AES256', $iv) > 0) {
    // possibly store the $sealed and $iv values and use later in openssl_open
    echo "success\n";
}
?>

See Also

  • openssl_open