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openssl_seal

(PHP 4 >= 4.0.4)

openssl_seal -- Seal (encrypt) data

Description

int openssl_seal (string data, string sealed_data, array env_keys, array pub_key_ids)

Warning

This function is EXPERIMENTAL. That means, that the behaviour of this function, this function name, in concreto ANYTHING documented here can change in a future release of PHP WITHOUT NOTICE. Be warned, and use this function at your own risk.

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 env_keys.

openssl_seal() seals (encrypts) data by using RC4 with a randomly generated secret key. The key is encrypted with each of the public keys associated with the identifiers in pub_key_ids and each encrypted key is returned in env_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.

Example 1. openssl_seal() example


// $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);

See also openssl_open().

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