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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. The behaviour of this function, the name of this function, and anything else documented about this function may 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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