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  <refentry id="function.openssl-seal">
   <refnamediv>
    <refname>openssl_seal</refname>
    <refpurpose>Seal (encrypt) data</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <methodsynopsis>
      <type>int</type><methodname>openssl_seal</methodname>
      <methodparam><type>string</type><parameter>data</parameter></methodparam>
      <methodparam><type>string</type><parameter role="reference">sealed_data</parameter></methodparam>
      <methodparam><type>array</type><parameter role="reference">env_keys</parameter></methodparam>
      <methodparam><type>array</type><parameter>pub_key_ids</parameter></methodparam>
     </methodsynopsis>
    <para>
     Returns the length of the sealed data on success, or &false; on error.
     If successful the sealed data is returned in
     <parameter>sealed_data</parameter>, and the envelope keys in
     <parameter>env_keys</parameter>.

    </para>
    <para>
     <function>openssl_seal</function> seals (encrypts)
     <parameter>data</parameter> by using RC4 with a randomly generated
     secret key. The key is encrypted with each of the public keys
     associated with the identifiers in <parameter>pub_key_ids</parameter>
     and each encrypted key is returned
     in <parameter>env_keys</parameter>. 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.
    </para>
    <para>
     <example>
      <title><function>openssl_seal</function> example</title>
      <programlisting role="php">
<![CDATA[
<?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);
?>
]]>
      </programlisting>
     </example>
    </para>
    <simpara>
     See also <function>openssl_open</function>.
    </simpara>
   </refsect1>
  </refentry>

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