>Returns:</th><td class="field-body"><p class="first">A pseudo-random key or FALSE on failure</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>Derives a key from another, presumably weaker key.</p>
<p>This method is used internally to derive an encryption and HMAC key
from your configured <em>encryption_key</em>.</p>
<p>It is publicly available due to its otherwise general purpose. It 