<xenc:DataReference xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" URI="#Encrypted_DATA_ID">
  <ds:Transforms xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
    <ds:Transform Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
      <ds:XPath>self::xenc:EncryptedData[@Id="example1"]</ds:XPath>
    </ds:Transform>
  </ds:Transforms>
</xenc:DataReference>