XML : How to get attribute value from xml / MPD file?

Im trying to get to values from attributes on a MPD file, which is an XML file, in other to pass it to another function. No luck until now. I'll appreciate any help.

Thanks.

Values im looking on : default_KID

XML File:

  <ContentProtection schemeIdUri="urn:uuid:5E629AF5-38DA-4063-8977-97FFBD9902D4" value="Marlin">              <cenc:pssh>AAAAKHBzc2gAAAAAXmKa9TjaQGOJd5f/vZkC1AAAAAgAAAAIbWFybA==</cenc:pssh>              <mas:MarlinContentIds>    <mas:MarlinContentId>urn:marlin:kid:42eb30ca4481312db87a91119d6f0b28</mas:MarlinContentId></mas:MarlinContentIds>          </ContentProtection>