XML Signature DigestValue is invalid

Question

I am trying to sign XML file with PHP and xmlseclibs. However all validation tools say that my signature is invalid. XMLSpy says: "The calculated digest value doesn't match the digest of reference"

This is my XML:

<root><value>x</value></root>

This is the digest I get:

KaMTM32K5rXl9U6MgG2BXuzNxoQ=

Methods I used to get it:

1.) PHP:

$doc = new DOMDocument();
$doc->loadXML('<root><value>x</value></root>');
echo base64_encode(sha1($doc->documentElement->C14N(), true));

2.) OpenSSL:

openssl dgst -binary -sha1 test.xml | openssl enc -base64

3.) This website: http://hash.online-convert.com/sha1-generator

This is the digest that XMLSpy somehow gets and that works:

HedaN7TMgHgq2bRypzavMuFLoCg=

How do I get this digest?

Answer 1

XMLSpy formats XML before it signs it. It adds line feeds and tabs and C14N does not remove these. When you remove <Signature> you are left with this XML which is used to calculate digest:

<root>
    <value>x</value>

</root>

Another thing XMLSpy does is that it adds attribute URI="" to <Reference>. PHP library xmlseclibs doesn't do that by default. So I changed my code to this:

$objDSig->addReference($doc, XMLSecurityDSig::SHA1, array('http://www.w3.org/2000/09/xmldsig#enveloped-signature'), array('force_uri' => TRUE));