(PHP Extension) Verify an XML Signature with Multiple References

Demonstrates how to verify an XML digital signature that contains multiple references.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// An example of an enveloping XML signature with mulitple references is available at
// https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml

// This example will show how to verify the signature and all references, and also how
// to verify each reference individually.  This is useful to distinguish which part
// of the XML signature validation failed.  It could be that one or more of the references
// failed because of a hash computation mismatch.  Or it could be that the signature over
// the SignedInfo failed.  

// First, let's grab the sample XML signature.
$http = new CkHttp();
$sbXml = new CkStringBuilder();
$success = $http->QuickGetSb('https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml',$sbXml);
if ($success != true) {
    print $http->lastErrorText() . "\n";
    exit;
}

// Load the XML containing the signature to be verified.
$verifier = new CkXmlDSig();
$success = $verifier->LoadSignatureSb($sbXml);
if ($success != true) {
    print $verifier->lastErrorText() . "\n";
    exit;
}

$verifyReferenceDigests = true;

// The quick way to validate all references and the signature over the SignedInfo
// is to call VerifySignature with verifyReferenceDigests equal to true.
$verified = $verifier->VerifySignature($verifyReferenceDigests);
print 'Signature and all reference digests verified = ' . $verified . "\n";

// Let's pretend the call to VerifySignature returned false.  Something did not validate.
// Was it one or more of the References that did not hash to the correct value?
// Or was it the signature over the SignedInfo that failed?
// We can check just the signature over the SignedInfo by passing false to VerifySignature.
// This allows us to skip the hashing and checking each Reference.  
$verifyReferenceDigests = false;
$signedInfoVerified = $verifier->VerifySignature($verifyReferenceDigests);
print 'Neglecting the reference hashes, the SignedInfo validation result = ' . $signedInfoVerified . "\n";

// We can also verify each reference digest separately
$numRefs = $verifier->get_NumReferences();
$i = 0;
while ($i < $numRefs) {
    $refDigestVerified = $verifier->VerifyReferenceDigest($i);
    print 'Reference ' . $i . ' digest verified = ' . $refDigestVerified . "\n";
    $i = $i + 1;
}

// For this sample XML signature with 3 References, we get the following output:

// Signature and all reference digests verified = True
// Neglecting the reference hashes, the SignedInfo validation result = True
// Reference 0 digest verified = True
// Reference 1 digest verified = True
// Reference 2 digest verified = Tru

?>