PHP

Verify an XML Signature with Multiple References

See more XML Digital Signatures Examples

Demonstrates how to verify an XML digital signature that contains multiple references. Chilkat2 PHP

<?php

use Chilkat2\Http;
use Chilkat2\StringBuilder;
use Chilkat2\XmlDSig;

// 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 Http();
$sbXml = new StringBuilder();
try {
    $http->QuickGetSb('https://www.chilkatsoft.com/exampleData/envelopedMultipleRefs.xml', $sbXml);

    // Load the XML containing the signature to be verified.
    $verifier = new XmlDSig();
    $verifier->LoadSignatureSb($sbXml);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\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.
try {
    $verifier->VerifySignature($verifyReferenceDigests);
    $verified = true;
} catch (\Chilkat2\Exception $e) {
    $verified = false;
}
echo 'Signature and all reference digests verified = ', ($verified ? 'true' : 'false'), "\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;
try {
    $verifier->VerifySignature($verifyReferenceDigests);
    $signedInfoVerified = true;
} catch (\Chilkat2\Exception $e) {
    $signedInfoVerified = false;
}
echo 'Neglecting the reference hashes, the SignedInfo validation result = ', ($signedInfoVerified ? 'true' : 'false'), "\n";

// We can also verify each reference digest separately
$numRefs = $verifier->NumReferences;
$i = 0;
while ($i < $numRefs) {
    $refDigestVerified = $verifier->VerifyReferenceDigest($i);
    echo 'Reference ', $i, ' digest verified = ', ($refDigestVerified ? 'true' : 'false'), "\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 = True