(Visual FoxPro) Verify HMAC XML Digital Signature

Demonstrates how to validate an XML digital signature signed with an HMAC key.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lcUrl
LOCAL loHttp
LOCAL loSbXml
LOCAL lnSuccess
LOCAL loVerifier
LOCAL lnBVerified

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

* The XML containing the Signature to be verified contains the following:

* <?xml version="1.0" encoding="UTF-8" standalone="no"?>
* <collection Id="root">
* 	<album>
* 		<title>Questions, unanswered</title>
* 		<artist>Steve and the flubberblubs</artist>
* 		<year>1989</year>
* 		<t:tracks xmlns:t="http://test.xades4j/tracks">
* 			<t:song length="4:05" tracknumber="1">
* 				<t:title>What do you know?</t:title>
* 				<t:artist>Steve and the flubberblubs</t:artist>
* 				<t:lastplayed>2006-10-17-08:31</t:lastplayed>
* 			</t:song>
* 			<t:song length="3:45" tracknumber="2">
* 				<t:title>Who do you know?</t:title>
* 				<t:artist>Steve and the flubberblubs</t:artist>
* 				<t:lastplayed>2006-10-17-08:35</t:lastplayed>
* 			</t:song>
* 			<t:song length="5:14" tracknumber="3">
* 				<t:title>When do you know?</t:title>
* 				<t:artist>Steve and the flubberblubs</t:artist>
* 				<t:lastplayed>2006-10-17-08:39</t:lastplayed>
* 			</t:song>
* 			<t:song length="4:19" tracknumber="4">
* 				<t:title>Do you know?</t:title>
* 				<t:artist>Steve and the flubberblubs</t:artist>
* 				<t:lastplayed>2006-10-17-08:44</t:lastplayed>
* 			</t:song>
* 		</t:tracks>
* 	</album>
* <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#hmac-sha256"/><ds:Reference URI="#root"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>rD/g8soqKz8EiPUBhEWfcQacS0ta4ULHX3dKMEH6ZoQ=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>R8dXP95VRYJBfL6d0Peogybdk27+R+JIfX8jnVu0NOI=</ds:SignatureValue></ds:Signature></collection>

* The above XML is available at https://www.chilkatsoft.com/exampleData/hmacSigned.xml
* First fetch the XML..

lcUrl = "https://www.chilkatsoft.com/exampleData/hmacSigned.xml"
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbXml = CreateObject('Chilkat.StringBuilder')
lnSuccess = loHttp.QuickGetSb(lcUrl,loSbXml)
IF (lnSuccess <> 1) THEN
    ? loHttp.LastErrorText
    RELEASE loHttp
    RELEASE loSbXml
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.XmlDSig')
loVerifier = CreateObject('Chilkat.XmlDSig')

* Load the XML containing the signature to be verified.
lnSuccess = loVerifier.LoadSignatureSb(loSbXml)
IF (lnSuccess <> 1) THEN
    ? loVerifier.LastErrorText
    RELEASE loHttp
    RELEASE loSbXml
    RELEASE loVerifier
    CANCEL
ENDIF

* Provide the HMAC key
* The HMAC key for this signature is the us-ascii bytes of the string "secret",
* It can be set in any of the following ways (and also more ways not shown here..)
loVerifier.SetHmacKey("secret","ascii")
* or
loVerifier.SetHmacKey("c2VjcmV0","base64")
* or
loVerifier.SetHmacKey("736563726574","hex")

* Verify the signature
lnBVerified = loVerifier.VerifySignature(1)
? "Signature verified = " + STR(lnBVerified)

RELEASE loHttp
RELEASE loSbXml
RELEASE loVerifier