(Visual FoxPro) Extract SignatureValue from Signed XML

See more XML Digital Signatures Examples

Demonstrates how to extract the signature value from signed XML.

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

LOCAL lcFilePath
LOCAL loSb
LOCAL lnSuccess
LOCAL lcBase64Sig
LOCAL loXml
LOCAL loXSigVal

* This example will work with the following signed XML, which as been reformatted for readability.

* <?xml version="1.0" encoding="utf-8"?>
* <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
*     <SOAP-ENV:Header>
*         <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1">
*             <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#">
*                         <InclusiveNamespaces xmlns="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse SOAP-ENV"/>
*                     </ds:CanonicalizationMethod>
*                     <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
*                     <ds:Reference URI="#Body">
*                         <ds:Transforms>
*                             <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
*                         </ds:Transforms>
*                         <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
*                         <ds:DigestValue>OwgHPZNfDkXnZsjpfzXqAcT3RV3HzmTsEy2bP44FJ0M=</ds:DigestValue>
*                     </ds:Reference>
*                 </ds:SignedInfo>
*                 <ds:SignatureValue>C+7FWngU....DJFBcdg==</ds:SignatureValue>
*                 <ds:KeyInfo>
*                     <ds:KeyValue>
*                         <ds:RSAKeyValue>
*                             <ds:Modulus>sXeRhM55P13.....NAcibRw==</ds:Modulus>
*                             <ds:Exponent>AQAB</ds:Exponent>
*                         </ds:RSAKeyValue>
*                     </ds:KeyValue>
*                 </ds:KeyInfo>
*             </ds:Signature>
*         </wsse:Security>
*     </SOAP-ENV:Header>
*     <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
*         <z:FooBar xmlns:z="http://example.com"/>
*     </SOAP-ENV:Body>
* </SOAP-ENV:Envelope>

* -----------------------------------------------------------------------------------------
* There are a number of ways we can get the contents of the  <ds:SignatureValue>...</ds:SignatureValue>

lcFilePath = "qa_data/xml_dsig_testing/sample_to_show_how_to_extract_sig.xml"

* If you know there will only be a single SignatureValue in the XML, you don't need to parse XML.
* Just do quick and simple string search..
* For example:
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSb = CreateObject('Chilkat.StringBuilder')
lnSuccess = loSb.LoadFile(lcFilePath,"utf-8")
IF (lnSuccess = 0) THEN
    ? "Failed to load file."
    RELEASE loSb
    CANCEL
ENDIF

lcBase64Sig = loSb.GetBetween("SignatureValue>","</")
? "base64Sig = " + lcBase64Sig

* -----------------------------------------------------------------------------------------
* If the XML might contain multiple signatures, but the signatures will always be located in the 
* same place, then you can (beforehand) copy a sample signed XML into Chilkat's online tool
* at Generate Parsing Code from XML
* to get the path to the SignatureValue.  For example, the line of code generated for the SignatureValue
* for the above XML is:
* string ds_SignatureValue = xml.GetChildContent("SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue");

* So you can simply use that path..
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Xml')
loXml = CreateObject('Chilkat.Xml')
lnSuccess = loXml.LoadXmlFile(lcFilePath)
* Assume success..

lcBase64Sig = loXml.GetChildContent("SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue")
? "base64Sig = " + lcBase64Sig

* -----------------------------------------------------------------------------------------
* Or perhaps you don't know where the signature is located in the XML.
* You can search for the tag..
loXSigVal = loXml.SearchForTag(loXml,"*:SignatureValue")
IF (loXml.LastMethodSuccess = 1) THEN
    ? "base64Sig = " + loXSigVal.Content
    RELEASE loXSigVal
ELSE
    ? "No SignatureValue found."
ENDIF

RELEASE loSb
RELEASE loXml