Delphi DLL

Extract SignatureValue from Signed XML

See more XML Digital Signatures Examples

Demonstrates how to extract the signature value from signed XML. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Xml, StringBuilder;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
filePath: PWideChar;
sb: HCkStringBuilder;
base64Sig: PWideChar;
xml: HCkXml;
xSigVal: HCkXml;

begin
success := False;

// 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>

filePath := '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:
sb := CkStringBuilder_Create();
success := CkStringBuilder_LoadFile(sb,filePath,'utf-8');
if (success = False) then
  begin
    Memo1.Lines.Add('Failed to load file.');
    Exit;
  end;

base64Sig := CkStringBuilder__getBetween(sb,'SignatureValue>','</');
Memo1.Lines.Add('base64Sig = ' + base64Sig);

// -----------------------------------------------------------------------------------------
// 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..
xml := CkXml_Create();
success := CkXml_LoadXmlFile(xml,filePath);
// Assume success..

base64Sig := CkXml__getChildContent(xml,'SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue');
Memo1.Lines.Add('base64Sig = ' + base64Sig);

// -----------------------------------------------------------------------------------------
// Or perhaps you don't know where the signature is located in the XML.
// You can search for the tag..
xSigVal := CkXml_SearchForTag(xml,xml,'*:SignatureValue');
if (CkXml_getLastMethodSuccess(xml) = True) then
  begin
    Memo1.Lines.Add('base64Sig = ' + CkXml__content(xSigVal));
    CkXml_Dispose(xSigVal);
  end
else
  begin
    Memo1.Lines.Add('No SignatureValue found.');
  end;

CkStringBuilder_Dispose(sb);
CkXml_Dispose(xml);

end;