(Delphi DLL) Create XML Signature with External Data Reference

Demonstrates how to create an XML digital signature where the data is external. In this case, the data is a JPG file.

This example requires Chilkat v9.5.0.69 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, StringBuilder, PrivateKey, XmlDSigGen, BinData;

...

procedure TForm1.Button1Click(Sender: TObject);
var
url: PWideChar;
http: HCkHttp;
sbXml: HCkStringBuilder;
success: Boolean;
rsaKey: HCkPrivateKey;
xmlSigGen: HCkXmlDSigGen;
jpgUrl: PWideChar;
jpgData: HCkBinData;

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

// This example inserts an XML signature in the following XML:

// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <abc>
//   <xyz>
//     <jpg>
//         <name>starfish.jpg</name>
//         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
//     </jpg>
//   </xyz>
// </abc>

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

url := 'https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml';
http := CkHttp_Create();
sbXml := CkStringBuilder_Create();
success := CkHttp_QuickGetSb(http,url,sbXml);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

// We'll use an RSA private key for signing.  
rsaKey := CkPrivateKey_Create();
success := CkPrivateKey_LoadPemFile(rsaKey,'qa_data/rsa/rsaPrivKey_pkcs8.pem');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(rsaKey));
    Exit;
  end;

xmlSigGen := CkXmlDSigGen_Create();

// Indicate were the Signature will be inserted:
CkXmlDSigGen_putSigLocation(xmlSigGen,'abc|xyz|jpg');

// Provide the RSA key to be used for signing:
CkXmlDSigGen_SetPrivateKey(xmlSigGen,rsaKey);

// Fetch the JPG image data.
jpgUrl := 'https://www.chilkatsoft.com/images/starfish.jpg';
jpgData := CkBinData_Create();
success := CkHttp_QuickGetBd(http,jpgUrl,jpgData);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

// Add the external data reference:
CkXmlDSigGen_AddExternalBinaryRef(xmlSigGen,jpgUrl,jpgData,'sha256','');

// Create the XML digital signature:
success := CkXmlDSigGen_CreateXmlDSigSb(xmlSigGen,sbXml);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkXmlDSigGen__lastErrorText(xmlSigGen));
    Exit;
  end;

// Examine the XML that now contains the Signature:
Memo1.Lines.Add(CkStringBuilder__getAsString(sbXml));

// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <abc>
//   <xyz>
//     <jpg>
//         <name>starfish.jpg</name>
//         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
//     <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#rsa-sha256"/><ds:Reference URI="https://www.chilkatsoft.com/images/starfish.jpg"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>AOU810yJV5Np/DnO29qpObqiTSTTCDvxGsX5ayiTYXI=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>ApHRr6nilNrzt3dLveC9zlPoSllaCMfHsbAwr+vYBPkHkJ4wD5LzDDhi1tSJZAAeTckmvSqIG3Wi0rgXQiSM644MD3coBFx4QgrY+GZ+XJJE2Y0Ye3VvaQBiRdUW3INGsW4GLubncgQk5JhuAQjo6O/GKpfEuYqUJj/6CLHLQwMPwbZ2043ykgzuPFoOZf6EydJMBAn1ORMvrpUn+zuA9UngOTGap6eWE4CeiNx23BRC2wSztbUjdCLcqXvgiYu/v0tBNaTcwy7b6+IFtwv/lNUUBUQJ/3p+aErzFn3wLeH3yeqpDCU0U6Dqu5SS1jYupcWWsLHJjYnj2066DPJi/g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:RSAKeyValue><ds:Modulus>sXeRhM55P13FbpNcXAMR3olbw2Wa6keZIHu5YTZYUBTlYWId+pNiwUz3zFIEo+0IfYR0H27ybIycQO+1IIzJofUFNMAL3tZps2OKPlsjuCPls6kXpXhv/gvhux8LrCtp4PcKWqJ6QVOZKChc7WAx40qFWzHi57ueqRTv3x0kESqGg/VjsqyTEvb55psJO2RsfhLT7+YVh3hImRM3RDaJdkTkPuOxeFyT6N7VXD09329sLuS3QkUbE9zEKDnz9X3d8dEQdJhSI9ba5fxl8R7fu8pB67ElfzFml96X1jLFtzy1pzOT5Fc4ROcaqlYckVzdBq9sxezm6MYmDBjNAcibRw==</ds:Modulus><ds:Exponent>AQAB</ds:Exponent></ds:RSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></jpg>
//   </xyz>
// </abc>
// 

CkHttp_Dispose(http);
CkStringBuilder_Dispose(sbXml);
CkPrivateKey_Dispose(rsaKey);
CkXmlDSigGen_Dispose(xmlSigGen);
CkBinData_Dispose(jpgData);

end;