Delphi DLL

Create XML Signature with External Data Reference

See more XML Digital Signatures Examples

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.

Delphi 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
success: Boolean;
url: PWideChar;
http: HCkHttp;
sbXml: HCkStringBuilder;
rsaKey: HCkPrivateKey;
xmlSigGen: HCkXmlDSigGen;
jpgUrl: PWideChar;
jpgData: HCkBinData;

begin
success := False;

// 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;