(Delphi ActiveX) Verify Opaque Signature and Retrieve Signing Certificates

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign.

Note: This example requires Chilkat v11.0.0 or greater.

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
crypt: TChilkatCrypt2;
binData: TChilkatBinData;
cert: TChilkatCert;
certChain: TChilkatCertChain;
numCerts: Integer;
i: Integer;

begin
success := 0;

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

crypt := TChilkatCrypt2.Create(Self);

// Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
success := crypt.VerifyP7M('qa_data/p7m/opaqueSig.p7','qa_output/originalData.dat');
if (success = 0) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// Alternatively, we can do it in memory...
binData := TChilkatBinData.Create(Self);
success := binData.LoadFile('qa_data/p7m/opaqueSig.p7');
// Your app should check for success, but we'll skip the check for brevity..

// If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
success := crypt.OpaqueVerifyBd(binData.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// For our testing, we signed some text, so we can get it from the binData..
Memo1.Lines.Add('Original Data:');
Memo1.Lines.Add(binData.GetString('utf-8'));

// After any method call that verifies a signature, the crypt object will contain the certificate(s)
// that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

// Get each signing certificate, and build the certificate chain for each.
cert := TChilkatCert.Create(Self);
certChain := TChilkatCertChain.Create(Self);
numCerts := crypt.NumSignerCerts;
i := 0;
while i < numCerts do
  begin
    crypt.LastSignerCert(i,cert.ControlInterface);
    Memo1.Lines.Add(cert.SubjectDN);

    success := cert.BuildCertChain(certChain.ControlInterface);
    if (success = 0) then
      begin
        Memo1.Lines.Add(cert.LastErrorText);
        Exit;
      end;

    i := i + 1;
  end;
end;