The tutorial shows how to create and extract the contents of a .p7m file, load a signing certificate from a .pfx file or Windows registry storage, verify the digital signature, and extract certificates from a .p7m file. The program signs the selected file, adds information about the user's certificate, digital signature, and saves this enveloped-data to a .p7m file. Also, the program can load an enveloped-data from a .p7m file, verify included digital signature, and extract both the signing data and included certificates.

 

The given Delphi program utilizes the TclEncryptor component from the Clever Internet Suite library.

 

 

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procedure TForm1.btnSignClick(Sender: TObject);
var
  src, dst: TStream;
  cert: TclCertificate;
begin
  src := nil;
  dst := nil;
  if (cbCertificate.ItemIndex < 0) then Exit;
  try
    src := TFileStream.Create(edtSourceFile.Text, fmOpenRead or fmShareDenyWrite);
    dst := TFileStream.Create(edtDestinationFile.Text, fmCreate);

    cert := clCertificateStore1.Items[cbCertificate.ItemIndex];
    clEncryptor1.Sign(src, dst, False, True, cert, nil);
    ShowMessage('Done');
  finally
    dst.Free();
    src.Free();
  end;
end;

procedure TForm1.btnLoadCertificateClick(Sender: TObject);
var
 i: Integer;
begin
  clCertificateStore1.Close();
  cbCertificate.Clear();

  case cbCertificateLocation.ItemIndex of
    0: clCertificateStore1.ImportFromPFX(edtCertifFileName.Text, edtCertifPassword.Text);
    1: clCertificateStore1.Open('MY');
  end;

  for i := 0 to clCertificateStore1.Items.Count - 1 do
  begin
    if (clCertificateStore1.Items[i].FriendlyName <> '') then
    begin
      cbCertificate.Items.Add(clCertificateStore1.Items[i].FriendlyName);
    end else
    begin
      cbCertificate.Items.Add(clCertificateStore1.Items[i].IssuedTo);
    end;
  end;

  if (cbCertificate.Items.Count > 0) then
  begin
    cbCertificate.ItemIndex := 0;
  end;
end;

 

procedure TForm1.btnVerifyFileClick(Sender: TObject);
begin
  clEncryptor1.ExtractCertificates(edtSRC.Text);
  if clEncryptor1.ExtractedCertificates.Items.Count > 0 then
  begin
    lbResult.Items.Add(clEncryptor1.ExtractedCertificates.Items[0].IssuedTo);
  end;
  clEncryptor1.VerifyEnveloped(edtSRC.Text, edtDST.Text);
end;

 

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