Pascal (Lazarus/Delphi)

Get the S/MIME Signer's Certificate

Demonstrates the Chilkat Mime.LastSignerCert method, which loads the signer certificate at a zero-based index from the most recent successful verification (or security-unwrapping) into a Cert. The first argument is the signer index and the second is the receiving Cert.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Verifying tells you the signature is mathematically valid, but you usually also need to know who signed — the subject, the issuer, the validity dates — to decide whether to trust it. This retrieves each signer's certificate after verification so your code can inspect and apply its own trust rules. A message can have multiple signers, so iterate from 0 to NumSignerCerts - 1.

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Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Cert,
  Chilkat.Mime;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  mime: TMime;
  n: Integer;
  cert: TCert;
  i: Integer;

begin
  success := False;

  mime := TMime.Create;
  success := mime.LoadMimeFile('qa_data/signed.eml');
  if (success = False) then
    begin
      WriteLn(mime.LastErrorText);
      Exit;
    end;

  //  After a successful verification, load each signer's certificate to inspect it.  The 1st argument
  //  is the zero-based signer index and the 2nd is a Cert object that receives the certificate.
  success := mime.Verify();
  if (success <> True) then
    begin
      WriteLn(mime.LastErrorText);
      Exit;
    end;

  n := mime.NumSignerCerts;
  cert := TCert.Create;

  for i := 0 to n - 1 do
    begin
      success := mime.LastSignerCert(i,cert);
      if (success = False) then
        begin
          WriteLn(mime.LastErrorText);
          Exit;
        end;
      WriteLn('Signer ' + i + ': ' + cert.SubjectCN + ' (issued by ' + cert.IssuerCN + ')');
    end;



  mime.Free;
  cert.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.