Lazarus Pascal

Set the DKIM Signing Private Key

Demonstrates the Chilkat Dkim.SetDkimPrivateKey method, which supplies the RSA private key used by DkimSign. The only argument is a PrivateKey object. The source key may be destroyed after this returns, and the configured key can be reused for multiple signatures.

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: DKIM proves a message really came from its domain by signing it with a private key that only the domain owner holds; recipients verify with the matching public key published in the domain's DNS. This method loads that private half into the Dkim object once, so a mail server can sign every outgoing message without re-reading the key each time. Because the key is the domain's signing secret, it should be protected like any other private key and never committed to source.

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Lazarus Pascal

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.PrivateKey,
  Chilkat.Dkim;

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

procedure RunDemo;
var
  success: Boolean;
  dkim: TDkim;
  privKey: TPrivateKey;

begin
  success := False;

  //  Demonstrates the Dkim.SetDkimPrivateKey method, which supplies the RSA private key used by
  //  DkimSign.  The only argument is a PrivateKey object.

  dkim := TDkim.Create;

  //  Load the RSA private key that corresponds to the public key published in the domain's DNS.
  privKey := TPrivateKey.Create;
  success := privKey.LoadPemFile('qa_data/dkim_private.pem');
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  //  Copy the key into the Dkim object.  The PrivateKey object may be destroyed afterward, and the
  //  configured key can be reused for multiple signatures.
  success := dkim.SetDkimPrivateKey(privKey);
  if (success = False) then
    begin
      WriteLn(dkim.LastErrorText);
      Exit;
    end;
  WriteLn('DKIM private key configured.');


  dkim.Free;
  privKey.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.