Pascal (Lazarus/Delphi)

Check if an Email Was Received Digitally Signed

Demonstrates the read-only Chilkat Email.ReceivedSigned property, which is true if the email was originally received carrying one or more digital signatures. Knowing a message was signed is separate from knowing the signature checked out, so this example also reads SignaturesValid to report whether the signed content verified.

Background: A digital signature on an email (S/MIME) provides two things: authenticity (it was really sent by the holder of a particular certificate) and integrity (the content was not altered in transit). The sender signs a hash of the message with their private key; the recipient verifies it with the sender's public certificate. ReceivedSigned simply tells you a signature is present — verifying it is a separate step exposed through SignaturesValid.

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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.Email;

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

procedure RunDemo;
var
  success: Boolean;
  email: TEmail;

begin
  success := False;

  //  Demonstrates the read-only Email.ReceivedSigned property, which is true if this
  //  email was originally received with a digital signature.  Use SignaturesValid to
  //  determine whether the signed content actually verified.

  email := TEmail.Create;

  success := email.LoadEml('qa_data/eml/signed.eml');
  if (success = False) then
    begin
      WriteLn(email.LastErrorText);
      Exit;
    end;

  if (email.ReceivedSigned = True) then
    begin
      WriteLn('This email was received with a digital signature.');
      if (email.SignaturesValid = True) then
        begin
          WriteLn('All signatures are valid.');
        end
      else
        begin
          WriteLn('One or more signatures are NOT valid.');
        end;
    end
  else
    begin
      WriteLn('This email was not signed.');
    end;

  //  Note: Paths such as "qa_data/..." are relative local filesystem paths,
  //  relative to the current working directory of the running application.


  email.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.