Validate a JWS with a Public Key

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.SetPublicKey, which sets the public key used to validate a signature of a loaded JWS.

The file path is relative to the application's current working directory. An absolute path may also be used. Supply the path appropriate to your own environment.

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.Jws,
  Chilkat.PublicKey;

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

procedure RunDemo;
var
  success: Boolean;
  jws: TJws;
  jwsCompact: string;
  pubKey: TPublicKey;
  v: Integer;

begin
  success := False;

  jws := TJws.Create;

  //  Load the JWS compact serialization.
  jwsCompact := 'eyJhbGciOiJIUzI1NiJ9.VGhpcyBpcyB0aGUgY29udGVudCB0byBzaWduLg.<signature>';
  success := jws.LoadJws(jwsCompact);
  if (success = False) then
    begin
      WriteLn(jws.LastErrorText);
      Exit;
    end;

  //  The file path is relative to the application's current working directory.  An absolute path
  //  may also be used.  Supply the path appropriate to your own environment.
  //  Load the signer's public key and set it for validating signature 0.
  pubKey := TPublicKey.Create;
  success := pubKey.LoadFromFile('qa_data/signer_pubkey.pem');
  if (success = False) then
    begin
      WriteLn(pubKey.LastErrorText);
      Exit;
    end;
  success := jws.SetPublicKey(0,pubKey);
  if (success = False) then
    begin
      WriteLn(jws.LastErrorText);
      Exit;
    end;

  //  Validate the signature.  Validate returns 1 when valid, 0 when not, or a negative value on error.
  v := jws.Validate(0);
  if (v < 0) then
    begin
      WriteLn(jws.LastErrorText);
      Exit;
    end;
  if (v <> 1) then
    begin
      WriteLn('The signature is not valid.');
      Exit;
    end;
  WriteLn('The signature is valid.');


  jws.Free;
  pubKey.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.