Pascal (Lazarus/Delphi)

JWE with Binary Data

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create a JWE that contains a binary payload (such as a JPG image).

Note: This example requires Chilkat v9.5.0.66 or greater.

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.Jwe,
  Chilkat.BinData,
  Chilkat.StringBuilder,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  jpgBytes: TBinData;
  jwe: TJwe;
  jweProtHdr: TJsonObject;
  aesWrappingKey: string;
  sbJwe: TStringBuilder;
  jwe2: TJwe;
  jpgOriginal: TBinData;

begin
  success := False;

  //  This requires the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  //  Note: This example requires Chilkat v9.5.0.66 or greater.

  //  Load a JPG file that will be the JWE payload.
  jpgBytes := TBinData.Create;
  success := jpgBytes.LoadFile('qa_data/jpg/starfish.jpg');
  //  Make sure your app checks the success/failure of the call to LoadFile..
  WriteLn('Original JPG size = ' + jpgBytes.NumBytes);

  jwe := TJwe.Create;

  jweProtHdr := TJsonObject.Create;
  jweProtHdr.AppendString('alg','A128KW');
  jweProtHdr.AppendString('enc','A128CBC-HS256');
  jwe.SetProtectedHeader(jweProtHdr);

  aesWrappingKey := 'GawgguFyGrWKav7AX4VKUg';
  jwe.SetWrappingKey(0,aesWrappingKey,'base64url');

  //  Encrypt and return the JWE in sbJwe:
  sbJwe := TStringBuilder.Create;
  success := jwe.EncryptBd(jpgBytes,sbJwe);
  if (success <> True) then
    begin
      WriteLn(jwe.LastErrorText);
      Exit;
    end;

  //  Show the JWE:
  WriteLn(sbJwe.GetAsString());
  WriteLn('size of JWE: ' + sbJwe.Length);

  //  ---------------------------------------------------------
  //  Decrypt to get the original JPG file..

  jwe2 := TJwe.Create;
  success := jwe2.LoadJweSb(sbJwe);
  if (success <> True) then
    begin
      WriteLn(jwe2.LastErrorText);
      Exit;
    end;
  //  Set the AES wrap key.
  jwe2.SetWrappingKey(0,aesWrappingKey,'base64url');

  //  Decrypt.
  jpgOriginal := TBinData.Create;
  success := jwe2.DecryptBd(0,jpgOriginal);
  if (success <> True) then
    begin
      WriteLn(jwe2.LastErrorText);
      Exit;
    end;
  WriteLn('Decrypted JPG size = ' + jpgOriginal.NumBytes);

  //  Save the decrypted JPG to a file.
  success := jpgOriginal.WriteFile('qa_output/jwe_decrypted_starfish.jpg');

  WriteLn('success = ' + success);

  //  The output of this program, when tested, was:
  //  Original JPG size = 6229
  //  eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.9YFz_wteV ... 7Et3hKhpxnKEXw
  //  size of JWE: 8473
  //  Decrypted JPG size = 6229
  //  success = True


  jpgBytes.Free;
  jwe.Free;
  jweProtHdr.Free;
  sbJwe.Free;
  jwe2.Free;
  jpgOriginal.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.