Pascal (Lazarus/Delphi)

JWE using "dir" Direct use of Shared Symmetric Key

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create a JWE using the "dir" alg -- which is to directly use a shared symmetric key.

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.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  plaintext: string;
  jwe: TJwe;
  jweProtHdr: TJsonObject;
  recipientIndex: Integer;
  strJwe: string;
  jwe2: TJwe;
  originalPlaintext: string;

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.

  plaintext := 'Live long and prosper.';

  jwe := TJwe.Create;

  //  First build the JWE Protected Header..
  jweProtHdr := TJsonObject.Create;
  jweProtHdr.AppendString('alg','dir');
  jweProtHdr.AppendString('enc','A128GCM');

  //  Don't forget to actually provide the protected header to the JWE object:
  jwe.SetProtectedHeader(jweProtHdr);

  //  The JWE is to use 128-bit AES GCM encryption as specified by the "enc" parameter.
  //  Given that the "alg" = "dir", we are to directly specify the AES GCM key.
  //  (It is assumed that the decrypting side also has knowledge of the direct key to be used..)

  //  Our key will be these 16 hex bytes: 000102030405060708090A0B0C0D0E0F

  //  The SetWrappingKey method is also used for "dir" direct keys.
  //  However, if there are multiple recipients, they must all share the same CEK (Content Encryption Key),
  //  which is specified by calling SetWrappingKey with an index of 0.

  recipientIndex := 0;
  jwe.SetWrappingKey(recipientIndex,'000102030405060708090A0B0C0D0E0F','hex');

  //  Encrypt and return the JWE:
  strJwe := jwe.Encrypt(plaintext,'utf-8');
  if (jwe.LastMethodSuccess <> True) then
    begin
      WriteLn(jwe.LastErrorText);
      Exit;
    end;

  //  Show the JWE we just created:
  WriteLn(strJwe);

  //  Decrypt the JWE.
  jwe2 := TJwe.Create;
  success := jwe2.LoadJwe(strJwe);
  if (success <> True) then
    begin
      WriteLn(jwe2.LastErrorText);
      Exit;
    end;
  jwe2.SetWrappingKey(0,'000102030405060708090A0B0C0D0E0F','hex');

  //  Decrypt.
  originalPlaintext := jwe2.Decrypt(0,'utf-8');
  if (jwe2.LastMethodSuccess <> True) then
    begin
      WriteLn(jwe2.LastErrorText);
      Exit;
    end;

  WriteLn('original text: ');
  WriteLn(originalPlaintext);

  //  Sample output:
  //  eyJhbGciOiJkaXIiLCJlbmMiOiJBMTI4R0NNIn0..20HX5Huc7f1nQC4pBUtiCQ.axFZIxtZy5j0ifJQUzGXLKIpsBuxJA.eBrOC-NrsreN6JeGuOPk1g
  //  original text: 
  //  Live long and prosper.


  jwe.Free;
  jweProtHdr.Free;
  jwe2.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.