Pascal (Lazarus/Delphi)

JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

See more JSON Web Encryption (JWE) Examples

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

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.StringBuilder,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  plaintext: string;
  jwe: TJwe;
  jweProtHdr: TJsonObject;
  aesWrappingKey: string;
  strJwe: string;
  jwe2: TJwe;
  originalPlaintext: string;
  sbJwe: TStringBuilder;

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

  WriteLn('JWE Protected Header: ' + jweProtHdr.Emit());
  WriteLn('--');

  //  The example A.3 in RFC 7516 uses the following 128-bit AES key,
  //  specified in JWK (JSON Web Key) format:
  //       {"kty":"oct",
  //        "k":"GawgguFyGrWKav7AX4VKUg"
  //       }
  //  This is just a way of saying: The key type ("kty") is 
  //  a bunch of octets ("k") in base64url encoding.
  //  We can simply set the AES wrapping key like this:
  aesWrappingKey := 'GawgguFyGrWKav7AX4VKUg';
  jwe.SetWrappingKey(0,aesWrappingKey,'base64url');

  //  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 that was just produced.
  //  1) Load the JWE.
  //  2) Set the AES wrapping key.
  //  3) Decrypt.
  jwe2 := TJwe.Create;
  success := jwe2.LoadJwe(strJwe);
  if (success <> True) then
    begin
      WriteLn(jwe2.LastErrorText);
      Exit;
    end;
  //  Set the AES wrap key.
  jwe2.SetWrappingKey(0,aesWrappingKey,'base64url');

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

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

  //  ---------------------------------------------------------------------------------
  //  It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
  //  because it was produced using the same AES Wrap key.

  sbJwe := TStringBuilder.Create;
  sbJwe.Append('eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.');
  sbJwe.Append('6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.');
  sbJwe.Append('AxY8DCtDaGlsbGljb3RoZQ.');
  sbJwe.Append('KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.');
  sbJwe.Append('U0m_YmjN04DJvceFICbCVQ');

  success := jwe2.LoadJweSb(sbJwe);
  if (success <> True) then
    begin
      WriteLn(jwe2.LastErrorText);
      Exit;
    end;

  jwe2.SetWrappingKey(0,aesWrappingKey,'base64url');

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

  WriteLn(originalPlaintext);


  jwe.Free;
  jweProtHdr.Free;
  jwe2.Free;
  sbJwe.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.