Pascal (Lazarus/Delphi)

JWE using A256GCMKW

See more JSON Web Encryption (JWE) Examples

This example demonstrates creating a JCE with AES GCM key wrap. 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.Prng,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  plaintext: string;
  jwe: TJwe;
  jweProtHdr: TJsonObject;
  prng: TPrng;
  aesWrappingKey: string;
  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.

  plaintext := 'My text to enrypt';

  jwe := TJwe.Create;

  //  First build the JWE Protected Header: 

  //          {
  //              "alg": "A256GCMKW",
  //              "kid": "18ec08e1-bfa9-4d95-b205-2b4dd1d4321d",
  //              "tag": "kfPduVQ3T3H6vnewt--ksw",
  //              "iv": "KkYT0GX_2jHlfqN_",
  //              "enc": "A128CBC-HS256"
  //          }

  jweProtHdr := TJsonObject.Create;
  jweProtHdr.AppendString('alg','A256GCMKW');
  //  kid is optional
  jweProtHdr.AppendString('kid','18ec08e1-bfa9-4d95-b205-2b4dd1d4321d');
  //  tag is optional
  jweProtHdr.AppendString('tag','kfPduVQ3T3H6vnewt--ksw');
  jweProtHdr.AppendString('enc','A256GCM');
  //  the iv should be 16 random chars.
  prng := TPrng.Create;
  jweProtHdr.AppendString('iv',prng.RandomString(16,True,True,True));
  jwe.SetProtectedHeader(jweProtHdr);

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

  //  Given that we have 256-bit AES, our key should be 32 bytes.
  //  The ascii string here is 32 bytes, therefore the 2nd arg is "ascii" to use these
  //  ascii chars directly as the key.
  aesWrappingKey := '2baf4f730f5e4542b428593ef9cceb0e';
  jwe.SetWrappingKey(0,aesWrappingKey,'ascii');

  //  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.  Important to use "ascii"
  jwe2.SetWrappingKey(0,aesWrappingKey,'ascii');

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

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


  jwe.Free;
  jweProtHdr.Free;
  prng.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.