(Delphi ActiveX) JWE using A256GCMKW

This example demonstrates creating a JCE with AES GCM key wrap.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
plaintext: WideString;
jwe: TChilkatJwe;
jweProtHdr: TChilkatJsonObject;
prng: TChilkatPrng;
aesWrappingKey: WideString;
strJwe: WideString;
jwe2: TChilkatJwe;
originalPlaintext: WideString;

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

plaintext := 'My text to enrypt';

jwe := TChilkatJwe.Create(Self);

// First build the JWE Protected Header: 

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

jweProtHdr := TChilkatJsonObject.Create(Self);
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 := TChilkatPrng.Create(Self);
jweProtHdr.AppendString('iv',prng.RandomString(16,1,1,1));
jwe.SetProtectedHeader(jweProtHdr.ControlInterface);

Memo1.Lines.Add('JWE Protected Header: ' + jweProtHdr.Emit());
Memo1.Lines.Add('--');

// 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 <> 1) then
  begin
    Memo1.Lines.Add(jwe.LastErrorText);
    Exit;
  end;

// Show the JWE we just created:
Memo1.Lines.Add(strJwe);

// Decrypt the JWE that was just produced.
// 1) Load the JWE.
// 2) Set the AES wrapping key.
// 3) Decrypt.
jwe2 := TChilkatJwe.Create(Self);
success := jwe2.LoadJwe(strJwe);
if (success <> 1) then
  begin
    Memo1.Lines.Add(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 <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('original text: ');
Memo1.Lines.Add(originalPlaintext);
end;