(Delphi DLL) JWE using A256GCMKW

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

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
plaintext: PWideChar;
jwe: HCkJwe;
jweProtHdr: HCkJsonObject;
prng: HCkPrng;
aesWrappingKey: PWideChar;
strJwe: PWideChar;
jwe2: HCkJwe;
originalPlaintext: PWideChar;

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

plaintext := 'My text to enrypt';

jwe := CkJwe_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 := CkJsonObject_Create();
CkJsonObject_AppendString(jweProtHdr,'alg','A256GCMKW');
// kid is optional
CkJsonObject_AppendString(jweProtHdr,'kid','18ec08e1-bfa9-4d95-b205-2b4dd1d4321d');
// tag is optional
CkJsonObject_AppendString(jweProtHdr,'tag','kfPduVQ3T3H6vnewt--ksw');
CkJsonObject_AppendString(jweProtHdr,'enc','A256GCM');
// the iv should be 16 random chars.
prng := CkPrng_Create();
CkJsonObject_AppendString(jweProtHdr,'iv',CkPrng__randomString(prng,16,True,True,True));
CkJwe_SetProtectedHeader(jwe,jweProtHdr);

Memo1.Lines.Add('JWE Protected Header: ' + CkJsonObject__emit(jweProtHdr));
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';
CkJwe_SetWrappingKey(jwe,0,aesWrappingKey,'ascii');

// Encrypt and return the JWE:
strJwe := CkJwe__encrypt(jwe,plaintext,'utf-8');
if (CkJwe_getLastMethodSuccess(jwe) <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe));
    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 := CkJwe_Create();
success := CkJwe_LoadJwe(jwe2,strJwe);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;
// Set the AES wrap key.  Important to use "ascii"
CkJwe_SetWrappingKey(jwe2,0,aesWrappingKey,'ascii');

// Decrypt.
originalPlaintext := CkJwe__decrypt(jwe2,0,'utf-8');
if (CkJwe_getLastMethodSuccess(jwe2) <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;

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

CkJwe_Dispose(jwe);
CkJsonObject_Dispose(jweProtHdr);
CkPrng_Dispose(prng);
CkJwe_Dispose(jwe2);

end;