(Delphi DLL) JWE using PBES2 Key Wrapping

Demonstrates how to create and decrypt a JWE that using PBES2 key wrapping.

This example demonstrates PBES2 with HMAC SHA-256 and A128KW wrapping. It is also possible to do the following by simply changing the "alg" parameter:

• PBES2 with HMAC SHA-384 and A192KW wrapping
• PBES2 with HMAC SHA-512 and A256KW wrapping

Note: This example requires Chilkat v9.5.0.66 or greater.

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;
recipientIndex: Integer;
strJwe: PWideChar;
jwe2: HCkJwe;
originalPlaintext: PWideChar;

begin
// 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 := CkJwe_Create();

// First build the JWE Protected Header..
jweProtHdr := CkJsonObject_Create();
CkJsonObject_AppendString(jweProtHdr,'alg','PBES2-HS256+A128KW');
CkJsonObject_AppendString(jweProtHdr,'enc','A128GCM');

// PBES2 requires two additional parameters:
// 1) A random salt parameter ("p2s") containing 8 or more bytes in base64url format.
// 2) An iteration count parameter ("p2c").  A minimum count of 1000 is recommended.
//    The iteration count is intended to make the PBES2 computation more expensive (time consuming)
//    to prevent brute-force attacks.
prng := CkPrng_Create();
CkJsonObject_AppendString(jweProtHdr,'p2s',CkPrng__genRandom(prng,16,'base64url'));
CkJsonObject_AppendString(jweProtHdr,'p2c','1000');

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

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

// Set the PBES2 password
recipientIndex := 0;
CkJwe_SetPassword(jwe,recipientIndex,'top secret');

// 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.
jwe2 := CkJwe_Create();
success := CkJwe_LoadJwe(jwe2,strJwe);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;
// Set the PBES2 password
CkJwe_SetPassword(jwe2,recipientIndex,'top secret');

// 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);

// Sample output:

// JWE Protected Header: {"alg":"PBES2-HS256+A128KW","enc":"A128GCM","p2s":"z39rTEfRy1T1Yn_D1mZRlg","p2c":"1000"}
// --
// eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwicDJzIjoiejM5clRFZlJ5MVQxWW5fRDFtWlJsZyIsInAyYyI6IjEwMDAifQ.koYt6PrFmYwcwdcT7ZcvXHA1d-Xez5h4.luGlbvEnZp-7IsBOj42Yhw.YMTcfLf8Qe4zazozGV2OAu3cUdQ8Kg.rWub47ESWkc6IqZJTvSTmg
// original text: 
// Live long and prosper.

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

end;