(Delphi ActiveX) JWE with DEFLATE Compression

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

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

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;
sbPlainText: TChilkatStringBuilder;
bCrLf: Integer;
line: WideString;
jwe: TChilkatJwe;
jweProtHdr: TChilkatJsonObject;
aesWrappingKey: WideString;
sbJweCompressed: TChilkatStringBuilder;
sbJweUncompressed: TChilkatStringBuilder;
jwe2: TChilkatJwe;
sbOriginalText: TChilkatStringBuilder;

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.

// Create some plaintext to be encrypted.
// This example will demonstrate with and without DEFLATE (zip) compression.
sbPlainText := TChilkatStringBuilder.Create(Self);
bCrLf := 1;
line := 'Live long and prosper.';
sbPlainText.AppendLine(line,bCrLf);
sbPlainText.AppendLine(line,bCrLf);
sbPlainText.AppendLine(line,bCrLf);
sbPlainText.AppendLine(line,bCrLf);

// The text to be encrypted:
Memo1.Lines.Add(sbPlainText.GetAsString());

jwe := TChilkatJwe.Create(Self);

// Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
// The "zip":"DEF" parameter indicates that the plaintext payload should
// be compressed prior to encryption.
jweProtHdr := TChilkatJsonObject.Create(Self);
jweProtHdr.AppendString('alg','A128KW');
jweProtHdr.AppendString('enc','A128CBC-HS256');
jweProtHdr.AppendString('zip','DEF');
jwe.SetProtectedHeader(jweProtHdr.ControlInterface);

// Set the AES key wrap key:
aesWrappingKey := 'GawgguFyGrWKav7AX4VKUg';
jwe.SetWrappingKey(0,aesWrappingKey,'base64url');

// Encrypt and return the JWE in sbJweCompressed:
sbJweCompressed := TChilkatStringBuilder.Create(Self);
success := jwe.EncryptSb(sbPlainText.ControlInterface,'utf-8',sbJweCompressed.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe.LastErrorText);
    Exit;
  end;

// Show the compressed JWE:
Memo1.Lines.Add(sbJweCompressed.GetAsString());
Memo1.Lines.Add('size of compressed JWE: ' + IntToStr(sbJweCompressed.Length));

// Now create a JWE without compression.
jweProtHdr.Delete('zip');
// Make sure to update the shared protected header:
jwe.SetProtectedHeader(jweProtHdr.ControlInterface);

sbJweUncompressed := TChilkatStringBuilder.Create(Self);
success := jwe.EncryptSb(sbPlainText.ControlInterface,'utf-8',sbJweUncompressed.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe.LastErrorText);
    Exit;
  end;

// Show the uncompressed JWE:
Memo1.Lines.Add(sbJweUncompressed.GetAsString());
Memo1.Lines.Add('size of uncompressed JWE: ' + IntToStr(sbJweUncompressed.Length));

// Decrypting is the same whether compression is used or not.
// The "zip" header in the JWE indicates that the payload should be 
// automatically decompressed (inflated) after decrypting.
jwe2 := TChilkatJwe.Create(Self);
success := jwe2.LoadJweSb(sbJweCompressed.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;
// Set the AES wrap key.
jwe2.SetWrappingKey(0,aesWrappingKey,'base64url');

// Decrypt (also automatically decompresses).
sbOriginalText := TChilkatStringBuilder.Create(Self);
success := jwe2.DecryptSb(0,'utf-8',sbOriginalText.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('original text from compressed JWE: ');
Memo1.Lines.Add(sbOriginalText.GetAsString());

// -----------------------------------------------------------
// Do the same with the uncompressed JWE

success := jwe2.LoadJweSb(sbJweUncompressed.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;
// Set the AES wrap key.
jwe2.SetWrappingKey(0,aesWrappingKey,'base64url');

// Decrypt.
sbOriginalText.Clear();
success := jwe2.DecryptSb(0,'utf-8',sbOriginalText.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('original text from uncompressed JWE: ');
Memo1.Lines.Add(sbOriginalText.GetAsString());

// ------------------------------------------------
// The output of this example is:
// (Note: Your output data will be different because the content encryption key is randomly generated.)

// eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
// size of compressed JWE: 212
// eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
// size of uncompressed JWE: 303
// original text from compressed JWE: 
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// 
// original text from uncompressed JWE: 
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// Live long and prosper.
// 
end;