(Delphi DLL) 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 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, StringBuilder, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sbPlainText: HCkStringBuilder;
bCrLf: Boolean;
line: PWideChar;
jwe: HCkJwe;
jweProtHdr: HCkJsonObject;
aesWrappingKey: PWideChar;
sbJweCompressed: HCkStringBuilder;
sbJweUncompressed: HCkStringBuilder;
jwe2: HCkJwe;
sbOriginalText: HCkStringBuilder;

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 := CkStringBuilder_Create();
bCrLf := True;
line := 'Live long and prosper.';
CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);
CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);
CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);
CkStringBuilder_AppendLine(sbPlainText,line,bCrLf);

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

jwe := CkJwe_Create();

// 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 := CkJsonObject_Create();
CkJsonObject_AppendString(jweProtHdr,'alg','A128KW');
CkJsonObject_AppendString(jweProtHdr,'enc','A128CBC-HS256');
CkJsonObject_AppendString(jweProtHdr,'zip','DEF');
CkJwe_SetProtectedHeader(jwe,jweProtHdr);

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

// Encrypt and return the JWE in sbJweCompressed:
sbJweCompressed := CkStringBuilder_Create();
success := CkJwe_EncryptSb(jwe,sbPlainText,'utf-8',sbJweCompressed);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe));
    Exit;
  end;

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

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

sbJweUncompressed := CkStringBuilder_Create();
success := CkJwe_EncryptSb(jwe,sbPlainText,'utf-8',sbJweUncompressed);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe));
    Exit;
  end;

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

// 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 := CkJwe_Create();
success := CkJwe_LoadJweSb(jwe2,sbJweCompressed);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;
// Set the AES wrap key.
CkJwe_SetWrappingKey(jwe2,0,aesWrappingKey,'base64url');

// Decrypt (also automatically decompresses).
sbOriginalText := CkStringBuilder_Create();
success := CkJwe_DecryptSb(jwe2,0,'utf-8',sbOriginalText);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;

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

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

success := CkJwe_LoadJweSb(jwe2,sbJweUncompressed);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;
// Set the AES wrap key.
CkJwe_SetWrappingKey(jwe2,0,aesWrappingKey,'base64url');

// Decrypt.
CkStringBuilder_Clear(sbOriginalText);
success := CkJwe_DecryptSb(jwe2,0,'utf-8',sbOriginalText);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkJwe__lastErrorText(jwe2));
    Exit;
  end;

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

// ------------------------------------------------
// 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.
// 

CkStringBuilder_Dispose(sbPlainText);
CkJwe_Dispose(jwe);
CkJsonObject_Dispose(jweProtHdr);
CkStringBuilder_Dispose(sbJweCompressed);
CkStringBuilder_Dispose(sbJweUncompressed);
CkJwe_Dispose(jwe2);
CkStringBuilder_Dispose(sbOriginalText);

end;