(Delphi ActiveX) JWE using RSAES-PKCS1-v1_5 and AES_128_CBC_HMAC_SHA_256

This example duplicates the example A.2 in RFC 7516 for JSON Web Encryption (JWE).

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;
plaintext: WideString;
jweProtHdr: TChilkatJsonObject;
sbJwk: TChilkatStringBuilder;
rsaPrivKey: TPrivateKey;
rsaPubKey: IPublicKey;
jwe: TChilkatJwe;
strJwe: WideString;
jwe2: TChilkatJwe;
originalPlaintext: WideString;
sbJwe: 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.

plaintext := 'Live long and prosper.';

// First build the JWE Protected Header.
// We want to build this: {"alg":"RSA1_5","enc":"A128CBC-HS256"}
jweProtHdr := TChilkatJsonObject.Create(Self);
jweProtHdr.AppendString('alg','RSA1_5');
jweProtHdr.AppendString('enc','A128CBC-HS256');
Memo1.Lines.Add('JWE Protected Header: ' + jweProtHdr.Emit());
Memo1.Lines.Add('--');

// The specific RSA key used in the A.2 example is the following JWK:
sbJwk := TChilkatStringBuilder.Create(Self);
sbJwk.Append('{"kty":"RSA",');
sbJwk.Append('"n":"sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl');
sbJwk.Append('UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre');
sbJwk.Append('cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_');
sbJwk.Append('7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI');
sbJwk.Append('Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU');
sbJwk.Append('7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw",');
sbJwk.Append('"e":"AQAB",');
sbJwk.Append('"d":"VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq');
sbJwk.Append('1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry');
sbJwk.Append('nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_');
sbJwk.Append('0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj');
sbJwk.Append('-VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj');
sbJwk.Append('T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ",');
sbJwk.Append('"p":"9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68');
sbJwk.Append('ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP');
sbJwk.Append('krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM",');
sbJwk.Append('"q":"uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y');
sbJwk.Append('BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN');
sbJwk.Append('-3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0",');
sbJwk.Append('"dp":"w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv');
sbJwk.Append('ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra');
sbJwk.Append('Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs",');
sbJwk.Append('"dq":"o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff');
sbJwk.Append('7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_');
sbJwk.Append('odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU",');
sbJwk.Append('"qi":"eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC');
sbJwk.Append('tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ');
sbJwk.Append('B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo"');
sbJwk.Append('}');

// Load this JWK into a Chilkat private key object.
rsaPrivKey := TPrivateKey.Create(Self);
success := rsaPrivKey.LoadJwk(sbJwk.GetAsString());
if (success <> 1) then
  begin
    Memo1.Lines.Add(rsaPrivKey.LastErrorText);
    Exit;
  end;

// The public key is used to encrypt (i.e. create the JWE), 
// and the private key is used to decrypt.
// The RSA public key is simply a subset of the private key.  The RSA public key
// is composed of the "n" and "e" members shown above.  These are also known as the
// modulus and exponent.
// We can simply get the public key object from the private key object
rsaPubKey := rsaPrivKey.GetPublicKey();

// Create the JWE...
jwe := TChilkatJwe.Create(Self);
jwe.SetProtectedHeader(jweProtHdr.ControlInterface);
jwe.SetPublicKey(0,rsaPubKey);

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);

// Note: The RSA PKCS1_V1_5 padding uses random value, and the results
// will be different each time.  However, each result should be successfully
// decrypting if using the correct RSA private key.

// Let's decrypt the JWE that was just produced.
// Do the following to decrypt a JWE:
// 1) Load the JWE.
// 2) Set the private key for decryption.
// 3) Decrypt.
jwe2 := TChilkatJwe.Create(Self);
success := jwe2.LoadJwe(strJwe);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;

// Provide the RSA private key for decryption.
// (The JWE was encrypted for a single recipient at index 0.)
jwe2.SetPrivateKey(0,rsaPrivKey.ControlInterface);

// 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);

// ---------------------------------------------------------------------------------
// It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.2.7
// because it was produced using the same RSA key.

sbJwe := TChilkatStringBuilder.Create(Self);
sbJwe.Append('eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.');
sbJwe.Append('UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm');
sbJwe.Append('1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc');
sbJwe.Append('HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF');
sbJwe.Append('NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8');
sbJwe.Append('rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv');
sbJwe.Append('-B3oWh2TbqmScqXMR4gp_A.');
sbJwe.Append('AxY8DCtDaGlsbGljb3RoZQ.');
sbJwe.Append('KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.');
sbJwe.Append('9hH0vgRfYgPnAHOd8stkvw');

success := jwe2.LoadJweSb(sbJwe.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;

// Provide the RSA private key for decryption.
jwe2.SetPrivateKey(0,rsaPrivKey.ControlInterface);

// Decrypt.
originalPlaintext := jwe2.Decrypt(0,'utf-8');
if (jwe2.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(jwe2.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add(originalPlaintext);
end;