(Delphi ActiveX) Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card.

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
cert: TChilkatCert;
success: Integer;
privKey: IPrivateKey;
jwsProtHdr: TChilkatJsonObject;
jws: TChilkatJws;
signatureIndex: Integer;
bIncludeBom: Integer;
payloadStr: WideString;
jwsCompact: WideString;
jws2: TChilkatJws;
rsaPubKey: IPublicKey;
v: Integer;
joseHeader: IChilkatJsonObject;

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

// Load the certificate from a smart card.
cert := TChilkatCert.Create(Self);
success := cert.LoadFromSmartcard('');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

// Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
// such as selecting a certificate if the card contains multiple certificates with private keys,
// or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

// If the associated private key was present on the smartcard, then you can simply
// get it from the Chilkat cert object:
privKey := cert.ExportPrivateKey();
if (cert.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

// You can check the key type to make sure it's RSA.
// This will output "rsa" if the key is RSA.
Memo1.Lines.Add('Key type = ' + privKey.KeyType);

// Create the JWS Protected Header
jwsProtHdr := TChilkatJsonObject.Create(Self);
jwsProtHdr.AppendString('alg','RS256');

jws := TChilkatJws.Create(Self);

// Set the protected header:
signatureIndex := 0;
jws.SetProtectedHeader(signatureIndex,jwsProtHdr.ControlInterface);

// Set the RSA key:
jws.SetPrivateKey(signatureIndex,privKey);

// Set the payload.
bIncludeBom := 0;
payloadStr := 'In our village, folks say God crumbles up the old moon into stars.';
jws.SetPayload(payloadStr,'utf-8',bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
jwsCompact := jws.CreateJws();
if (jws.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(jws.LastErrorText);

    Exit;
  end;

Memo1.Lines.Add('JWS: ' + jwsCompact);

// sample output:
// JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

// Now load the JWS, validate, and recover the original text.
jws2 := TChilkatJws.Create(Self);

// Load the JWS.
success := jws2.LoadJws(jwsCompact);

rsaPubKey := privKey.GetPublicKey();

// Set the RSA public key used for validation.
signatureIndex := 0;
jws2.SetPublicKey(signatureIndex,rsaPubKey);

// Validate the 1st (and only) signature at index 0..
v := jws2.Validate(signatureIndex);
if (v < 0) then
  begin
    // Perhaps Chilkat was not unlocked or the trial expired..
    Memo1.Lines.Add('Method call failed for some other reason.');
    Memo1.Lines.Add(jws2.LastErrorText);
    Exit;
  end;
if (v = 0) then
  begin
    Memo1.Lines.Add('Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both.');
    Exit;
  end;

// If we get here, the signature was validated..
Memo1.Lines.Add('Signature validated.');

// Recover the original content:
Memo1.Lines.Add(jws2.GetPayload('utf-8'));

// Examine the protected header:
joseHeader := jws2.GetProtectedHeader(signatureIndex);
if (jws2.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add('No protected header found at the given index.');
    Exit;
  end;
joseHeader.EmitCompact := 0;

Memo1.Lines.Add('Protected (JOSE) header:');
Memo1.Lines.Add(joseHeader.Emit());

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "alg": "RS256"
// 	}
end;