Delphi DLL

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. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, PublicKey, Jws, Cert, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
cert: HCkCert;
jwsProtHdr: HCkJsonObject;
jws: HCkJws;
signatureIndex: Integer;
bIncludeBom: Boolean;
payloadStr: PWideChar;
jwsCompact: PWideChar;
jws2: HCkJws;
pubKey: HCkPublicKey;
v: Integer;
joseHeader: HCkJsonObject;

begin
success := False;

// 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 := CkCert_Create();

// Set the smarcard PIN prior to loading
CkCert_putSmartCardPin(cert,'123456');

// Detect the connected smartcard or USB security token and load the default certificate.
success := CkCert_LoadFromSmartcard(cert,'');
if (success = False) then
  begin
    Memo1.Lines.Add(CkCert__lastErrorText(cert));
    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).

// Create the JWS Protected Header
jwsProtHdr := CkJsonObject_Create();

if (CkCert_IsEcdsa(cert) = True) then
  begin
    CkJsonObject_AppendString(jwsProtHdr,'alg','ES256');
  end
else
  begin
    CkJsonObject_AppendString(jwsProtHdr,'alg','RS256');
  end;

jws := CkJws_Create();

// Set the protected header:
signatureIndex := 0;
CkJws_SetProtectedHeader(jws,signatureIndex,jwsProtHdr);

// Provide the private key via the certificate.
// This requires Chilkat v11.5.0 or greater.
CkJws_SetSigningCert(jws,signatureIndex,cert);

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

// Create the JWS
// By default, the compact serialization is used.
jwsCompact := CkJws__createJws(jws);
if (CkJws_getLastMethodSuccess(jws) = False) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws));
    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 := CkJws_Create();

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

pubKey := CkPublicKey_Create();
CkCert_GetPublicKey(cert,pubKey);

// Set the public key used for validation.
signatureIndex := 0;
CkJws_SetPublicKey(jws2,signatureIndex,pubKey);

// Validate the 1st (and only) signature at index 0..
v := CkJws_Validate(jws2,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(CkJws__lastErrorText(jws2));
    Exit;
  end;
if (v = 0) then
  begin
    Memo1.Lines.Add('Invalid signature.  The 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(CkJws__getPayload(jws2,'utf-8'));

// Examine the protected header:

joseHeader := CkJsonObject_Create();
success := CkJws_GetProtectedH(jws2,signatureIndex,joseHeader);
if (success = False) then
  begin
    Memo1.Lines.Add(CkJws__lastErrorText(jws2));
    Exit;
  end;

CkJsonObject_putEmitCompact(joseHeader,False);

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

// Output:

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

CkCert_Dispose(cert);
CkJsonObject_Dispose(jwsProtHdr);
CkJws_Dispose(jws);
CkJws_Dispose(jws2);
CkPublicKey_Dispose(pubKey);
CkJsonObject_Dispose(joseHeader);

end;