(Delphi ActiveX) RSA Sign String using Private Key of Certificate Type A3 (smart card / token)

Demonstrates RSA signing a string using the private key of a certificate type A3 (smart card, token).

Note: This is a Windows-only example.

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
certStore: TChilkatCertStore;
thumbprint: WideString;
bReadOnly: Integer;
success: Integer;
cert: IChilkatCert;
rsa: TChilkatRsa;
bUsePrivateKey: Integer;
sigBase64: WideString;

begin
// First get the A3 certificate that was installed on the Windows system.
certStore := TChilkatCertStore.Create(Self);

thumbprint := '12c1dd8015f3f03f7b1fa619dc24e2493ca8b4b2';

// This is specific to Windows because it is opening the Windows Current-User certificate store.
bReadOnly := 1;
success := certStore.OpenCurrentUserStore(bReadOnly);
if (success <> 1) then
  begin
    Memo1.Lines.Add(certStore.LastErrorText);
    Exit;
  end;

// Find the certificate with the desired thumbprint
// (There are many ways to locate a certificate.  This example chooses to find by thumbprint.)
cert := certStore.FindCertBySha1Thumbprint(thumbprint);
if (certStore.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add('Failed to find the certificate.');
    Exit;
  end;

Memo1.Lines.Add('Found: ' + cert.SubjectCN);

rsa := TChilkatRsa.Create(Self);

// Provide the cert's private key
bUsePrivateKey := 1;
success := rsa.SetX509Cert(cert,bUsePrivateKey);

if (success <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

// Return the RSA signature in base64 encoded form.
rsa.EncodingMode := 'base64';

// Sign the utf-8 byte representation of the string.
rsa.Charset := 'utf-8';

// You can also choose other hash algorithms, such as SHA-1.
sigBase64 := rsa.SignStringENC('text to sign','SHA-256');
if (rsa.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Base64 signature: ' + sigBase64);
end;