(Delphi ActiveX) RSA Sign Binary Data and Verify (Recover the Original Data)

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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
privKey: TPrivateKey;
success: Integer;
rsa: TChilkatRsa;
originalData: WideString;
bd: TChilkatBinData;
pubKey: IPublicKey;
rsa2: TChilkatRsa;
bVerified: Integer;

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

// Load an RSA private key for signing.
privKey := TPrivateKey.Create(Self);
success := privKey.LoadEncryptedPemFile('qa_data/pem/rsa_passwd.pem','passwd');
if (success <> 1) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

rsa := TChilkatRsa.Create(Self);
rsa.ImportPrivateKeyObj(privKey.ControlInterface);

// We have some binary data (in hex) to sign
originalData := '0102030405060708090A';
bd := TChilkatBinData.Create(Self);
bd.AppendEncoded(originalData,'hex');

// If successful, the contents of bd are replaced with the RSA signature.
success := rsa.OpenSslSignBd(bd.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

// Show the RSA signature in base64
Memo1.Lines.Add(bd.GetEncoded('base64'));

// ------------------------------------------
// Get the public key from the private key
pubKey := privKey.GetPublicKey();

// Verify the signature and extract the original data.
rsa2 := TChilkatRsa.Create(Self);
rsa2.ImportPublicKeyObj(pubKey);

bVerified := rsa2.OpenSslVerifyBd(bd.ControlInterface);
Memo1.Lines.Add('signature verified: ' + IntToStr(Ord(bVerified)));

// Show the original data:
Memo1.Lines.Add('original data: ' + bd.GetEncoded('hex'));
end;