(Delphi DLL) RSA Hash Binary Data and Sign (and Verify)

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, BinData, PrivateKey, Rsa, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
privKey: HCkPrivateKey;
rsa: HCkRsa;
originalData: PWideChar;
bdData: HCkBinData;
bdSignature: HCkBinData;
pubKey: HCkPublicKey;
rsa2: HCkRsa;
bVerified: Boolean;

begin
success := False;

// 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 := CkPrivateKey_Create();
success := CkPrivateKey_LoadEncryptedPemFile(privKey,'qa_data/pem/rsa_passwd.pem','passwd');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

rsa := CkRsa_Create();
CkRsa_UsePrivateKey(rsa,privKey);

// We have some binary data (in hex) to sign
originalData := '0102030405060708090A';
bdData := CkBinData_Create();
CkBinData_AppendEncoded(bdData,originalData,'hex');

// Hash (SHA-256) and sign the hash:
bdSignature := CkBinData_Create();
success := CkRsa_SignBd(rsa,bdData,'sha256',bdSignature);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

// Show the RSA signature in base64
Memo1.Lines.Add(CkBinData__getEncoded(bdSignature,'base64'));

// ------------------------------------------
// Get the public key from the private key
pubKey := CkPublicKey_Create();
CkPrivateKey_ToPublicKey(privKey,pubKey);

// Verify the signature..
rsa2 := CkRsa_Create();
CkRsa_UsePublicKey(rsa2,pubKey);

bVerified := CkRsa_VerifyBd(rsa2,bdData,'sha256',bdSignature);
Memo1.Lines.Add('signature verified: ' + IntToStr(Ord(bVerified)));

CkPrivateKey_Dispose(privKey);
CkRsa_Dispose(rsa);
CkBinData_Dispose(bdData);
CkBinData_Dispose(bdSignature);
CkPublicKey_Dispose(pubKey);
CkRsa_Dispose(rsa2);

end;