Delphi ActiveX Requires Chilkat v11.0.0+

RSA Sign with PKCS8 Encrypted Key

See more RSA Examples

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Delphi ActiveX

var
success: Integer;
privKey: TPrivateKey;
rsa: TChilkatRsa;
strData: WideString;
hexSig: WideString;
cert: TChilkatCert;
pubKey: TPublicKey;
rsa2: TChilkatRsa;

begin
success := 0;

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

privKey := TPrivateKey.Create(Self);

//  Load the private key from an RSA PEM file:
success := privKey.LoadAnyFormatFile('raul_privateKey.key','a0123456789');
if (success = 0) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

rsa := TChilkatRsa.Create(Self);

//  Import the private key into the RSA component:
success := rsa.UsePrivateKey(privKey.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

//  This example will sign a string, and receive the signature
//  in a hex-encoded string.  Therefore, set the encoding mode
//  to "hex":
rsa.EncodingMode := 'hex';

strData := 'This is the string to be signed.';

//  Sign the string using the sha256 hash algorithm.
//  Other valid choices are sha1, sha384, sha512 and others.
hexSig := rsa.SignStringENC(strData,'sha256');
if (rsa.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add(hexSig);

//  Now verify with the public key.
//  This example shows how to use the public key from 
//  a digital certificate (.cer file)
cert := TChilkatCert.Create(Self);
success := cert.LoadFromFile('raul_publicKey.cer');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

pubKey := TPublicKey.Create(Self);
cert.GetPublicKey(pubKey.ControlInterface);

rsa2 := TChilkatRsa.Create(Self);
success := rsa2.UsePublicKey(pubKey.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(rsa2.LastErrorText);
    Exit;
  end;

//  Verify the signature against the original data:
rsa2.EncodingMode := 'hex';
success := rsa2.VerifyStringENC(strData,'sha256',hexSig);
if (success = 0) then
  begin
    Memo1.Lines.Add(rsa2.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Signature verified!');

//  Verify with incorrect data:
success := rsa2.VerifyStringENC('something else','sha256',hexSig);
if (success <> 1) then
  begin
    Memo1.Lines.Add('Signature not verified! (which was expected in this case)');
  end
else
  begin
    Memo1.Lines.Add('Hmmm... that''s not right...');
  end;