Delphi ActiveX Requires Chilkat v11.0.0+

About RSA Public/Private Keys

See more RSA Examples

This example provides some additional information for understanding public/private key pairs. In demonstrates how a private key is a superset of the public key. A public key contains the modulus and exponent. The matching private key also contains the modulus and exponent, but also contains the additional private key parts. Delphi ActiveX

var
success: Integer;
cert: TChilkatCert;
pubKey: TPublicKey;
privKey: TPrivateKey;

begin
success := 0;

cert := TChilkatCert.Create(Self);

//  Load a digital certificate.
success := cert.LoadFromFile('digitalCert.cer');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  A .cer file does not contain the private key.  It should contain
//  the public key...
pubKey := TPublicKey.Create(Self);
cert.GetPublicKey(pubKey.ControlInterface);

//  Let's have a look at it (in XML format).
Memo1.Lines.Add('Public Key from Certificate:');
Memo1.Lines.Add(pubKey.GetXml());

//  An RSA public key consists of a modulus and exponent.

//  An RSA private key includes both the modulus and exponent,
//  as well as other "big" numbers: P, Q, D, etc.

//  Let's load an RSA private key from a DER-encoded file:
privKey := TPrivateKey.Create(Self);

success := privKey.LoadAnyFormatFile('PrivateKey.key','');
if (success <> 1) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

//  If this private key is the matching half to the public key from
//  the certificate, then the modulus and exponent should
//  be identical.  (Thus, a "private key" really contains both the public part as well as the private parts...).
Memo1.Lines.Add('Private Key from DER:');
Memo1.Lines.Add(privKey.GetXml());