(Delphi ActiveX) Ed25519 Key Exchange (Shared Secret)

Demonstrates how to create an Ed25519 shared secret for use in key exchange.

Note: This example requires Chilkat v9.5.0.83 or greater.

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
alicePrivKey: WideString;
bobPubKey: WideString;
privKey: TPrivateKey;
success: Integer;
pubKey: TPublicKey;
eddsa: TChilkatEdDSA;
sharedSecret: WideString;

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

// Alice's private key, a:
//     77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a
// Alice's public key, X25519(a, 9):
//     8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a
// Bob's private key, b:
//     5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb
// Bob's public key, X25519(b, 9):
//     de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f
// Their shared secret, K:
//     4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742

alicePrivKey := '77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a';
bobPubKey := 'de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f';

privKey := TPrivateKey.Create(Self);
// This example shows only one way of loading an Ed25519 private key.
// Chilkat can load other formats (JWK, PEM, ASN.1 DER, etc.)  
// You may do so by calling LoadAnyFormat or LoadAnyFormatFile.
success := privKey.LoadEd25519(alicePrivKey,'');
if (success = 0) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

pubKey := TPublicKey.Create(Self);
success := pubKey.LoadEd25519(bobPubKey);
if (success = 0) then
  begin
    Memo1.Lines.Add(pubKey.LastErrorText);
    Exit;
  end;

// Create the shared secret:
eddsa := TChilkatEdDSA.Create(Self);
sharedSecret := eddsa.SharedSecretENC(privKey.ControlInterface,pubKey.ControlInterface,'hexlower');
if (eddsa.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(eddsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Computed: ' + sharedSecret);
Memo1.Lines.Add('Expected: 4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742');
end;