(Delphi DLL) 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 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, EdDSA, PrivateKey, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
alicePrivKey: PWideChar;
bobPubKey: PWideChar;
privKey: HCkPrivateKey;
success: Boolean;
pubKey: HCkPublicKey;
eddsa: HCkEdDSA;
sharedSecret: PWideChar;

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 := CkPrivateKey_Create();
// 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 := CkPrivateKey_LoadEd25519(privKey,alicePrivKey,'');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

pubKey := CkPublicKey_Create();
success := CkPublicKey_LoadEd25519(pubKey,bobPubKey);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

// Create the shared secret:
eddsa := CkEdDSA_Create();
sharedSecret := CkEdDSA__sharedSecretENC(eddsa,privKey,pubKey,'hexlower');
if (CkEdDSA_getLastMethodSuccess(eddsa) = False) then
  begin
    Memo1.Lines.Add(CkEdDSA__lastErrorText(eddsa));
    Exit;
  end;

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

CkPrivateKey_Dispose(privKey);
CkPublicKey_Dispose(pubKey);
CkEdDSA_Dispose(eddsa);

end;