Pascal (Lazarus/Delphi)

ECDSA Sign and Verify Data using Different Hash Algorithms

See more ECC Examples

Demonstrates how to create ECDSA signatures on data using different hash algorithms.

Note: This example requires Chilkat v9.5.0.85 or greater because the SignBd and VerifyBd methods were added in v9.5.0.85.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.BinData,
  Chilkat.PrivateKey,
  Chilkat.Prng,
  Chilkat.Ecc,
  Chilkat.PublicKey;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  privKey: TPrivateKey;
  bd: TBinData;
  ecdsa: TEcc;
  prng: TPrng;
  sig: string;
  pubKey: TPublicKey;
  ecc2: TEcc;
  result: Integer;

begin
  success := False;

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

  //  First load an ECDSA private key to be used for signing.
  privKey := TPrivateKey.Create;
  success := privKey.LoadEncryptedPemFile('qa_data/ecc/secp256r1-key-pkcs8-secret.pem','secret');
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  //  Load some data to be signed.
  bd := TBinData.Create;
  success := bd.LoadFile('qa_data/hamlet.xml');
  if (success = False) then
    begin
      WriteLn('Failed to load file to be hashed.');
      Exit;
    end;

  ecdsa := TEcc.Create;
  prng := TPrng.Create;

  //  Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
  WriteLn('ECDSA signing the sha256 hash of the data...');
  sig := ecdsa.SignBd(bd,'sha256','base64',privKey,prng);
  WriteLn('sig = ' + sig);

  //  Verify the signature against the original data.
  //  (We must use the same hash algorithm that was used when signing.)

  //  Load the public key that corresponds to the private key used for signing.
  pubKey := TPublicKey.Create;
  success := pubKey.LoadFromFile('qa_data/ecc/secp256r1-pub.pem');
  if (success = False) then
    begin
      WriteLn(pubKey.LastErrorText);
      Exit;
    end;

  ecc2 := TEcc.Create;
  result := ecc2.VerifyBd(bd,'sha256',sig,'base64',pubKey);
  if (result <> 1) then
    begin
      WriteLn(ecc2.LastErrorText);
      Exit;
    end;

  WriteLn('Verified!');

  //  ----------------------------------------------------------------------------------------
  //  Let's do the same thing, but with sha384 hashing...

  WriteLn('--------------------------------------------');
  WriteLn('ECDSA signing the sha384 hash of the data...');

  sig := ecdsa.SignBd(bd,'sha384','base64',privKey,prng);
  WriteLn('sig = ' + sig);

  result := ecc2.VerifyBd(bd,'sha384',sig,'base64',pubKey);
  if (result <> 1) then
    begin
      WriteLn(ecc2.LastErrorText);
      Exit;
    end;

  WriteLn('Verified!');


  privKey.Free;
  bd.Free;
  ecdsa.Free;
  prng.Free;
  pubKey.Free;
  ecc2.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.