Delphi DLL

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.

Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, BinData, PrivateKey, Prng, Ecc, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
privKey: HCkPrivateKey;
bd: HCkBinData;
ecdsa: HCkEcc;
prng: HCkPrng;
sig: PWideChar;
pubKey: HCkPublicKey;
ecc2: HCkEcc;
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 := CkPrivateKey_Create();
success := CkPrivateKey_LoadEncryptedPemFile(privKey,'qa_data/ecc/secp256r1-key-pkcs8-secret.pem','secret');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

// Load some data to be signed.
bd := CkBinData_Create();
success := CkBinData_LoadFile(bd,'qa_data/hamlet.xml');
if (success = False) then
  begin
    Memo1.Lines.Add('Failed to load file to be hashed.');
    Exit;
  end;

ecdsa := CkEcc_Create();
prng := CkPrng_Create();

// Sign the sha256 hash of the data.  Return the ECDSA signature in the base64 encoding.
Memo1.Lines.Add('ECDSA signing the sha256 hash of the data...');
sig := CkEcc__signBd(ecdsa,bd,'sha256','base64',privKey,prng);
Memo1.Lines.Add('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 := CkPublicKey_Create();
success := CkPublicKey_LoadFromFile(pubKey,'qa_data/ecc/secp256r1-pub.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

ecc2 := CkEcc_Create();
result := CkEcc_VerifyBd(ecc2,bd,'sha256',sig,'base64',pubKey);
if (result <> 1) then
  begin
    Memo1.Lines.Add(CkEcc__lastErrorText(ecc2));
    Exit;
  end;

Memo1.Lines.Add('Verified!');

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

Memo1.Lines.Add('--------------------------------------------');
Memo1.Lines.Add('ECDSA signing the sha384 hash of the data...');

sig := CkEcc__signBd(ecdsa,bd,'sha384','base64',privKey,prng);
Memo1.Lines.Add('sig = ' + sig);

result := CkEcc_VerifyBd(ecc2,bd,'sha384',sig,'base64',pubKey);
if (result <> 1) then
  begin
    Memo1.Lines.Add(CkEcc__lastErrorText(ecc2));
    Exit;
  end;

Memo1.Lines.Add('Verified!');

CkPrivateKey_Dispose(privKey);
CkBinData_Dispose(bd);
CkEcc_Dispose(ecdsa);
CkPrng_Dispose(prng);
CkPublicKey_Dispose(pubKey);
CkEcc_Dispose(ecc2);

end;