Delphi ActiveX

ECDSA Sign Data and Verify Signature

See more ECC Examples

Demonstrates using the Elliptic Curve Digital Signature Algorithm to hash data and sign it. Also demonstrates how to verify the ECDSA signature. Delphi ActiveX

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
success: Integer;
crypt: TChilkatCrypt2;
hash1: WideString;
hash2: WideString;
privKey: TPrivateKey;
prng: TChilkatPrng;
ecdsa: TChilkatEcc;
ecdsaSigBase64: WideString;
pubKey: TPublicKey;
result: Integer;

begin
success := 0;

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

// To create an ECDSA signature, the data first needs to be hashed.  Then the hash
// is signed.

// Use Chilkat Crypt2 to generate a hash for any of the following
// hash algorithms: SHA256, SHA384, SHA512, SHA1, MD5, MD2, HAVAL, RIPEMD128/160/256/320

crypt := TChilkatCrypt2.Create(Self);
crypt.HashAlgorithm := 'SHA256';
crypt.Charset := 'utf-8';
crypt.EncodingMode := 'base64';

// Hash a string.
hash1 := crypt.HashStringENC('The quick brown fox jumps over the lazy dog');
Memo1.Lines.Add('hash1 = ' + hash1);

// Or hash a file..
hash2 := crypt.HashFileENC('qa_data/hamlet.xml');
Memo1.Lines.Add('hash2 = ' + hash2);

// (The Crypt2 API provides many other ways to hash data..)

// -----------------------------------------------------------
// An ECDSA private key is used for signing.  The public key is for signature verification.
// Load our ECC private key.
// Our private key file contains this:

// 	// -----BEGIN PRIVATE KEY-----
// 	MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg3J8q/24D1sEKGdP9
// 	72MGYElLGpw/a56Y3t6pfON3uhShRANCAATlSmoizyhAwoYZAOuFBATl07/1RR54
// 	a1Dzfm16grxJe666AGKR+bSs24hk7TEpaeCTvT8YOOM3l+xKFg7zq6Q9
// 	-----END PRIVATE KEY-----

privKey := TPrivateKey.Create(Self);
success := privKey.LoadPemFile('qa_data/ecc/secp256r1-key-pkcs8.pem');
if (success <> 1) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

// We'll need a PRNG source for random number generation.
// Use Chilkat's PRNG (for the Fortuna PRNG algorithm).
prng := TChilkatPrng.Create(Self);

// Sign the hash..
ecdsa := TChilkatEcc.Create(Self);
ecdsaSigBase64 := ecdsa.SignHashENC(hash1,'base64',privKey.ControlInterface,prng.ControlInterface);
if (ecdsa.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(ecdsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('ECDSA signature = ' + ecdsaSigBase64);

// -----------------------------------------------------------
// Now let's verify the signature using the public key.

pubKey := TPublicKey.Create(Self);
success := pubKey.LoadFromFile('qa_data/ecc/secp256r1-pubkey.pem');
if (success <> 1) then
  begin
    Memo1.Lines.Add(pubKey.LastErrorText);
    Exit;
  end;

result := ecdsa.VerifyHashENC(hash1,ecdsaSigBase64,'base64',pubKey.ControlInterface);
if (result = 1) then
  begin
    Memo1.Lines.Add('Signature is valid.');
    Exit;
  end;
if (result = 0) then
  begin
    Memo1.Lines.Add('Signature is invalid.');
    Exit;
  end;
if (result < 0) then
  begin
    Memo1.Lines.Add(ecdsa.LastErrorText);
    Memo1.Lines.Add('The VerifyHashENC method call failed.');
    Exit;
  end;
end;