dart-elliptic

In cryptography, the Digital Signature Algorithm (ECDSA) offers a variant of the Digital Signature Algorithm (DSA) which uses elliptic curve cryptography.

This lib mainly defines the abstract class Curve, serving Elliptic Curve which will be used in other packages like ecdsa, schnorr(WIP) and secp256k1 etc.

You can also get the key pairs on the curve, but if you need to signiture message, please use the signature util package, like ecdsa.

This package is pure dart and no 3rd dependency.

Usage

A simple usage example:

import 'package:elliptic/elliptic.dart';
import 'package:elliptic/ecdh.dart';
// if working with PEM
import 'package:pem/pem.dart';

void main() {
  // use elliptic curves 
  var ec = getP256();
  var priv = ec.generatePrivateKey();
  var pub = priv.publicKey;
  print('privateKey: 0x$priv');
  print('publicKey: 0x$pub');

  // use ecdh
  var privateAlice = ec.generatePrivateKey();
  var publicAlice = privateAlice.publicKey;
  var privateBob = ec.generatePrivateKey();
  var publicBob = privateBob.publicKey;
  var secretAlice = computeSecretHex(privateAlice, publicBob);
  var secretBob = computeSecretHex(privateBob, publicAlice);
  print('secretAlice: 0x$secretAlice');
  print('secretBob: 0x$secretBob');

  // working with PEM requires https://pub.dev/packages/pem
  // Parse PEM encoded private key.
  var rawPriv = PemCodec(PemLabel.privateKey).decode('''
    -----BEGIN PRIVATE KEY-----
    MIGEAgEAMBAGByqGSM49AgEGBSuBBAAKBG0wawIBAQQgVcB/UNPxalR9zDYAjQIf
    jojUDiQuGnSJrFEEzZPT/92hRANCAASc7UJtgnF/abqWM60T3XNJEzBv5ez9TdwK
    H0M6xpM2q+53wmsN/eYLdgtjgBd3DBmHtPilCkiFICXyaA8z9LkJ
    -----END PRIVATE KEY-----
  ''');
  // Parse PEM encoded public key.
  var privateFromPEM = PrivateKey.fromBytes(ec, rawPriv);
  print('privateAliceFromPEM: 0x$privateFromPEM');

  var keyData = PemCodec(PemLabel.publicKey).decode('''
    -----BEGIN PUBLIC KEY-----
    MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsjtGIk8SxD+OEiBpP2/T
    JUAF0upwuKGMk6wH8Rwov88VvzJrVm2NCticTk5FUg+UG5r8JArrV4tJPRHQyvqK
    wF4NiksuvOjv3HyIf4oaOhZjT8hDne1Bfv+cFqZJ61Gk0MjANh/T5q9vxER/7TdU
    NHKpoRV+NVlKN5bEU/NQ5FQjVXicfswxh6Y6fl2PIFqT2CfjD+FkBPU1iT9qyJYH
    A38IRvwNtcitFgCeZwdGPoxiPPh1WHY8VxpUVBv/2JsUtrB/rAIbGqZoxAIWvijJ
    Pe9o1TY3VlOzk9ASZ1AeatvOir+iDVJ5OpKmLnzc46QgGPUsjIyo6Sje9dxpGtoG
    QQIDAQAB
    -----END PUBLIC KEY-----
  ''');
  var hexPublickKey =
      keyData.map((e) => e.toRadixString(16).padLeft(2, '0')).join();
  var X = BigInt.parse(hexPublickKey.substring(0, 64), radix: 16);
  var Y = BigInt.parse(hexPublickKey.substring(64), radix: 16);
  var publicFromPEM = PublicKey(ec, X, Y);
  print('publicFromPEM: 0x$publicFromPEM');
}

Features and bugs

Please file feature requests and bugs at the issue tracker.

Libraries

ecdh

library ecdh, Elliptic-curve Diffie–Hellman (ECDH) is a key agreement protocol that allows two parties, each having an elliptic-curve public–private key pair, to establish a shared secret over an insecure channel.

elliptic

library elliptic provides a simple interface to elliptic curve cryptography.