hashing.dart

import 'package:pinenacl/api.dart';
import 'package:pinenacl/src/digests/digests.dart';
import 'package:pinenacl/tweetnacl.dart';

void main() {
  const hex = Base16Encoder.instance;

  print('\n### Hashing - Blake2b Example ###\n');

  final hasher = Hash.blake2b;

  /// # Hashing
  print('Hash example\nH(\'\'): ${hex.encode(hasher(''))}');

  /// # Message authentication
  /// To authenticate a message, using a secret key, the blake2b function must be called as in the following example.
  print('\nMessage authentication');

  /// Message authentication example
  /// It can ganarate a MAC to be sure that the message is not forged.

  final msg = '256 BytesMessage' * 16;

  // the simplest way to get a cryptographic quality authKey
  // is to generate it with a cryptographic quality
  // random number generator
  final authKey = PineNaClUtils.randombytes(64);
  final mac = hasher(msg, key: authKey);

  print('MAC(msg, authKey): ${hex.encode(mac)}.\n');

  /// # Key derivation example
  /// The blake2b algorithm can replace a key derivation function by following the lines of:
  print('Key derivation example');
  final masterKey = PineNaClUtils.randombytes(64);
  final derivationSalt = PineNaClUtils.randombytes(16);

  final personalisation = Uint8List.fromList('<DK usage>'.codeUnits);

  final subKey = hasher('',
      key: masterKey, salt: derivationSalt, personalisation: personalisation);
  print('KDF(\'\', masterKey, salt, personalisation): ${hex.encode(subKey)}');

  /// By repeating the key derivation procedure before encrypting our messages,
  /// and sending the derivationSalt along with the encrypted message, we can expect to never reuse a key,
  /// drastically reducing the risks which ensue from such a reuse.

  /// SHA-256 Example.
  print('\nSHA-256 Example.\n');
  var message =
      '01234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789';
  final out = Hash.sha256(Uint8List.fromList(message.codeUnits));
  print('Resulted: ${hex.encode(out)}');
  print(
      'Expected: 3935959adc03ef044edba6e0c69dc7322e34668c2ca74470e4d39f20362b977a');

  final macOut = Uint8List(64);
  final k = List<int>.generate(128, (i) => i).toUint8List();
  final text =
      Uint8List.fromList('Sample message for keylen=blocklen'.codeUnits);

  TweetNaClExt.crypto_auth_hmacsha256(macOut, text, k);
  print('MAC 256: ${hex.encode(macOut)}');

  TweetNaClExt.crypto_auth_hmacsha512(macOut, text, k);
  print('MAC 512: ${hex.encode(macOut)}');
}