Improve the style of code in lib/.

lib/src/hmac.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library crypto.hmac;
 
+import 'dart:typed_data';
+
+import 'package:typed_data/typed_data.dart';
+
 import 'hash.dart';
 
 /// An implementation of [keyed-hash method authentication codes][rfc].
 ///
 /// [rfc]: https://tools.ietf.org/html/rfc2104
 ///
 /// HMAC allows messages to be cryptographically authenticated using any
 /// iterated cryptographic hash function.
 ///
 /// The message's data is added using [add]. Once it's been fully added, the
 /// [digest] and [close] methods can be used to extract the message
 /// authentication digest.
 ///
 /// If an expected authentication digest is available, the [verify] method may
 /// also be used to ensure that the message actually corresponds to that digest.
 // TODO(floitsch): make HMAC implement Sink, EventSink or similar.
 class HMAC {
   /// The bytes from the message so far.
-  final List<int> _message;
+  final _message = new Uint8Buffer();
 
   /// The hash function used to compute the authentication digest.
   Hash _hash;
 
   /// The secret key shared by the sender and the receiver.
-  List<int> _key;
+  final Uint8List _key;
 
-  /// Whether this is closed.
+  /// Whether [close] has been called.
   bool _isClosed = false;
 
   /// Create an [HMAC] object from a [Hash] and a binary key.
   ///
   /// The key should be a secret shared between the sender and receiver of the
   /// message.
-  HMAC(Hash this._hash, List<int> this._key) : _message = [];
+  HMAC(Hash hash, List<int> key)
+      : _hash = hash,
+        _key = new Uint8List(hash.blockSize) {
+    // Hash the key if it's longer than the block size of the hash.
+    if (key.length > _hash.blockSize) {
+      _hash = _hash.newInstance();
+      _hash.add(key);
+      key = _hash.close();
+    }
+
+    // If [key] is shorter than the block size, the rest of [_key] will be
+    // 0-padded.
+    _key.setRange(0, key.length, key);
+  }
 
   /// Adds a list of bytes to the message.
   ///
   /// If [this] has already been closed, throws a [StateError].
   void add(List<int> data) {
     if (_isClosed) throw new StateError("HMAC is closed");
     _message.addAll(data);
   }
 
   /// Returns the digest of the message so far, as a list of bytes.
   List<int> get digest {
-    var blockSize = _hash.blockSize;
-
-    // Hash the key if it is longer than the block size of the hash.
-    if (_key.length > blockSize) {
-      _hash = _hash.newInstance();
-      _hash.add(_key);
-      _key = _hash.close();
-    }
-
-    // Zero-pad the key until its size is equal to the block size of the hash.
-    if (_key.length < blockSize) {
-      var newKey = new List(blockSize);
-      newKey.setRange(0, _key.length, _key);
-      for (var i = _key.length; i < blockSize; i++) {
-        newKey[i] = 0;
-      }
-      _key = newKey;
-    }
-
     // Compute inner padding.
-    var padding = new List(blockSize);
-    for (var i = 0; i < blockSize; i++) {
+    var padding = new Uint8List(_key.length);
+    for (var i = 0; i < padding.length; i++) {
       padding[i] = 0x36 ^ _key[i];
     }
 
     // Inner hash computation.
     _hash = _hash.newInstance();
     _hash.add(padding);
     _hash.add(_message);
-    var innerHash = _hash.close();
+    var innerDigest = _hash.close();
 
     // Compute outer padding.
-    for (var i = 0; i < blockSize; i++) {
+    for (var i = 0; i < padding.length; i++) {
       padding[i] = 0x5c ^ _key[i];
     }
 
     // Outer hash computation which is the result.
     _hash = _hash.newInstance();
     _hash.add(padding);
-    _hash.add(innerHash);
+    _hash.add(innerDigest);
     return _hash.close();
   }
 
   /// Closes [this] and returns the digest of the message as a list of bytes.
   ///
   /// Once closed, [add] may no longer be called.
   List<int> close() {
     _isClosed = true;
     return digest;
   }
 
   /// Returns whether the digest computed for the data so far matches the given
   /// [digest].
   ///
   /// This method should be used instead of iterative comparisons to avoid
   /// leaking information via timing.
   ///
   /// Throws an [ArgumentError] if the given digest does not have the same size
   /// as the digest computed by [this].
   bool verify(List<int> digest) {
     var computedDigest = this.digest;
     if (digest.length != computedDigest.length) {
       throw new ArgumentError(
           'Invalid digest size: ${digest.length} in HMAC.verify. '
           'Expected: ${_hash.blockSize}.');
     }
-    int result = 0;
+
+    var result = 0;
     for (var i = 0; i < digest.length; i++) {
       result |= digest[i] ^ computedDigest[i];
     }
     return result == 0;
   }
 }