Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/crypto/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.
+
+part of crypto;
+
+/**
+ * Hash-based Message Authentication Code support.
+ *
+ * The [add] method is used to add data to the message. The [digest] and
+ * [close] methods are used to extract the message authentication code.
+ */
+// TODO(floitsch): make Hash implement Sink, EventSink or similar.
+class HMAC {
+  final List<int> _message;
+  Hash _hash;
+  List<int> _key;
+  bool _isClosed = false;
+
+  /**
+   * Create an [HMAC] object from a [Hash] and a key.
+   */
+  HMAC(Hash this._hash, List<int> this._key): _message = [];
+
+  /**
+   * Add a list of bytes to the message.
+   */
+  void add(List<int> data) {
+    if (_isClosed) throw new StateError("HMAC is closed");
+    _message.addAll(data);
+  }
+
+  /**
+   * Extract the message digest as a list of bytes without closing [this].
+   */
+  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++) {
+      padding[i] = 0x36 ^ _key[i];
+    }
+
+    // Inner hash computation.
+    _hash = _hash.newInstance();
+    _hash.add(padding);
+    _hash.add(_message);
+    var innerHash = _hash.close();
+
+    // Compute outer padding.
+    for (var i = 0; i < blockSize; i++) {
+      padding[i] = 0x5c ^ _key[i];
+    }
+
+    // Outer hash computation which is the result.
+    _hash = _hash.newInstance();
+    _hash.add(padding);
+    _hash.add(innerHash);
+    return _hash.close();
+  }
+
+  /**
+   * Perform the actual computation and extract the message digest
+   * as a list of bytes.
+   */
+  List<int> close() {
+    _isClosed = true;
+    return digest;
+  }
+
+  /**
+   * Verify that the HMAC computed for the data so far matches the
+   * given message digest.
+   *
+   * This method should be used instead of memcmp-style comparisons
+   * to avoid leaking information via timing.
+   *
+   * Throws an exception if the given digest does not have the same
+   * size as the digest computed by this HMAC instance.
+   */
+  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;
+    for (var i = 0; i < digest.length; i++) {
+      result |= digest[i] ^ computedDigest[i];
+    }
+    return result == 0;
+  }
+}