Implement HMAC support in lib/crypto.

lib/crypto/sha_utils.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.
 
 // Constants.
 final _MASK_8 = 0xff;
 final _MASK_32 = 0xffffffff;
 final _BITS_PER_BYTE = 8;
 final _BYTES_PER_WORD = 4;
 
 // Base class encapsulating common behavior for SHA cryptographic hash
 // functions.
-class _SHACryptoHashBase implements CryptoHash {
+class _SHACryptoHashBase {

[Ben Laurie (Google), 2012/04/27 13:26:33]

Why no longer implements CryptoHash?

[Mads Ager (google), 2012/04/30 07:56:57]

Because it doesn't. It does not have the newInstance method. I'll add it as an
abstract method and put back the implements.

   _SHACryptoHashBase(int this._chunkSizeInWords, int this._digestSizeInWords)
       : _pendingData = [] {
     _currentChunk = new List(_chunkSizeInWords);
     _h = new List(_digestSizeInWords);
   }
 
   // Update the hasher with more data.
   _SHACryptoHashBase update(List<int> data) {
     if (_digestCalled) {
       throw new CryptoHashException(
@@ skipping 15 matching lines @@
     _finalizeData();
     _iterate();
     assert(_pendingData.length == 0);
     var result = [];
     for (var i = 0; i < _h.length; i++) {
       result.addAll(_wordToBytes(_h[i]));
     }
     return result;
   }
 
+  // Returns the block size of the hash in bytes.
+  int get blockSize() {
+    return _chunkSizeInWords * _BYTES_PER_WORD;
+  }
+
   // One round of the hash computation.
   abstract _updateHash(List<int> m);
 
   // Helper methods.
   _add32(x, y) => (x + y) & _MASK_32;
   _roundUp(val, n) => (val + n - 1) & -n;
 
   // Converts a list of bytes to a chunk of 32-bit words.
   _bytesToChunk(List<int> data, int dataIndex) {
     assert((data.length - dataIndex) >= (_chunkSizeInWords * _BYTES_PER_WORD));
@@ skipping 42 matching lines @@
     var zeroPadding = finalizedLength - contentsLength;
     for (var i = 0; i < zeroPadding; i++) {
       _pendingData.add(0);
     }
     var lengthInBits = _lengthInBytes * _BITS_PER_BYTE;
     _pendingData.addAll(_wordToBytes(lengthInBits >> 32));
     _pendingData.addAll(_wordToBytes(lengthInBits & _MASK_32));
   }
 
   // Hasher state.
+  final int _chunkSizeInWords;
+  final int _digestSizeInWords;
   int _lengthInBytes = 0;
-  int _chunkSizeInWords;
-  int _digestSizeInWords;
   List<int> _pendingData;
   List<int> _currentChunk;
   List<int> _h;
   bool _digestCalled = false;
 }