Implement HMAC support in lib/crypto.

lib/crypto/sha_utils.dart

Index: lib/crypto/sha_utils.dart
diff --git a/lib/crypto/sha_utils.dart b/lib/crypto/sha_utils.dart
index 42aebae7d082ec00d08a94709c0e66184d488a15..ebc19b96c1f508d4e07bd8916243eca30457407a 100644
--- a/lib/crypto/sha_utils.dart
+++ b/lib/crypto/sha_utils.dart
@@ -10,7 +10,7 @@ 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);
@@ -46,6 +46,11 @@ class _SHACryptoHashBase implements CryptoHash {
     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);
 
@@ -108,9 +113,9 @@ class _SHACryptoHashBase implements CryptoHash {
   }
 
   // Hasher state.
+  final int _chunkSizeInWords;
+  final int _digestSizeInWords;
   int _lengthInBytes = 0;
-  int _chunkSizeInWords;
-  int _digestSizeInWords;
   List<int> _pendingData;
   List<int> _currentChunk;
   List<int> _h;