Change Hash subclasses to be Converters.

lib/src/hash_base.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.hash_base;
-
-import 'dart:typed_data';
-
-import 'package:typed_data/typed_data.dart';
-
-import 'hash.dart';
-import 'utils.dart';
-
-/// A base class for [Hash] implementations.
-///
-/// Subclasses should override [updateHash] and [digest].
-abstract class HashBase implements Hash {
-  /// Whether the hash function operates on big-endian words.
-  final Endianness _endian;
-
-  /// The words in the current chunk.
-  ///
-  /// This is an instance variable to avoid re-allocating, but its data isn't
-  /// used across invocations of [_iterate].
-  final Uint32List _currentChunk;
-
-  /// The length of the input data so far, in bytes.
-  int _lengthInBytes = 0;
-
-  /// Data that has yet to be processed by the hash function.
-  final _pendingData = new Uint8Buffer();
-
-  /// Whether [close] has been called.
-  bool _isClosed = false;
-
-  /// The words in the current digest.
-  ///
-  /// This should be updated each time [updateHash] is called.
-  Uint32List get digest;
-
-  int get blockSize => _currentChunk.lengthInBytes;
-
-  /// Creates a new hash.
-  ///
-  /// [chunkSizeInWords] represents the size of the input chunks processed by
-  /// the algorithm, in terms of 32-bit words.
-  HashBase(int chunkSizeInWords, {Endianness endian: Endianness.BIG_ENDIAN})
-      : _endian = endian,
-        _currentChunk = new Uint32List(chunkSizeInWords);
-
-  /// Runs a single iteration of the hash computation, updating [digest] with
-  /// the result.
-  ///
-  /// [m] is the current chunk, whose size is given by the `chunkSizeInWords`
-  /// parameter passed to the constructor.
-  void updateHash(Uint32List chunk);
-
-  void add(List<int> data) {
-    if (_isClosed) throw new StateError('Hash.add() called after close().');
-    _lengthInBytes += data.length;
-    _pendingData.addAll(data);
-    _iterate();
-  }
-
-  List<int> close() {
-    if (_isClosed) return _byteDigest();
-    _isClosed = true;
-
-    _finalizeData();
-    _iterate();
-    assert(_pendingData.isEmpty);
-    return _byteDigest();
-  }
-
-  Uint8List _byteDigest() {
-    if (_endian == Endianness.HOST_ENDIAN) return digest.buffer.asUint8List();
-
-    var byteDigest = new Uint8List(digest.lengthInBytes);
-    var byteData = byteDigest.buffer.asByteData();
-    for (var i = 0; i < digest.length; i++) {
-      byteData.setUint32(i * bytesPerWord, digest[i]);
-    }
-    return byteDigest;
-  }
-
-  /// Iterates through [_pendingData], updating the hash computation for each
-  /// chunk.
-  void _iterate() {
-    var pendingDataBytes = _pendingData.buffer.asByteData();
-    var pendingDataChunks = _pendingData.length ~/ _currentChunk.lengthInBytes;
-    for (var i = 0; i < pendingDataChunks; i++) {
-      // Copy words from the pending data buffer into the current chunk buffer.
-      for (var j = 0; j < _currentChunk.length; j++) {
-        _currentChunk[j] = pendingDataBytes.getUint32(
-            i * _currentChunk.lengthInBytes + j * bytesPerWord, _endian);
-      }
-
-      // Run the hash function on the current chunk.
-      updateHash(_currentChunk);
-    }
-
-    // Remove all pending data up to the last clean chunk break.
-    _pendingData.removeRange(
-        0, pendingDataChunks * _currentChunk.lengthInBytes);
-  }
-
-  /// Finalizes [_pendingData].
-  ///
-  /// This adds a 1 bit to the end of the message, and expands it with 0 bits to
-  /// pad it out.
-  void _finalizeData() {
-    // Pad out the data with 0x80, eight 0s, and as many more 0s as we need to
-    // land cleanly on a chunk boundary.
-    _pendingData.add(0x80);
-    var contentsLength = _lengthInBytes + 9;
-    var finalizedLength = _roundUp(contentsLength, _currentChunk.lengthInBytes);
-    for (var i = 0; i < finalizedLength - contentsLength; i++) {
-      _pendingData.add(0);
-    }
-
-    var lengthInBits = _lengthInBytes * bitsPerByte;
-    if (lengthInBits > maxUint64) {
-      throw new UnsupportedError(
-          "Hashing is unsupported for messages with more than 2^64 bits.");
-    }
-
-    // Add the full length of the input data as a 64-bit value at the end of the
-    // hash.
-    var offset = _pendingData.length;
-    _pendingData.addAll(new Uint8List(8));
-    _pendingData.buffer.asByteData().setUint64(offset, lengthInBits, _endian);
-  }
-
-  /// Rounds [val] up to the next multiple of [n], as long as [n] is a power of
-  /// two.
-  int _roundUp(int val, int n) => (val + n - 1) & -n;
-}