108 lines
3.1 KiB
Dart
108 lines
3.1 KiB
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.
|
||
|
|
|
||
|
|
import 'dart:convert';
|
||
|
|
import 'dart:typed_data';
|
||
|
|
|
||
|
|
import 'digest.dart';
|
||
|
|
import 'digest_sink.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.
|
||
|
|
class Hmac extends Converter<List<int>, Digest> {
|
||
|
|
/// The hash function used to compute the authentication digest.
|
||
|
|
final Hash _hash;
|
||
|
|
|
||
|
|
/// The secret key shared by the sender and the receiver.
|
||
|
|
final Uint8List _key;
|
||
|
|
|
||
|
|
/// 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 hash, List<int> key)
|
||
|
|
: _hash = hash,
|
||
|
|
_key = Uint8List(hash.blockSize) {
|
||
|
|
// Hash the key if it's longer than the block size of the hash.
|
||
|
|
if (key.length > _hash.blockSize) key = _hash.convert(key).bytes;
|
||
|
|
|
||
|
|
// If [key] is shorter than the block size, the rest of [_key] will be
|
||
|
|
// 0-padded.
|
||
|
|
_key.setRange(0, key.length, key);
|
||
|
|
}
|
||
|
|
|
||
|
|
@override
|
||
|
|
Digest convert(List<int> input) {
|
||
|
|
var innerSink = DigestSink();
|
||
|
|
var outerSink = startChunkedConversion(innerSink);
|
||
|
|
outerSink.add(input);
|
||
|
|
outerSink.close();
|
||
|
|
return innerSink.value;
|
||
|
|
}
|
||
|
|
|
||
|
|
@override
|
||
|
|
ByteConversionSink startChunkedConversion(Sink<Digest> sink) =>
|
||
|
|
_HmacSink(sink, _hash, _key);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// The concrete implementation of the HMAC algorithm.
|
||
|
|
class _HmacSink extends ByteConversionSink {
|
||
|
|
/// The sink for the outer hash computation.
|
||
|
|
final ByteConversionSink _outerSink;
|
||
|
|
|
||
|
|
/// The sink that [_innerSink]'s result will be added to when it's available.
|
||
|
|
final _innerResultSink = DigestSink();
|
||
|
|
|
||
|
|
/// The sink for the inner hash computation.
|
||
|
|
late final ByteConversionSink _innerSink;
|
||
|
|
|
||
|
|
/// Whether [close] has been called.
|
||
|
|
bool _isClosed = false;
|
||
|
|
|
||
|
|
_HmacSink(Sink<Digest> sink, Hash hash, List<int> key)
|
||
|
|
: _outerSink = hash.startChunkedConversion(sink) {
|
||
|
|
_innerSink = hash.startChunkedConversion(_innerResultSink);
|
||
|
|
|
||
|
|
// Compute outer padding.
|
||
|
|
var padding = Uint8List(key.length);
|
||
|
|
for (var i = 0; i < padding.length; i++) {
|
||
|
|
padding[i] = 0x5c ^ key[i];
|
||
|
|
}
|
||
|
|
_outerSink.add(padding);
|
||
|
|
|
||
|
|
// Compute inner padding.
|
||
|
|
for (var i = 0; i < padding.length; i++) {
|
||
|
|
padding[i] = 0x36 ^ key[i];
|
||
|
|
}
|
||
|
|
_innerSink.add(padding);
|
||
|
|
}
|
||
|
|
|
||
|
|
@override
|
||
|
|
void add(List<int> data) {
|
||
|
|
if (_isClosed) throw StateError('HMAC is closed');
|
||
|
|
_innerSink.add(data);
|
||
|
|
}
|
||
|
|
|
||
|
|
@override
|
||
|
|
void addSlice(List<int> data, int start, int end, bool isLast) {
|
||
|
|
if (_isClosed) throw StateError('HMAC is closed');
|
||
|
|
_innerSink.addSlice(data, start, end, isLast);
|
||
|
|
}
|
||
|
|
|
||
|
|
@override
|
||
|
|
void close() {
|
||
|
|
if (_isClosed) return;
|
||
|
|
_isClosed = true;
|
||
|
|
|
||
|
|
_innerSink.close();
|
||
|
|
_outerSink.add(_innerResultSink.value.bytes);
|
||
|
|
_outerSink.close();
|
||
|
|
}
|
||
|
|
}
|