| // Copyright (c) 2015, 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:typed_data'; |
| |
| /// A message digest as computed by a `Hash` or `HMAC` function. |
| class Digest { |
| /// The message digest as an array of bytes. |
| final List<int> bytes; |
| |
| Digest(this.bytes); |
| |
| /// Returns whether this is equal to another digest. |
| /// |
| /// This should be used instead of manual comparisons to avoid leaking |
| /// information via timing. |
| @override |
| bool operator ==(Object other) { |
| if (other is Digest) { |
| final a = bytes; |
| final b = other.bytes; |
| final n = a.length; |
| if (n != b.length) { |
| return false; |
| } |
| var mismatch = 0; |
| for (var i = 0; i < n; i++) { |
| mismatch |= a[i] ^ b[i]; |
| } |
| return mismatch == 0; |
| } |
| return false; |
| } |
| |
| @override |
| int get hashCode => Object.hashAll(bytes); |
| |
| /// The message digest as a string of hexadecimal digits. |
| @override |
| String toString() => _hexEncode(bytes); |
| } |
| |
| String _hexEncode(List<int> bytes) { |
| const hexDigits = '0123456789abcdef'; |
| var charCodes = Uint8List(bytes.length * 2); |
| for (var i = 0, j = 0; i < bytes.length; i++) { |
| var byte = bytes[i]; |
| charCodes[j++] = hexDigits.codeUnitAt((byte >> 4) & 0xF); |
| charCodes[j++] = hexDigits.codeUnitAt(byte & 0xF); |
| } |
| return String.fromCharCodes(charCodes); |
| } |