| // Copyright 2014 The Flutter Authors. 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'; |
| |
| /// Data from a non-linear mathematical function that functions as |
| /// reproducible noise. |
| final Uint32List _noise = Uint32List.fromList(<int>[ |
| 0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a, |
| 0xa8304613, 0xfd469501, 0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, |
| 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821, 0xf61e2562, 0xc040b340, |
| 0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8, |
| 0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8, |
| 0x676f02d9, 0x8d2a4c8a, 0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c, |
| 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70, 0x289b7ec6, 0xeaa127fa, |
| 0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665, |
| 0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, |
| 0xffeff47d, 0x85845dd1, 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, |
| 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391 |
| ]); |
| |
| /// Per-round shift amounts. |
| const List<int> _shiftAmounts = <int>[ |
| 07, 12, 17, 22, 07, 12, 17, 22, 07, 12, 17, 22, 07, 12, 17, 22, 05, 09, 14, |
| 20, 05, 09, 14, 20, 05, 09, 14, 20, 05, 09, 14, 20, 04, 11, 16, 23, 04, 11, |
| 16, 23, 04, 11, 16, 23, 04, 11, 16, 23, 06, 10, 15, 21, 06, 10, 15, 21, 06, |
| 10, 15, 21, 06, 10, 15, 21 |
| ]; |
| |
| /// A bitmask that limits an integer to 32 bits. |
| const int _mask32 = 0xFFFFFFFF; |
| |
| /// An incremental hash computation of md5. |
| class Md5Hash { |
| Md5Hash() { |
| _digest[0] = 0x67452301; |
| _digest[1] = 0xefcdab89; |
| _digest[2] = 0x98badcfe; |
| _digest[3] = 0x10325476; |
| } |
| |
| // 64 bytes is 512 bits. |
| static const int _kChunkSize = 64; |
| |
| /// The current hash digest. |
| final Uint32List _digest = Uint32List(4); |
| final Uint8List _scratchSpace = Uint8List(_kChunkSize); |
| int _remainingLength = 0; |
| int _contentLength = 0; |
| |
| void addChunk(Uint8List data, [int? stop]) { |
| assert(_remainingLength == 0); |
| stop ??= data.length; |
| int i = 0; |
| for (; i <= stop - _kChunkSize; i += _kChunkSize) { |
| final Uint32List view = Uint32List.view(data.buffer, i, 16); |
| _writeChunk(view); |
| } |
| if (i != stop) { |
| // The data must be copied so that the provided buffer can be reused. |
| int j = 0; |
| for (; i < stop; i += 1) { |
| _scratchSpace[j] = data[i]; |
| j += 1; |
| } |
| _remainingLength = j; |
| } |
| _contentLength += stop; |
| } |
| |
| void _writeChunk(Uint32List chunk) { |
| // help dart remove bounds checks |
| // ignore: unnecessary_statements |
| chunk[15]; |
| // ignore: unnecessary_statements |
| _shiftAmounts[63]; |
| // ignore: unnecessary_statements |
| _noise[63]; |
| |
| int d = _digest[3]; |
| int c = _digest[2]; |
| int b = _digest[1]; |
| int a = _digest[0]; |
| int e = 0; |
| int f = 0; |
| int i = 0; |
| for (; i < 16; i += 1) { |
| e = (b & c) | ((~b & _mask32) & d); |
| f = i; |
| final int temp = d; |
| d = c; |
| c = b; |
| b = _add32( |
| b, |
| _rotl32(_add32(_add32(a, e), _add32(_noise[i], chunk[f])), |
| _shiftAmounts[i])); |
| a = temp; |
| } |
| for (; i < 32; i += 1) { |
| e = (d & b) | ((~d & _mask32) & c); |
| f = ((5 * i) + 1) % 16; |
| final int temp = d; |
| d = c; |
| c = b; |
| b = _add32( |
| b, |
| _rotl32(_add32(_add32(a, e), _add32(_noise[i], chunk[f])), |
| _shiftAmounts[i])); |
| a = temp; |
| } |
| for (; i < 48; i += 1) { |
| e = b ^ c ^ d; |
| f = ((3 * i) + 5) % 16; |
| final int temp = d; |
| d = c; |
| c = b; |
| b = _add32( |
| b, |
| _rotl32(_add32(_add32(a, e), _add32(_noise[i], chunk[f])), |
| _shiftAmounts[i])); |
| a = temp; |
| } |
| for (; i < 64; i+= 1) { |
| e = c ^ (b | (~d & _mask32)); |
| f = (7 * i) % 16; |
| final int temp = d; |
| d = c; |
| c = b; |
| b = _add32( |
| b, |
| _rotl32(_add32(_add32(a, e), _add32(_noise[i], chunk[f])), |
| _shiftAmounts[i])); |
| a = temp; |
| } |
| |
| _digest[0] += a; |
| _digest[1] += b; |
| _digest[2] += c; |
| _digest[3] += d; |
| } |
| |
| Uint32List finalize() { |
| // help dart remove bounds checks |
| // ignore: unnecessary_statements |
| _scratchSpace[63]; |
| _scratchSpace[_remainingLength] = 0x80; |
| _remainingLength += 1; |
| |
| final int zeroes = 56 - _remainingLength; |
| for (int i = _remainingLength; i < zeroes; i += 1) { |
| _scratchSpace[i] = 0; |
| } |
| final int bitLength = _contentLength * 8; |
| _scratchSpace.buffer.asByteData().setUint64(56, bitLength, Endian.little); |
| _writeChunk(Uint32List.view(_scratchSpace.buffer, 0, 16)); |
| return _digest; |
| } |
| |
| /// Adds [x] and [y] with 32-bit overflow semantics. |
| int _add32(int x, int y) => (x + y) & _mask32; |
| |
| /// Bitwise rotates [val] to the left by [shift], obeying 32-bit overflow |
| /// semantics. |
| int _rotl32(int val, int shift) { |
| final int modShift = shift & 31; |
| return ((val << modShift) & _mask32) | ((val & _mask32) >> (32 - modShift)); |
| } |
| } |