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TrustPilotChallenge/dotnet/WhiteRabbit/PhraseSet.cs

127 lines
5.2 KiB

namespace WhiteRabbit
{
using System;
using System.Diagnostics;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using WhiteRabbitUnmanagedBridge;
// Anagram representation optimized for MD5
internal struct PhraseSet
{
private uint[] Buffer;
public void Init()
{
this.Buffer = new uint[8 * Constants.PhrasesPerSet];
}
public unsafe void FillLength(int numberOfCharacters, int numberOfWords)
{
fixed (uint* bufferPointer = this.Buffer)
{
var length = (uint)(numberOfCharacters + numberOfWords - 1);
var lengthInBits = (uint)(length << 3);
for (var i = 0; i < Constants.PhrasesPerSet; i++)
{
bufferPointer[7 + i * 8] = lengthInBits;
((byte*)bufferPointer)[length + i * 32] = 128 ^ ' ';
}
}
}
public unsafe void ProcessPermutations(PhraseSet initialPhraseSet, Word[] allWords, int[] wordIndexes, ulong[] permutations, uint[] expectedHashesVector, Action<byte[], uint> action)
{
fixed (uint* bufferPointer = this.Buffer, initialBufferPointer = initialPhraseSet.Buffer)
{
fixed (ulong* permutationsPointer = permutations)
{
fixed (int* wordIndexesPointer = wordIndexes)
{
fixed (Word* allWordsPointer = allWords)
{
fixed (uint* expectedHashesPointer = expectedHashesVector)
{
for (var i = 0; i < permutations.Length; i += Constants.PhrasesPerSet)
{
MD5Unmanaged.FillPhraseSet(
(ulong*)initialBufferPointer,
(ulong*)bufferPointer,
(ulong*)allWordsPointer,
wordIndexesPointer,
permutationsPointer + i,
wordIndexes.Length);
MD5Unmanaged.ComputeMD5(bufferPointer, expectedHashesPointer);
if (bufferPointer[Constants.PhrasesPerSet / 2] != 0xFFFFFFFF)
{
for (var j = 0; j < Constants.PhrasesPerSet; j++)
{
// 16 matches are packed in 8 32-bit numbers: [0,1], [8,9], [2,3], [10,11], [4, 5], [12, 13], [6, 7], [14, 15]
var position = ((j / 2) % 4) * 2 + (j / 8);
var match = (bufferPointer[position] >> (4 * (j % 2))) & 0xF0F0F0F;
if (match != 0)
{
var bufferInfo = ((ulong)bufferPointer[Constants.PhrasesPerSet] << 32) | bufferPointer[j];
MD5Unmanaged.FillPhraseSet(
(ulong*)initialBufferPointer,
(ulong*)bufferPointer,
(ulong*)allWordsPointer,
wordIndexesPointer,
permutationsPointer + i,
wordIndexes.Length);
action(this.GetBytes(j), match);
break;
}
}
}
}
}
}
}
}
}
}
public unsafe byte[] GetBytes(int number)
{
Debug.Assert(number < Constants.PhrasesPerSet);
fixed (uint* bufferPointer = this.Buffer)
{
var phrasePointer = bufferPointer + 8 * number;
var length = 0;
for (var i = 27; i >= 0; i--)
{
if (((byte*)phrasePointer)[i] == 128)
{
length = i;
break;
}
}
var result = new byte[length];
for (var i = 0; i < length; i++)
{
result[i] = ((byte*)phrasePointer)[i];
}
return result;
}
}
public unsafe string DebugBytes(int number)
{
Debug.Assert(number < Constants.PhrasesPerSet);
fixed (uint* bufferPointer = this.Buffer)
{
var bytes = (byte*)bufferPointer;
return string.Concat(Enumerable.Range(32 * number, 32).Select(i => bytes[i].ToString("X2")));
}
}
}
}