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TrustPilotChallenge/dotnet/WhiteRabbit/Program.cs

122 lines
4.4 KiB

namespace WhiteRabbit
{
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Security.Cryptography;
using System.Text;
/// <summary>
/// Main class
/// </summary>
public static class Program
{
/// <summary>
/// Main entry point
/// </summary>
public static void Main()
{
var stopwatch = new Stopwatch();
stopwatch.Start();
var sourcePhrase = ConfigurationManager.AppSettings["SourcePhrase"];
var maxWordsInPhrase = int.Parse(ConfigurationManager.AppSettings["MaxWordsInPhrase"]);
if (sourcePhrase.Where(ch => ch != ' ').Count() + maxWordsInPhrase > 28)
{
Console.WriteLine("Only anagrams of up to 27 characters (including whitespace) are allowed");
return;
}
if (maxWordsInPhrase > Constants.MaxNumberOfWords)
{
Console.WriteLine($"Only anagrams of up to {Constants.MaxNumberOfWords} words are allowed");
return;
}
if (!BitConverter.IsLittleEndian)
{
Console.WriteLine("Only little-endian systems are supported due to MD5Digest optimizations");
return;
}
if (IntPtr.Size != 8)
{
Console.WriteLine("Only 64-bit systems are supported due to MD5Digest optimizations");
}
var expectedHashesFirstComponentsArray = new uint[8];
{
int i = 0;
foreach (var expectedHash in ConfigurationManager.AppSettings["ExpectedHashes"].Split(','))
{
expectedHashesFirstComponentsArray[i] = HexadecimalStringToUnsignedIntArray(expectedHash)[0];
expectedHashesFirstComponentsArray[i + 1] = HexadecimalStringToUnsignedIntArray(expectedHash)[0];
i += 2;
}
}
var processor = new StringsProcessor(
Encoding.ASCII.GetBytes(sourcePhrase),
maxWordsInPhrase,
ReadInput());
Console.WriteLine($"Initialization complete; time from start: {stopwatch.Elapsed}");
#if DEBUG
var fastPhrasesCount = processor.GetPhrasesCount();
Console.WriteLine($"Number of phrases: {fastPhrasesCount}; time from start: {stopwatch.Elapsed}");
#endif
stopwatch.Restart();
processor.CheckPhrases(expectedHashesFirstComponentsArray, (phraseBytes, hashFirstComponent) =>
{
var phrase = Encoding.ASCII.GetString(phraseBytes);
var hash = ComputeFullMD5(phraseBytes);
Console.WriteLine($"Found phrase for {hash} ({hashFirstComponent:x8}): {phrase}; time from start is {stopwatch.Elapsed}");
});
Console.WriteLine($"Done; time from start: {stopwatch.Elapsed}");
}
// Code taken from http://stackoverflow.com/a/321404/831314
private static uint[] HexadecimalStringToUnsignedIntArray(string hex)
{
return Enumerable.Range(0, hex.Length)
.Where(x => x % 8 == 0)
.Select(x => ChangeEndianness(hex.Substring(x, 8)))
.Select(hexLe => Convert.ToUInt32(hexLe, 16))
.ToArray();
}
// We can afford to spend some time here; this code will only run for matched phrases (and for one in several billion non-matched)
private static string ComputeFullMD5(byte[] phraseBytes)
{
using (var hashAlgorithm = new MD5CryptoServiceProvider())
{
var resultBytes = hashAlgorithm.ComputeHash(phraseBytes);
return string.Concat(resultBytes.Select(b => b.ToString("x2")));
}
}
private static string ChangeEndianness(string hex)
{
return hex.Substring(6, 2) + hex.Substring(4, 2) + hex.Substring(2, 2) + hex.Substring(0, 2);
}
private static IEnumerable<byte[]> ReadInput()
{
string line;
while ((line = Console.ReadLine()) != null)
{
yield return Encoding.ASCII.GetBytes(line);
}
}
}
}