FFLogsRehash.cs

using System;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Text;

namespace FFLogsRehash
{
    class Program
    {
        static void Main(string[] args)
        {
            var lines = File.ReadAllLines(args[0]);

            int lineCount = 0;
            for (int i = 0; i < lines.Length; i++)
            {
                lines[i] = lines[i].Substring(0, lines[i].LastIndexOf("|"));

                var lineType = lines[i].Substring(0, lines[i].IndexOf("|"));
                if (lineType == "01" || lineType == "253")
                    lineCount = 1;
                else
                    lineCount++;

                lines[i] = lines[i] + "|" + Meme(lines[i] + "|" + lineCount);
            }
            
            File.WriteAllLines(Path.GetFileNameWithoutExtension(args[0]) + "_rehashed.log", lines);
        }
        
        private static string Meme(string text)
        {
            MD5 md = MD5.Create();
            byte[] bytes = md.ComputeHash(Encoding.UTF8.GetBytes(text));
            return Mangle(bytes);
        }

        private static uint[] MakeConstant()
        {
            uint[] array = new uint[256];
            for (int i = 0; i < 256; i++)
            {
                string text = i.ToString("X2").ToLower();
                array[i] = (uint)(text[0] + ((uint)text[1] << 16));
            }
            return array;
        }

        private static string Mangle(byte[] bytes)
        {
            uint[] lookup = MakeConstant();
            char[] array = new char[bytes.Length * 2];
            for (int i = 0; i < bytes.Length; i++)
            {
                uint num = lookup[(int)bytes[i]];
                array[2 * i] = (char)num;
                array[2 * i + 1] = (char)(num >> 16);
            }
            return new string(array);
        }
    }
}