Add source after decompiling and fixing

osu!decoder.sln

@@ -0,0 +1,22 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 15
+VisualStudioVersion = 15.0.26228.4
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "osu!decoder", "osu!decoder\osu!decoder.csproj", "{7CDE3892-D6ED-4784-AC5C-560649D75F9A}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{7CDE3892-D6ED-4784-AC5C-560649D75F9A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7CDE3892-D6ED-4784-AC5C-560649D75F9A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7CDE3892-D6ED-4784-AC5C-560649D75F9A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7CDE3892-D6ED-4784-AC5C-560649D75F9A}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+EndGlobal

osu!decoder/BinaryPatch.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using dnlib.DotNet;
+using dnlib.DotNet.Emit;
+
+namespace osu_decoder_dnlib
+{
+	// Token: 0x02000002 RID: 2
+	internal class BinaryPatch
+	{
+		// Token: 0x06000002 RID: 2 RVA: 0x00002058 File Offset: 0x00000258
+		public static void PatchSignatureCheck(ModuleDefMD module)
+		{
+			bool flag = false;
+			foreach (TypeDef typeDef in from a in module.Types
+			where a.Methods.Any((MethodDef b) => b.IsPinvokeImpl && b.ImplMap.Name == "WinVerifyTrust")
+			select a)
+			{
+				foreach (MethodDef methodDef in typeDef.Methods.Where((MethodDef a) => a.ReturnType.TypeName == "Boolean"))
+				{
+					Program.Verbose("Writing ret true to " + methodDef.FullName);
+					methodDef.Body.Instructions.Insert(0, new Instruction(OpCodes.Ldc_I4_1));
+					methodDef.Body.Instructions.Insert(1, new Instruction(OpCodes.Ret));
+					flag = true;
+				}
+			}
+			if (!flag)
+			{
+				Console.WriteLine("WARNING: did not write any changes.");
+			}
+		}
+
+		// Token: 0x06000003 RID: 3 RVA: 0x0000217C File Offset: 0x0000037C
+		public static void PatchExecutableName(ModuleDefMD module)
+		{
+			try
+			{
+				MethodDef methodDef = (MethodDef)module.EntryPoint.Body.Instructions[0].Operand;
+				Program.Verbose("Patching name check in " + methodDef.FullName);
+				IList<Instruction> instructions = methodDef.Body.Instructions;
+				Instruction item = instructions.Last((Instruction a) => a.OpCode == OpCodes.Brfalse_S);
+				int num = instructions.IndexOf(item);
+				for (int i = -4; i < 10; i++)
+				{
+					instructions[i + num].OpCode = OpCodes.Nop;
+				}
+			}
+			catch (Exception ex)
+			{
+				Console.WriteLine("Could not patch: " + ex.Message);
+			}
+		}
+
+		// Token: 0x06000004 RID: 4 RVA: 0x0000224C File Offset: 0x0000044C
+		public static MethodDef FindEazStringMethod(ModuleDefMD module)
+		{
+			MethodDef methodDef = (MethodDef)module.EntryPoint.Body.Instructions[0].Operand;
+			IList<Instruction> instructions = methodDef.Body.Instructions;
+			for (int i = 0; i < methodDef.Body.Instructions.Count; i++)
+			{
+				Instruction instruction = instructions[i];
+				MemberRef memberRef;
+				if (instruction.OpCode == OpCodes.Newobj && (memberRef = (instruction.Operand as MemberRef)) != null && memberRef.Class.Name == "Exception")
+				{
+					return (MethodDef)instructions[i - 1].Operand;
+				}
+			}
+			return null;
+		}
+	}
+}

osu!decoder/CliOptions.cs

@@ -0,0 +1,98 @@
+using System;
+using CommandLine;
+using CommandLine.Text;
+
+namespace osu_decoder_dnlib
+{
+	// Token: 0x02000004 RID: 4
+	internal class CliOptions
+	{
+		// Token: 0x17000001 RID: 1
+		// (get) Token: 0x0600000C RID: 12 RVA: 0x00002388 File Offset: 0x00000588
+		// (set) Token: 0x0600000D RID: 13 RVA: 0x00002390 File Offset: 0x00000590
+		[ValueOption(0)]
+		public string Input { get; set; }
+
+		// Token: 0x17000002 RID: 2
+		// (get) Token: 0x0600000E RID: 14 RVA: 0x0000239C File Offset: 0x0000059C
+		// (set) Token: 0x0600000F RID: 15 RVA: 0x000023A4 File Offset: 0x000005A4
+		[ValueOption(1)]
+		public string Input2 { get; set; }
+
+		// Token: 0x17000003 RID: 3
+		// (get) Token: 0x06000010 RID: 16 RVA: 0x000023B0 File Offset: 0x000005B0
+		// (set) Token: 0x06000011 RID: 17 RVA: 0x000023B8 File Offset: 0x000005B8
+		[Option('o', "output", HelpText = "Path of the output file")]
+		public string Output { get; set; }
+
+		// Token: 0x17000004 RID: 4
+		// (get) Token: 0x06000012 RID: 18 RVA: 0x000023C4 File Offset: 0x000005C4
+		// (set) Token: 0x06000013 RID: 19 RVA: 0x000023CC File Offset: 0x000005CC
+		[Option('v', "verbose", HelpText = "Prints more output.")]
+		public bool Verbose { get; set; }
+
+		// Token: 0x17000005 RID: 5
+		// (get) Token: 0x06000014 RID: 20 RVA: 0x000023D8 File Offset: 0x000005D8
+		// (set) Token: 0x06000015 RID: 21 RVA: 0x000023E0 File Offset: 0x000005E0
+		[Option('d', "debug", HelpText = "Prints a lot more output, you should pipe this to a file.")]
+		public bool Debug { get; set; }
+
+		// Token: 0x17000006 RID: 6
+		// (get) Token: 0x06000016 RID: 22 RVA: 0x000023EC File Offset: 0x000005EC
+		// (set) Token: 0x06000017 RID: 23 RVA: 0x000023F4 File Offset: 0x000005F4
+		[Option('s', "sourcemap", HelpText = "Writes a file containing an original:decoded source map.")]
+		public bool Sourcemap { get; set; }
+
+		// Token: 0x17000007 RID: 7
+		// (get) Token: 0x06000018 RID: 24 RVA: 0x00002400 File Offset: 0x00000600
+		// (set) Token: 0x06000019 RID: 25 RVA: 0x00002408 File Offset: 0x00000608
+		[Option('r', "dry-run", HelpText = "Do not write decoded executable to disk.")]
+		public bool DryRun { get; set; }
+
+		// Token: 0x17000008 RID: 8
+		// (get) Token: 0x0600001A RID: 26 RVA: 0x00002414 File Offset: 0x00000614
+		public string Password { get; } = "recorderinthesandybridge";
+
+		// Token: 0x17000009 RID: 9
+		// (get) Token: 0x0600001B RID: 27 RVA: 0x0000241C File Offset: 0x0000061C
+		// (set) Token: 0x0600001C RID: 28 RVA: 0x00002424 File Offset: 0x00000624
+		[Option("exp-eagerdecode", HelpText = "EXPERIMENTAL: decode from reference in method bodies", DefaultValue = false)]
+		public bool ExperimentEagerDecoding { get; set; }
+
+		// Token: 0x1700000A RID: 10
+		// (get) Token: 0x0600001D RID: 29 RVA: 0x00002430 File Offset: 0x00000630
+		// (set) Token: 0x0600001E RID: 30 RVA: 0x00002438 File Offset: 0x00000638
+		[Option("exp-secondpass", HelpText = "EXPERIMENTAL: do a second pass to check if everything is decoded", DefaultValue = false)]
+		public bool ExperimentSecondPass { get; set; }
+
+		// Token: 0x1700000B RID: 11
+		// (get) Token: 0x0600001F RID: 31 RVA: 0x00002444 File Offset: 0x00000644
+		// (set) Token: 0x06000020 RID: 32 RVA: 0x0000244C File Offset: 0x0000064C
+		[Option("exp-patch", HelpText = "Apply patch to remove signature and filename check", DefaultValue = false)]
+		public bool ExperimentPatch { get; set; }
+
+		// Token: 0x1700000C RID: 12
+		// (get) Token: 0x06000021 RID: 33 RVA: 0x00002458 File Offset: 0x00000658
+		// (set) Token: 0x06000022 RID: 34 RVA: 0x00002460 File Offset: 0x00000660
+		[Option("exp-full", HelpText = "Decode everything, resulting in unrunnable executable", DefaultValue = false)]
+		public bool ExperimentFullDecrypt { get; set; }
+
+		// Token: 0x06000023 RID: 35 RVA: 0x0000246C File Offset: 0x0000066C
+		[HelpOption]
+		public string GetHelp()
+		{
+			HelpText helpText = new HelpText();
+			helpText.Heading = new HeadingInfo("osu!decoder", "v1.2");
+			helpText.Copyright = new CopyrightInfo("HoLLy/JustM3", 2017);
+			helpText.AdditionalNewLineAfterOption = false;
+			helpText.AddDashesToOption = true;
+			helpText.MaximumDisplayWidth = Console.BufferWidth;
+			helpText.AddPreOptionsLine("\nExample usage:");
+			helpText.AddPreOptionsLine("\t- osu!decoder osu!.exe");
+			helpText.AddPreOptionsLine("\t- osu!decoder osu!.exe -v -p updated_password -o c:/newosu!.exe");
+			helpText.AddOptions(this);
+			helpText.AddPostOptionsLine("Please do not distribute. If you have this, it means I trust you :)");
+			return helpText;
+		}
+	}
+}

osu!decoder/CryptoHelper.cs

@@ -0,0 +1,137 @@
+using System;
+using System.IO;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace osu_decoder_dnlib
+{
+	// Token: 0x02000005 RID: 5
+	internal class CryptoHelper
+	{
+		// Token: 0x04000012 RID: 18
+		private readonly SymmetricAlgorithm _symmetricAlgorithm;
+
+		// Token: 0x06000025 RID: 37 RVA: 0x00002518 File Offset: 0x00000718
+		public CryptoHelper(string password)
+		{
+			Program.Verbose("Creating new decoder with password " + password);
+			this._symmetricAlgorithm = new RijndaelManaged
+			{
+				KeySize = 256,
+				BlockSize = 128,
+				IV = new Rfc2898DeriveBytes(password, new byte[]
+				{
+					28,
+					136,
+					27,
+					216,
+					83,
+					147,
+					140,
+					207,
+					60,
+					153,
+					41,
+					107,
+					117,
+					164,
+					37,
+					157,
+					94,
+					233,
+					51,
+					48,
+					146,
+					108,
+					127,
+					191,
+					30,
+					226,
+					250,
+					88,
+					109,
+					7,
+					132,
+					15
+				}).GetBytes(16),
+				Key = new Rfc2898DeriveBytes(password, new byte[]
+				{
+					167,
+					126,
+					112,
+					16,
+					4,
+					244,
+					15,
+					120,
+					135,
+					116,
+					123,
+					212,
+					157,
+					48,
+					5,
+					194,
+					12,
+					179,
+					153,
+					201,
+					204,
+					249,
+					248,
+					212,
+					86,
+					20,
+					215,
+					55,
+					105,
+					157,
+					111,
+					11
+				}).GetBytes(32)
+			};
+		}
+
+		// Token: 0x06000026 RID: 38 RVA: 0x000025A8 File Offset: 0x000007A8
+		internal string Decrypt(string input)
+		{
+			if (!input.StartsWith("#="))
+			{
+				throw new NotImplementedException("I don't support this encryption type");
+			}
+			string text = input.Substring(2);
+			if (text.StartsWith("q"))
+			{
+				text = text.Substring(1);
+				text = text.Replace('_', '+').Replace('$', '/');
+				string text2 = this.DecryptWithXor(Convert.FromBase64String(text));
+				Program.Debug(string.Format("Decrypted {0} to {1}", input, text2));
+				return text2;
+			}
+			throw new NotImplementedException("I don't support this encryption type (yet), poke me about it");
+		}
+
+		// Token: 0x06000027 RID: 39 RVA: 0x0000262C File Offset: 0x0000082C
+		private string DecryptWithXor(byte[] toDecrypt)
+		{
+			MemoryStream memoryStream = new MemoryStream();
+			using (ICryptoTransform cryptoTransform = this._symmetricAlgorithm.CreateDecryptor())
+			{
+				CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoTransform, CryptoStreamMode.Write);
+				cryptoStream.Write(toDecrypt, 0, toDecrypt.Length);
+				cryptoStream.FlushFinalBlock();
+				cryptoStream.Close();
+			}
+			toDecrypt = memoryStream.ToArray();
+			byte b = toDecrypt[toDecrypt.Length - 1];
+			Array.Resize<byte>(ref toDecrypt, toDecrypt.Length - 1);
+			for (int i = 0; i < toDecrypt.Length; i++)
+			{
+				byte[] array = toDecrypt;
+				int num = i;
+				array[num] ^= b;
+			}
+			return Encoding.UTF8.GetString(toDecrypt);
+		}
+	}
+}