steamguard-cli/Manifest.cs

using Newtonsoft.Json;
using SteamAuth;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;

namespace SteamGuard
{
	public class Manifest
	{
		private const int PBKDF2_ITERATIONS = 50000; //Set to 50k to make program not unbearably slow. May increase in future.
		private const int SALT_LENGTH = 8;
		private const int KEY_SIZE_BYTES = 32;
		private const int IV_LENGTH = 16;

		[JsonProperty("encrypted")]
		public bool Encrypted { get; set; }

		[JsonProperty("first_run")]
		public bool FirstRun { get; set; } = true;

		[JsonProperty("entries")]
		public List<ManifestEntry> Entries { get; set; }

		[JsonProperty("periodic_checking")]
		public bool PeriodicChecking { get; set; } = false;

		[JsonProperty("periodic_checking_interval")]
		public int PeriodicCheckingInterval { get; set; } = 5;

		[JsonProperty("periodic_checking_checkall")]
		public bool CheckAllAccounts { get; set; } = false;

		[JsonProperty("auto_confirm_market_transactions")]
		public bool AutoConfirmMarketTransactions { get; set; } = false;

		[JsonProperty("auto_confirm_trades")]
		public bool AutoConfirmTrades { get; set; } = false;

		private static Manifest _manifest { get; set; }

		public static Manifest GetManifest(bool forceLoad = false)
		{
			// Check if already staticly loaded
			if (_manifest != null && !forceLoad)
			{
				return _manifest;
			}

			// Find config dir and manifest file
			string maFile = Path.Combine(Program.SteamGuardPath, "manifest.json");

			// If there's no config dir, create it
			if (!Directory.Exists(Program.SteamGuardPath))
			{
				_manifest = _generateNewManifest();
				return _manifest;
			}

			// If there's no manifest, create it
			if (!File.Exists(maFile))
			{
				if (Program.Verbose) Console.WriteLine("warn: No manifest file found at {0}", maFile);
				bool? createNewManifest = Program.SteamGuardPath ==
										  Program.defaultSteamGuardPath.Replace("~", Environment.GetEnvironmentVariable("HOME")) ? true : (bool?) null;
				while (createNewManifest == null)
				{
					Console.Write($"Generate new manifest.json in {Program.SteamGuardPath}? [Y/n]");
					var answer = Console.ReadLine();
					if (answer != null)
						createNewManifest = !answer.StartsWith("n") && !answer.StartsWith("N");
				}
				if ((bool) createNewManifest)
				{
					_manifest = _generateNewManifest(true);
					return _manifest;
				}
				return null;
			}

			try
			{
				string manifestContents = File.ReadAllText(maFile);
				_manifest = JsonConvert.DeserializeObject<Manifest>(manifestContents);

				if (_manifest.Encrypted && _manifest.Entries.Count == 0)
				{
					_manifest.Encrypted = false;
					_manifest.Save();
				}

				_manifest.RecomputeExistingEntries();

				return _manifest;
			}
			catch (Exception ex)
			{
				Console.WriteLine("error: Could not open manifest file: {0}", ex.ToString());
				return null;
			}
		}

		private static Manifest _generateNewManifest(bool scanDir = false)
		{
			if (Program.Verbose) Console.WriteLine("Generating new manifest...");

			// No directory means no manifest file anyways.
			Manifest newManifest = new Manifest();
			newManifest.Encrypted = false;
			newManifest.PeriodicCheckingInterval = 5;
			newManifest.PeriodicChecking = false;
			newManifest.AutoConfirmMarketTransactions = false;
			newManifest.AutoConfirmTrades = false;
			newManifest.Entries = new List<ManifestEntry>();
			newManifest.FirstRun = true;

			// Take a pre-manifest version and generate a manifest for it.
			if (scanDir)
			{
				if (Directory.Exists(Program.SteamGuardPath))
				{
					DirectoryInfo dir = new DirectoryInfo(Program.SteamGuardPath);
					var files = dir.GetFiles();

					foreach (var file in files)
					{
						if (file.Extension != ".maFile") continue;

						string contents = File.ReadAllText(file.FullName);
						try
						{
							SteamGuardAccount account = JsonConvert.DeserializeObject<SteamGuardAccount>(contents);
							ManifestEntry newEntry = new ManifestEntry()
							{
								Filename = file.Name,
								SteamID = account.Session.SteamID
							};
							newManifest.Entries.Add(newEntry);
						}
						catch (Exception ex)
						{
							if (Program.Verbose) Console.WriteLine("warn: {0}", ex.Message);
						}
					}

					if (newManifest.Entries.Count > 0)
					{
						newManifest.Save();
						newManifest.PromptSetupPassKey(true);
					}
				}
			}

			if (newManifest.Save())
			{
				return newManifest;
			}

			return null;
		}

		public class IncorrectPassKeyException : Exception { }
		public class ManifestNotEncryptedException : Exception { }

		// TODO: move PromptForPassKey to Program.cs
		// TODO: make PromptForPassKey more secure
		public string PromptForPassKey()
		{
			if (!this.Encrypted)
			{
				throw new ManifestNotEncryptedException();
			}

			bool passKeyValid = false;
			string passKey = "";
			while (!passKeyValid)
			{
				Console.WriteLine("Please enter encryption password: ");
				passKey = Console.ReadLine();
				if (passKey == "")
					continue;
				passKeyValid = this.VerifyPasskey(passKey);
				if (!passKeyValid)
				{
					Console.WriteLine("Incorrect.");
				}
			}
			return passKey;
		}

		// TODO: move PromptSetupPassKey to Program.cs
		public string PromptSetupPassKey(bool inAccountSetupProcess = false)
		{
			if (inAccountSetupProcess)
			{
				Console.Write("Would you like to use encryption? [Y/n] ");
				string doEncryptAnswer = Console.ReadLine();
				if (doEncryptAnswer == "n" || doEncryptAnswer == "N")
				{
					Console.WriteLine("WARNING: You chose to not encrypt your files. Doing so imposes a security risk for yourself. If an attacker were to gain access to your computer, they could completely lock you out of your account and steal all your items.");
					Console.WriteLine("You may add encryption later using the --encrypt argument.");
					return null;
				}
			}

			string newPassKey = "";
			string confirmPassKey = "";
			do
			{
				Console.Write("Enter" + (inAccountSetupProcess ? " " : " new ") + "passkey: ");
				newPassKey = Console.ReadLine();
				Console.Write("Confirm" + (inAccountSetupProcess ? " " : " new ") + "passkey: ");
				confirmPassKey = Console.ReadLine();

				if (newPassKey != confirmPassKey)
				{
					Console.WriteLine("Passkeys do not match.");
				}
			} while (newPassKey != confirmPassKey || newPassKey == "");

			return newPassKey;
		}

		public SteamAuth.SteamGuardAccount[] GetAllAccounts(string passKey = null, int limit = -1)
		{
			if (passKey == null && this.Encrypted) return new SteamGuardAccount[0];

			List<SteamAuth.SteamGuardAccount> accounts = new List<SteamAuth.SteamGuardAccount>();
			foreach (var entry in this.Entries)
			{
				var account = GetAccount(entry, passKey);
				if (account == null) continue;
				accounts.Add(account);

				if (limit != -1 && limit >= accounts.Count)
					break;
			}

			return accounts.ToArray();
		}

		public SteamGuardAccount GetAccount(ManifestEntry entry, string passKey = null)
		{
			string fileText = "";
			Stream stream = null;
			RijndaelManaged aes256;

			if (this.Encrypted)
			{
				MemoryStream ms = new MemoryStream(Convert.FromBase64String(File.ReadAllText(Path.Combine(Program.SteamGuardPath, entry.Filename))));
				byte[] key = GetEncryptionKey(passKey, entry.Salt);

				aes256 = new RijndaelManaged
				{
					IV = Convert.FromBase64String(entry.IV),
					Key = key,
					Padding = PaddingMode.PKCS7,
					Mode = CipherMode.CBC
				};

				ICryptoTransform decryptor = aes256.CreateDecryptor(aes256.Key, aes256.IV);
				stream = new CryptoStream(ms, decryptor, CryptoStreamMode.Read);
			}
			else
			{
				FileStream fileStream = File.OpenRead(Path.Combine(Program.SteamGuardPath, entry.Filename));
				stream = fileStream;
			}

			if (Program.Verbose) Console.WriteLine("Decrypting...");
			using (StreamReader reader = new StreamReader(stream))
			{
				fileText = reader.ReadToEnd();
			}
			stream.Close();

			return JsonConvert.DeserializeObject<SteamAuth.SteamGuardAccount>(fileText);
		}

		public bool VerifyPasskey(string passkey)
		{
			if (!this.Encrypted || this.Entries.Count == 0) return true;

			var accounts = this.GetAllAccounts(passkey, 1);
			return accounts != null && accounts.Length == 1;
		}

		public bool RemoveAccount(SteamGuardAccount account, bool deleteMaFile = true)
		{
			ManifestEntry entry = (from e in this.Entries where e.SteamID == account.Session.SteamID select e).FirstOrDefault();
			if (entry == null) return true; // If something never existed, did you do what they asked?

			string filename = Path.Combine(Program.SteamGuardPath, entry.Filename);
			this.Entries.Remove(entry);

			if (this.Entries.Count == 0)
			{
				this.Encrypted = false;
			}

			if (this.Save() && deleteMaFile)
			{
				try
				{
					File.Delete(filename);
					return true;
				}
				catch (Exception)
				{
					return false;
				}
			}

			return false;
		}

		public bool SaveAccount(SteamGuardAccount account, bool encrypt, string passKey = null, string salt = null, string iV = null)
		{
			if (encrypt && (String.IsNullOrEmpty(passKey) || String.IsNullOrEmpty(salt) || String.IsNullOrEmpty(iV))) return false;

			string jsonAccount = JsonConvert.SerializeObject(account);

			string filename = account.Session.SteamID.ToString() + ".maFile";
			if (Program.Verbose) Console.WriteLine($"Saving account {account.AccountName} to {filename}...");

			ManifestEntry newEntry = new ManifestEntry()
			{
				SteamID = account.Session.SteamID,
				IV = iV,
				Salt = salt,
				Filename = filename
			};

			bool foundExistingEntry = false;
			for (int i = 0; i < this.Entries.Count; i++)
			{
				if (this.Entries[i].SteamID == account.Session.SteamID)
				{
					this.Entries[i] = newEntry;
					foundExistingEntry = true;
					break;
				}
			}

			if (!foundExistingEntry)
			{
				this.Entries.Add(newEntry);
			}

			bool wasEncrypted = this.Encrypted;
			this.Encrypted = encrypt;

			if (!this.Save())
			{
				this.Encrypted = wasEncrypted;
				return false;
			}

			try
			{
				Stream stream = null;
				MemoryStream ms = null;
				RijndaelManaged aes256;

				if (encrypt)
				{
					ms = new MemoryStream();
					byte[] key = GetEncryptionKey(passKey, newEntry.Salt);

					aes256 = new RijndaelManaged
					{
						IV = Convert.FromBase64String(newEntry.IV),
						Key = key,
						Padding = PaddingMode.PKCS7,
						Mode = CipherMode.CBC
					};

					ICryptoTransform encryptor = aes256.CreateEncryptor(aes256.Key, aes256.IV);
					stream = new CryptoStream(ms, encryptor, CryptoStreamMode.Write);
				}
				else
				{
					// An unencrypted maFile is shorter than the encrypted version,
					// so when an unencrypted maFile gets written this way, the file does not get wiped
					// leaving encrypted text after the final } bracket. Deleting and recreating the file fixes this.
					File.Delete(Path.Combine(Program.SteamGuardPath, newEntry.Filename));
					stream = File.OpenWrite(Path.Combine(Program.SteamGuardPath, newEntry.Filename)); // open or create
				}

				using (StreamWriter writer = new StreamWriter(stream))
				{
					writer.Write(jsonAccount);
				}

				if (encrypt)
				{
					File.WriteAllText(Path.Combine(Program.SteamGuardPath, newEntry.Filename), Convert.ToBase64String(ms.ToArray()));
				}

				stream.Close();
				return true;
			}
			catch (Exception ex)
			{
				if (Program.Verbose) Console.WriteLine("error: {0}", ex.ToString());
				return false;
			}
		}

		public bool Save()
		{
			string filename = Path.Combine(Program.SteamGuardPath, "manifest.json");
			if (!Directory.Exists(Program.SteamGuardPath))
			{
				try
				{
					if (Program.Verbose) Console.WriteLine("Creating {0}", Program.SteamGuardPath);
					Directory.CreateDirectory(Program.SteamGuardPath);
				}
				catch (Exception ex)
				{
					if (Program.Verbose) Console.WriteLine($"error: {ex.Message}");
					return false;
				}
			}

			try
			{
				string contents = JsonConvert.SerializeObject(this);
				File.WriteAllText(filename, contents);
				return true;
			}
			catch (Exception ex)
			{
				if (Program.Verbose) Console.WriteLine($"error: {ex.Message}");
				return false;
			}
		}

		private void RecomputeExistingEntries()
		{
			List<ManifestEntry> newEntries = new List<ManifestEntry>();

			foreach (var entry in this.Entries)
			{
				string filename = Path.Combine(Program.SteamGuardPath, entry.Filename);

				if (File.Exists(filename))
				{
					newEntries.Add(entry);
				}
			}

			this.Entries = newEntries;

			if (this.Entries.Count == 0)
			{
				this.Encrypted = false;
			}
		}

		public void MoveEntry(int from, int to)
		{
			if (from < 0 || to < 0 || from > Entries.Count || to > Entries.Count - 1) return;
			ManifestEntry sel = Entries[from];
			Entries.RemoveAt(from);
			Entries.Insert(to, sel);
			Save();
		}

		public class ManifestEntry
		{
			[JsonProperty("encryption_iv")]
			public string IV { get; set; }

			[JsonProperty("encryption_salt")]
			public string Salt { get; set; }

			[JsonProperty("filename")]
			public string Filename { get; set; }

			[JsonProperty("steamid")]
			public ulong SteamID { get; set; }
		}

		/*
		 Crypto Functions
		*/

		/// <summary>
		/// Returns an 8-byte cryptographically random salt in base64 encoding
		/// </summary>
		/// <returns></returns>
		public static string GetRandomSalt()
		{
			byte[] salt = new byte[SALT_LENGTH];
			using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
			{
				rng.GetBytes(salt);
			}
			return Convert.ToBase64String(salt);
		}

		/// <summary>
		/// Returns a 16-byte cryptographically random initialization vector (IV) in base64 encoding
		/// </summary>
		/// <returns></returns>
		public static string GetInitializationVector()
		{
			byte[] IV = new byte[IV_LENGTH];
			using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider())
			{
				rng.GetBytes(IV);
			}
			return Convert.ToBase64String(IV);
		}

		/// <summary>
		/// Generates an encryption key derived using a password, a random salt, and specified number of rounds of PBKDF2
		/// </summary>
		/// <param name="password"></param>
		/// <param name="salt"></param>
		/// <returns></returns>
		private static byte[] GetEncryptionKey(string password, string salt)
		{
			if (string.IsNullOrEmpty(password))
			{
				throw new ArgumentException("Password is empty");
			}
			if (string.IsNullOrEmpty(salt))
			{
				throw new ArgumentException("Salt is empty");
			}
			using (Rfc2898DeriveBytes pbkdf2 = new Rfc2898DeriveBytes(password, Convert.FromBase64String(salt), PBKDF2_ITERATIONS))
			{
				return pbkdf2.GetBytes(KEY_SIZE_BYTES);
			}
		}
	}
}