Add totp authenticator

.gitignore

@@ -13,6 +13,7 @@ TestResults
 *.user
 *.sln.docstates
 .vs
+.idea
 
 # Build results
 [Dd]ebug/
@@ -117,4 +118,4 @@ protobuf/
 cryptopp/
 
 # misc
-Thumbs.db
+Thumbs.db

DepotDownloader/DownloadConfig.cs

@@ -28,5 +28,6 @@ namespace DepotDownloader
         public uint? LoginID { get; set; }
 
         public bool UseQrCode { get; set; }
+        public string TotpKey { get; set; }
     }
 }

DepotDownloader/Program.cs

@@ -46,6 +46,7 @@ namespace DepotDownloader
 
             var username = GetParameter<string>(args, "-username") ?? GetParameter<string>(args, "-user");
             var password = GetParameter<string>(args, "-password") ?? GetParameter<string>(args, "-pass");
+            ContentDownloader.Config.TotpKey = GetParameter<string>(args, "-totp-key");
             ContentDownloader.Config.RememberPassword = HasParameter(args, "-remember-password");
             ContentDownloader.Config.UseQrCode = HasParameter(args, "-qr");
 
@@ -401,6 +402,7 @@ namespace DepotDownloader
             Console.WriteLine("\t-max-servers <#>\t\t- maximum number of content servers to use. (default: 20).");
             Console.WriteLine("\t-max-downloads <#>\t\t- maximum number of chunks to download concurrently. (default: 8).");
             Console.WriteLine("\t-loginid <#>\t\t- a unique 32-bit integer Steam LogonID in decimal, required if running multiple instances of DepotDownloader concurrently.");
+            Console.WriteLine("\t-totp-key <key>\t\t- the TOTP authenticator key for the steam account, to automatically generate 2FA codes.");
         }
     }
 }

DepotDownloader/Steam3Session.cs

@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
+using System.Security.Cryptography;
 using System.Threading;
 using System.Threading.Tasks;
 using QRCoder;
@@ -508,12 +509,12 @@ namespace DepotDownloader
                     {
                         try
                         {
-                            authSession = await steamClient.Authentication.BeginAuthSessionViaCredentialsAsync(new SteamKit2.Authentication.AuthSessionDetails
+                            authSession = await steamClient.Authentication.BeginAuthSessionViaCredentialsAsync(new AuthSessionDetails
                             {
                                 Username = logonDetails.Username,
                                 Password = logonDetails.Password,
                                 IsPersistentSession = ContentDownloader.Config.RememberPassword,
-                                Authenticator = new UserConsoleAuthenticator(),
+                                Authenticator = new TotpAuthenticator(ContentDownloader.Config.TotpKey, new UserConsoleAuthenticator())
                             });
                         }
                         catch (TaskCanceledException)

DepotDownloader/TotpAuthenticator.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Security.Cryptography;
+using System.Threading.Tasks;
+using SteamKit2.Authentication;
+
+namespace DepotDownloader;
+
+/// <summary>
+/// Implementation of <see cref="IAuthenticator"/> that uses a TOTP Authenticator key to generate TOTP verification codes.
+/// Falls back to the provided fallback authenticator.
+/// </summary>
+public class TotpAuthenticator : IAuthenticator
+{
+    private readonly string _totpKey;
+    private readonly IAuthenticator _fallbackAuthenticator;
+
+    public TotpAuthenticator(string totpKey, IAuthenticator fallbackAuthenticator)
+    {
+        _totpKey = totpKey;
+        _fallbackAuthenticator = fallbackAuthenticator;
+    }
+
+    /// <inheritdoc />
+    public Task<string> GetDeviceCodeAsync(bool previousCodeWasIncorrect)
+    {
+        if (previousCodeWasIncorrect)
+        {
+            return _fallbackAuthenticator.GetDeviceCodeAsync(true);
+        }
+
+        var deviceCode = GetDeviceCode(_totpKey);
+        return deviceCode != null ? Task.FromResult(deviceCode) : _fallbackAuthenticator.GetDeviceCodeAsync(false);
+    }
+
+    /// <inheritdoc />
+    public Task<string> GetEmailCodeAsync(string email, bool previousCodeWasIncorrect)
+    {
+        return _fallbackAuthenticator.GetEmailCodeAsync(email, previousCodeWasIncorrect);
+    }
+
+    /// <inheritdoc />
+    public Task<bool> AcceptDeviceConfirmationAsync()
+    {
+        return _fallbackAuthenticator.AcceptDeviceConfirmationAsync();
+    }
+
+    // https://github.com/bitwarden/mobile/blob/7a65bf7fd7b44424073201c2c574d45b64b9ec9d/src/Core/Services/TotpService.cs
+    private static string GetDeviceCode(string key)
+    {
+        const int Digits = 5;
+        const int TotpDefaultTimer = 30;
+        const string SteamChars = "23456789BCDFGHJKMNPQRTVWXY";
+
+        if (string.IsNullOrWhiteSpace(key))
+        {
+            return null;
+        }
+
+        var keyBytes = Util.DecodeBase32String(key);
+        if (keyBytes == null || keyBytes.Length == 0)
+        {
+            return null;
+        }
+        var time = DateTimeOffset.Now.ToUnixTimeSeconds() / TotpDefaultTimer;
+        var timeBytes = BitConverter.GetBytes(time);
+        if (BitConverter.IsLittleEndian)
+        {
+            Array.Reverse(timeBytes, 0, timeBytes.Length);
+        }
+
+        var hash = new HMACSHA1(keyBytes).ComputeHash(timeBytes);
+
+        if (hash.Length == 0)
+        {
+            return null;
+        }
+
+        var offset = hash[^1] & 0xf;
+        var binary = ((hash[offset] & 0x7f) << 24) | ((hash[offset + 1] & 0xff) << 16) |
+                     ((hash[offset + 2] & 0xff) << 8) | (hash[offset + 3] & 0xff);
+
+        var otp = string.Empty;
+        var fullCode = binary & 0x7fffffff;
+        for (var i = 0; i < Digits; i++)
+        {
+            otp += SteamChars[fullCode % SteamChars.Length];
+            fullCode = (int)Math.Truncate(fullCode / (double)SteamChars.Length);
+        }
+        return otp;
+    }
+}

DepotDownloader/Util.cs

@@ -144,6 +144,69 @@ namespace DepotDownloader
             ).ToString();
         }
 
+        public static byte[] DecodeBase32String(string input)
+        {
+            const string Base32Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
+
+            if (input == null)
+            {
+                throw new ArgumentNullException(nameof(input));
+            }
+
+            input = input.ToUpperInvariant();
+            var cleanedInput = string.Empty;
+            foreach (var c in input)
+            {
+                if (Base32Chars.IndexOf(c) < 0)
+                {
+                    continue;
+                }
+
+                cleanedInput += c;
+            }
+
+            input = cleanedInput;
+            if (input.Length == 0)
+            {
+                return Array.Empty<byte>();
+            }
+
+            var output = new byte[input.Length * 5 / 8];
+            var bitIndex = 0;
+            var inputIndex = 0;
+            var outputBits = 0;
+            var outputIndex = 0;
+
+            while (outputIndex < output.Length)
+            {
+                var byteIndex = Base32Chars.IndexOf(input[inputIndex]);
+                if (byteIndex < 0)
+                {
+                    throw new FormatException();
+                }
+
+                var bits = Math.Min(5 - bitIndex, 8 - outputBits);
+                output[outputIndex] <<= bits;
+                output[outputIndex] |= (byte)(byteIndex >> (5 - (bitIndex + bits)));
+
+                bitIndex += bits;
+                if (bitIndex >= 5)
+                {
+                    inputIndex++;
+                    bitIndex = 0;
+                }
+
+                outputBits += bits;
+                if (outputBits >= 8)
+                {
+                    outputIndex++;
+                    outputBits = 0;
+                }
+            }
+
+            return output;
+        }
+
         public static async Task InvokeAsync(IEnumerable<Func<Task>> taskFactories, int maxDegreeOfParallelism)
         {
             if (taskFactories == null) throw new ArgumentNullException(nameof(taskFactories));

README.md

@@ -27,32 +27,33 @@ For example: `dotnet DepotDownloader.dll -app 730 -ugc 770604181014286929`
 
 ## Parameters
 
-Parameter | Description
+| Parameter             | Description                                                                                                                          |
---------- | -----------
+|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------|
--app \<#>				| the AppID to download.
+| -app \<#>             | the AppID to download.                                                                                                               |
--depot \<#>				| the DepotID to download.
+| -depot \<#>           | the DepotID to download.                                                                                                             |
--manifest \<id>			| manifest id of content to download (requires -depot, default: current for branch).
+| -manifest \<id>       | manifest id of content to download (requires -depot, default: current for branch).                                                   |
--ugc \<#>				| the UGC ID to download.
+| -ugc \<#>             | the UGC ID to download.                                                                                                              |
--beta \<branchname>		| download from specified branch if available (default: Public).
+| -beta \<branchname>   | download from specified branch if available (default: Public).                                                                       |
--betapassword \<pass>	| branch password if applicable.
+| -betapassword \<pass> | branch password if applicable.                                                                                                       |
--all-platforms			| downloads all platform-specific depots when -app is used.
+| -all-platforms        | downloads all platform-specific depots when -app is used.                                                                            |
--os \<os>				| the operating system for which to download the game (windows, macos or linux, default: OS the program is currently running on)
+| -os \<os>             | the operating system for which to download the game (windows, macos or linux, default: OS the program is currently running on)       |
--osarch \<arch>			| the architecture for which to download the game (32 or 64, default: the host's architecture)
+| -osarch \<arch>       | the architecture for which to download the game (32 or 64, default: the host's architecture)                                         |
--all-languages			| download all language-specific depots when -app is used.
+| -all-languages        | download all language-specific depots when -app is used.                                                                             |
--language \<lang>		| the language for which to download the game (default: english)
+| -language \<lang>     | the language for which to download the game (default: english)                                                                       |
--lowviolence			| download low violence depots when -app is used.
+| -lowviolence          | download low violence depots when -app is used.                                                                                      |
--pubfile \<#>			| the PublishedFileId to download. (Will automatically resolve to UGC id)
+| -pubfile \<#>         | the PublishedFileId to download. (Will automatically resolve to UGC id)                                                              |
--username \<user>		| the username of the account to login to for restricted content.
+| -username \<user>     | the username of the account to login to for restricted content.                                                                      |
--password \<pass>		| the password of the account to login to for restricted content.
+| -password \<pass>     | the password of the account to login to for restricted content.                                                                      |
--remember-password		| if set, remember the password for subsequent logins of this user. (Use -username <username> -remember-password as login credentials)
+| -remember-password    | if set, remember the password for subsequent logins of this user. (Use -username <username> -remember-password as login credentials) |
--dir \<installdir>		| the directory in which to place downloaded files.
+| -dir \<installdir>    | the directory in which to place downloaded files.                                                                                    |
--filelist \<file.txt>	| a list of files to download (from the manifest). Prefix file path with `regex:` if you want to match with regex.
+| -filelist \<file.txt> | a list of files to download (from the manifest). Prefix file path with `regex:` if you want to match with regex.                     |
--validate				| Include checksum verification of files already downloaded
+| -validate             | Include checksum verification of files already downloaded                                                                            |
--manifest-only			| downloads a human readable manifest for any depots that would be downloaded.
+| -manifest-only        | downloads a human readable manifest for any depots that would be downloaded.                                                         |
--cellid \<#>			| the overridden CellID of the content server to download from.
+| -cellid \<#>          | the overridden CellID of the content server to download from.                                                                        |
--max-servers \<#>		| maximum number of content servers to use. (default: 20).
+| -max-servers \<#>     | maximum number of content servers to use. (default: 20).                                                                             |
--max-downloads \<#>		| maximum number of chunks to download concurrently. (default: 8).
+| -max-downloads \<#>   | maximum number of chunks to download concurrently. (default: 8).                                                                     |
--loginid \<#>			| a unique 32-bit integer Steam LogonID in decimal, required if running multiple instances of DepotDownloader concurrently.
+| -loginid \<#>         | a unique 32-bit integer Steam LogonID in decimal, required if running multiple instances of DepotDownloader concurrently.            |
+| -totp-key \<key>      | the TOTP authenticator key for the steam account, to automatically generate 2FA codes.                                               |
 
 
 ## Frequently Asked Questions