Initial commit

.gitignore

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+bin/
+obj/
+.idea

YandexKeyExtractor.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "YandexKeyExtractor", "YandexKeyExtractor\YandexKeyExtractor.csproj", "{D059A2F0-8723-4479-89AE-59BC5F09B27D}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{D059A2F0-8723-4479-89AE-59BC5F09B27D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D059A2F0-8723-4479-89AE-59BC5F09B27D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D059A2F0-8723-4479-89AE-59BC5F09B27D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D059A2F0-8723-4479-89AE-59BC5F09B27D}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

YandexKeyExtractor/Decryptor.cs

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+using System;
+using System.Text;
+using CryptSharp.Utility;
+using NaCl;
+
+namespace YandexKeyExtractor {
+	public static class Decryptor {
+		public static string? Decrypt(string encryptedText, string password) {
+			string base64Text = NormalizeBase64(encryptedText);
+
+			Span<byte> textBytes = Convert.FromBase64String(base64Text).AsSpan();
+
+			const byte saltLength = 16;
+			Span<byte> textData = textBytes[..^saltLength];
+			Span<byte> textSalt = textBytes[^saltLength..];
+
+			byte[]? generatedPassword = SCrypt.ComputeDerivedKey(Encoding.UTF8.GetBytes(password), textSalt.ToArray(), 32768, 20, 1, null, 32);
+
+			using XSalsa20Poly1305 secureBox = new(generatedPassword);
+
+			const byte nonceLength = 24;
+			Span<byte> nonce = textData[..nonceLength];
+			Span<byte> dataWithMac = textData[nonceLength..];
+
+			Span<byte> message = stackalloc byte[dataWithMac.Length];
+
+			const byte macLength = 16;
+			Span<byte> data = dataWithMac[macLength..];
+			Span<byte> mac = dataWithMac[..macLength];
+
+			return secureBox.TryDecrypt(message, data, mac, nonce) ? new string(Encoding.UTF8.GetString(message).TrimEnd('\0')) : null;
+		}
+
+		private static string NormalizeBase64(string encryptedText) {
+			return encryptedText.Replace('-', '+').Replace('_', '/') + (encryptedText.Length % 4) switch {
+				2 => "==",
+				3 => "=",
+				_ => ""
+			};
+		}
+	}
+}

YandexKeyExtractor/Models/BackupInfoResponse.cs

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+using System.Text.Json.Serialization;
+
+namespace YandexKeyExtractor.Models {
+	public class BackupInfoResponse : StatusResponse {
+		[JsonPropertyName("backup_info")]
+		public BackupInfo? Info { get; set; }
+
+		public class BackupInfo {
+			[JsonNumberHandling(JsonNumberHandling.AllowReadingFromString)]
+			[JsonPropertyName("updated")]
+			public uint Updated { get; set; }
+		}
+	}
+}

YandexKeyExtractor/Models/BackupResponse.cs

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+using System.Text.Json.Serialization;
+
+namespace YandexKeyExtractor.Models {
+	public class BackupResponse : BackupInfoResponse {
+		[JsonPropertyName("backup")]
+		public string? Backup { get; set; }
+	}
+}

YandexKeyExtractor/Models/CountryResponse.cs

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+using System.Text.Json.Serialization;
+
+namespace YandexKeyExtractor.Models {
+	public class CountryResponse : StatusResponse {
+		[JsonPropertyName("country")]
+		public string[]? Country { get; set; }
+	}
+}

YandexKeyExtractor/Models/PhoneNumberResponse.cs

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+using System.Text.Json.Serialization;
+
+namespace YandexKeyExtractor.Models {
+	public class PhoneNumberResponse : StatusResponse {
+		[JsonPropertyName("number")]
+		public PhoneNumberInfo? PhoneNumber { get; set; }
+
+		public class PhoneNumberInfo {
+			[JsonPropertyName("e164")]
+			public string? StandardizedNumber { get; set; }
+		}
+	}
+}

YandexKeyExtractor/Models/StatusResponse.cs

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+using System.Text.Json.Serialization;
+
+namespace YandexKeyExtractor.Models {
+	public class StatusResponse {
+		[JsonPropertyName("status")]
+		public string? Status { get; set; }
+
+		[JsonPropertyName("errors")]
+		public string[]? Errors { get; set; }
+
+		public bool IsSuccess => Status == "ok";
+	}
+}

YandexKeyExtractor/Models/TrackResponse.cs

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+using System.Text.Json.Serialization;
+
+namespace YandexKeyExtractor.Models {
+	public class TrackResponse : StatusResponse {
+		[JsonPropertyName("track_id")]
+		public string? TrackID { get; set; }
+	}
+}

YandexKeyExtractor/Program.cs

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+using System;
+using System.IO;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+namespace YandexKeyExtractor {
+	internal static class Program {
+		private static async Task Main() {
+			Console.WriteLine("Initializing...");
+			using WebHandler handler = WebHandler.Create();
+
+			string country = await handler.TryGetCountry().ConfigureAwait(false);
+
+			PromptInput(out string phoneNumber, nameof(phoneNumber));
+
+			phoneNumber = phoneNumber.TrimStart('+');
+			string phone = await handler.GetPhoneNumberInfo(phoneNumber, country).ConfigureAwait(false);
+
+			string? trackID = await handler.SendSMSCodeAndGetTrackID(phone, country).ConfigureAwait(false);
+			if (string.IsNullOrEmpty(trackID)) {
+				return;
+			}
+
+			PromptInput(out string smsCode, nameof(smsCode));
+
+			if (!await handler.CheckCode(smsCode, trackID).ConfigureAwait(false)) {
+				return;
+			}
+
+			if (!await handler.ValidateBackupInfo(phone, trackID, country).ConfigureAwait(false)) {
+				return;
+			}
+
+			string? backup = await handler.GetBackupData(phone, trackID).ConfigureAwait(false);
+			if (string.IsNullOrEmpty(backup)) {
+				return;
+			}
+
+			PromptInput(out string backupPassword, nameof(backupPassword));
+
+			Console.WriteLine("Decrypting...");
+			string? message = Decryptor.Decrypt(backup, backupPassword);
+			if (string.IsNullOrEmpty(message)) {
+				Console.WriteLine("Decryption failed!");
+
+				return;
+			}
+
+			Console.WriteLine("Successfully decrypted!");
+			await File.WriteAllTextAsync("result.txt", message).ConfigureAwait(false);
+			Console.WriteLine($"Written {message.Split('\n').Length} authenticators to result file");
+		}
+
+		private static void PromptInput(out string result, [CallerArgumentExpression("result")] string argumentName = "") {
+			Console.WriteLine($"Enter {argumentName}:");
+			string? input = Console.ReadLine();
+			while (string.IsNullOrEmpty(input)) {
+				Console.WriteLine($"{argumentName} is invalid, try again:");
+				input = Console.ReadLine();
+			}
+
+			result = input;
+		}
+	}
+}

YandexKeyExtractor/WebHandler.cs

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+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Runtime.CompilerServices;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+using Flurl.Http;
+using Flurl.Serialization.TextJson;
+using YandexKeyExtractor.Models;
+
+namespace YandexKeyExtractor {
+	public sealed class WebHandler : IDisposable {
+		private WebHandler(IFlurlClient client) => Client = client;
+		private IFlurlClient Client { get; }
+
+		public void Dispose() {
+			Client.Dispose();
+		}
+
+		public async Task<bool> CheckCode(string? smsCode, string? trackID) {
+			StatusResponse? checkCodeResponse = await Client.Request("/bundle/yakey_backup/check_code/")
+				.PostUrlEncodedAsync(
+					new {
+						code = smsCode,
+						track_id = trackID
+					}
+				)
+				.ReceiveJson<StatusResponse?>()
+				.ConfigureAwait(false);
+
+			return ValidateResponse(checkCodeResponse, nameof(checkCodeResponse));
+		}
+
+		public static WebHandler Create() {
+			JsonSerializerOptions jsonSettings = new() {
+				DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
+			};
+
+			IFlurlClient? client = new FlurlClient(
+				new HttpClient {
+					DefaultRequestHeaders = { UserAgent = { new ProductInfoHeaderValue("okhttp", "2.7.5") } },
+					BaseAddress = new Uri("https://registrator.mobile.yandex.net/1/")
+				}
+			).Configure(settings => settings.WithTextJsonSerializer(jsonSettings));
+
+			return new WebHandler(client);
+		}
+
+		public async Task<string?> GetBackupData(string phone, string? trackID) {
+			BackupResponse? backupResponse = await Client.Request("/bundle/yakey_backup/download")
+				.PostUrlEncodedAsync(
+					new {
+						number = phone,
+						track_id = trackID
+					}
+				)
+				.ReceiveJson<BackupResponse?>()
+				.ConfigureAwait(false);
+
+			if (!ValidateResponse(backupResponse, nameof(backupResponse))) {
+				return null;
+			}
+
+			if (string.IsNullOrEmpty(backupResponse.Backup)) {
+				Console.WriteLine("Fatal error - Couldn't find valid backup!");
+
+				return null;
+			}
+
+			return backupResponse.Backup;
+		}
+
+		public async Task<string> GetPhoneNumberInfo(string? phoneNumber, string country) {
+			PhoneNumberResponse? phoneNumberResponse = await Client.Request("/bundle/validate/phone_number/")
+				.PostUrlEncodedAsync(
+					new {
+						phone_number = phoneNumber,
+						country
+					}
+				).ReceiveJson<PhoneNumberResponse?>()
+				.ConfigureAwait(false);
+
+			ValidateResponse(phoneNumberResponse, nameof(phoneNumberResponse));
+
+			string phone = phoneNumberResponse?.PhoneNumber?.StandardizedNumber ?? '+' + phoneNumber;
+
+			return phone;
+		}
+
+		public async Task<string?> SendSMSCodeAndGetTrackID(string phone, string country) {
+			TrackResponse? trackResponse = await Client.Request("/bundle/yakey_backup/send_code/")
+				.PostUrlEncodedAsync(
+					new {
+						display_language = "en",
+						number = phone,
+						country
+					}
+				)
+				.ReceiveJson<TrackResponse?>()
+				.ConfigureAwait(false);
+
+			if (!ValidateResponse(trackResponse, nameof(trackResponse))) {
+				return null;
+			}
+
+			string? trackID = trackResponse.TrackID;
+			if (string.IsNullOrEmpty(trackID)) {
+				Console.WriteLine("Track ID is empty!");
+
+				return null;
+			}
+
+			return trackID;
+		}
+
+		public async Task<string> TryGetCountry() {
+			CountryResponse? countryResponse = await Client.Request("/suggest/country")
+				.GetAsync()
+				.ReceiveJson<CountryResponse?>()
+				.ConfigureAwait(false);
+
+			ValidateResponse(countryResponse, nameof(countryResponse));
+
+			string country = countryResponse?.Country?.FirstOrDefault() ?? "ru";
+
+			return country;
+		}
+
+		public async Task<bool> ValidateBackupInfo(string phone, string? trackID, string country) {
+			BackupInfoResponse? backupInfoResponse = await Client.Request("/bundle/yakey_backup/info/")
+				.PostUrlEncodedAsync(
+					new {
+						number = phone,
+						track_id = trackID,
+						country
+					}
+				)
+				.ReceiveJson<BackupInfoResponse?>()
+				.ConfigureAwait(false);
+
+			if (!ValidateResponse(backupInfoResponse, nameof(backupInfoResponse))) {
+				return false;
+			}
+
+			if (backupInfoResponse.Info?.Updated == null) {
+				Console.WriteLine("Fatal error - Couldn't find valid backup!");
+
+				return false;
+			}
+
+			return true;
+		}
+
+
+		private static bool ValidateResponse<T>([NotNullWhen(true)] T? response, [CallerArgumentExpression("response")] string responseName = "") where T : StatusResponse {
+			if (response == null) {
+				Console.WriteLine(responseName + " failed!");
+
+				return false;
+			}
+
+			if (!response.IsSuccess) {
+				Console.WriteLine(responseName + $" failed with error {response.Status}!");
+				if (response.Errors != null) {
+					Console.WriteLine("Errors: " + string.Join(',', response.Errors));
+				}
+
+				return false;
+			}
+
+			return true;
+		}
+	}
+}

YandexKeyExtractor/YandexKeyExtractor.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<OutputType>Exe</OutputType>
+		<LangVersion>preview</LangVersion>
+		<TargetFramework>net6.0</TargetFramework>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="ConfigureAwaitChecker.Analyzer" Version="5.0.0">
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
+		<PackageReference Include="CryptSharpStandard" Version="1.0.0" />
+		<PackageReference Include="Flurl.Http" Version="3.2.0" />
+		<PackageReference Include="Flurl.Serialization.TextJson" Version="3.0.0" />
+		<PackageReference Include="NaCl.Net" Version="0.1.13" />
+	</ItemGroup>
+
+</Project>