f150458578
### Summary Fixes encryption detection for clients pre-6.0.5.0. To limit the amount of brute-force key checking we are only checking 4.0.11 to 6.0.4.
118 lines
4.2 KiB
C#
118 lines
4.2 KiB
C#
/*************************************************************************
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* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: LoginKeys.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.Collections.Generic;
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using System.Runtime.CompilerServices;
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namespace Server.Network;
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/// <summary>
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/// Represents encryption keys derived from a client version.
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/// Used for login packet encryption/decryption.
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/// </summary>
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public readonly struct LoginKeys
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{
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public static readonly LoginKeys Empty = new(0, 0);
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private static readonly Dictionary<ClientVersion, LoginKeys> _cache = [];
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private static LoginKeys[] _legacyKeys;
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public uint Key1 { get; }
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public uint Key2 { get; }
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private LoginKeys(uint key1, uint key2)
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{
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Key1 = key1;
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Key2 = key2;
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}
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/// <summary>
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/// Gets pre-computed login keys for all known client versions before 6.0.5
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/// that do not send the 0xEF packet (and thus have no version available at login time).
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/// </summary>
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public static ReadOnlySpan<LoginKeys> LegacyKeys => _legacyKeys ??= BuildLegacyKeys();
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/// <summary>
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/// Gets or computes encryption keys for the specified client version.
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/// Results are cached for performance.
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/// </summary>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static LoginKeys GetKeys(ClientVersion version)
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{
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if (version == null)
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{
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return Empty;
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}
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if (_cache.TryGetValue(version, out var keys))
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{
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return keys;
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}
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keys = ComputeKeys((uint)version.Major, (uint)version.Minor, (uint)version.Revision);
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_cache[version] = keys;
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return keys;
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}
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/// <summary>
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/// Computes encryption keys from version components using the UO key derivation algorithm.
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/// </summary>
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private static LoginKeys ComputeKeys(uint major, uint minor, uint revision)
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{
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// Key1 derivation
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uint key1 = (major << 23) | (minor << 14) | (revision << 4);
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key1 ^= (revision * revision) << 9;
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key1 ^= minor * minor;
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key1 ^= (minor * 11) << 24;
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key1 ^= (revision * 7) << 19;
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key1 ^= 0x2C13A5FD;
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// Key2 derivation
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uint key2 = (major << 22) | (revision << 13) | (minor << 3);
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key2 ^= (revision * revision * 3) << 10;
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key2 ^= minor * minor;
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key2 ^= (minor * 13) << 23;
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key2 ^= (revision * 7) << 18;
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key2 ^= 0xA31D527F;
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return new LoginKeys(key1, key2);
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}
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/// <summary>
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/// Builds the static array of pre-computed keys for pre-6.0.5 client versions.
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/// These versions don't send 0xEF, so login encryption must be detected by trying known keys.
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/// </summary>
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private static LoginKeys[] BuildLegacyKeys()
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{
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// All unique (Major, Minor, Revision) tuples from 4.0.11 through 6.0.4
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ReadOnlySpan<(uint Major, uint Minor, uint Revision)> versions =
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[
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(4, 0, 11),
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(5, 0, 0), (5, 0, 1), (5, 0, 2), (5, 0, 3), (5, 0, 4),
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(5, 0, 5), (5, 0, 6), (5, 0, 7), (5, 0, 8), (5, 0, 9),
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(6, 0, 0), (6, 0, 1), (6, 0, 2), (6, 0, 3), (6, 0, 4),
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];
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var keys = new LoginKeys[versions.Length];
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for (var i = 0; i < versions.Length; i++)
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{
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keys[i] = ComputeKeys(versions[i].Major, versions[i].Minor, versions[i].Revision);
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}
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return keys;
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}
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}
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