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fix: Fixes encryption support for pre-6.0.5 clients (#2365)

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### 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.
This commit is contained in:
Kamron Batman 2026-03-12 21:59:01 -07:00 • committed by GitHub
parent 76395b77ec
commit f150458578
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GPG key ID: B5690EEEBB952194
4 changed files with 71 additions and 23 deletions
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38
Projects/Server/Network/Encryption/LoginEncryption.cs
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@ -41,6 +41,7 @@ public sealed class LoginEncryption : IClientEncryption
/// <summary>
/// Attempts to initialize login encryption and validate the packet.
/// Returns true if the packet appears to be validly encrypted with this scheme.
/// When version is null (pre-6.0.5 clients that don't send 0xEF), tries all known legacy keys.
/// </summary>
public static bool TryDecrypt(
ClientVersion version,
@ -52,17 +53,41 @@ public sealed class LoginEncryption : IClientEncryption
encryption = null;
var keys = LoginKeys.GetKeys(version);
if (keys is { Key1: 0, Key2: 0 })
{
return false;
}
if (encryptedPacket.Length < LoginPacketSize)
{
return false;
}
if (version != null)
{
var keys = LoginKeys.GetKeys(version);
return keys is not { Key1: 0, Key2: 0 } && TryDecryptWithKeys(keys, seed, encryptedPacket, out encryption);
}
// No version available (pre-6.0.5 client) - try all known legacy keys
for (var i = 0; i < LoginKeys.LegacyKeys.Length; i++)
{
var legacyKeys = LoginKeys.LegacyKeys[i];
if (TryDecryptWithKeys(legacyKeys, seed, encryptedPacket, out encryption))
{
return true;
}
}
return false;
}
/// <summary>
/// Attempts decryption with a specific key pair and validates the result.
/// </summary>
private static bool TryDecryptWithKeys(
LoginKeys keys,
uint seed,
ReadOnlySpan<byte> encryptedPacket,
out LoginEncryption encryption)
{
const int LoginPacketSize = 62;
// Copy and decrypt
Span<byte> decrypted = stackalloc byte[LoginPacketSize];
encryptedPacket[..LoginPacketSize].CopyTo(decrypted);
@ -75,6 +100,7 @@ public sealed class LoginEncryption : IClientEncryption
// - Byte 60 must be 0x00 (null terminator for password)
if (decrypted[0] != 0x80 || decrypted[30] != 0x00 || decrypted[60] != 0x00)
{
encryption = null;
return false;
}