Crypto++ (cryptopp) vendor library — Completely removed from the project
Panama cipher (CFilterEncoder, CFilterDecoder) — Removed from NetStream
TEA encryption (tea.h, tea.cpp) — Removed from both client and server
DH2 key exchange (cipher.h, cipher.cpp) — Removed from EterBase
Camellia cipher — Removed all references
_IMPROVED_PACKET_ENCRYPTION_ — Entire system removed (XTEA key scheduling, sequence encryption, key agreement)
adwClientKey[4] — Removed from all packet structs (TPacketCGLogin2, TPacketCGLogin3, TPacketGDAuthLogin, TPacketGDLoginByKey, TPacketLoginOnSetup) and all associated code on both client and server
LSS_SECURITY_KEY — Dead code removed ("testtesttesttest" hardcoded key, GetSecurityKey() function)

New Encryption System (libsodium)

X25519 key exchange — SecureCipher class handles keypair generation and session key derivation via crypto_kx_client_session_keys / crypto_kx_server_session_keys
XChaCha20-Poly1305 AEAD — Used for authenticated encryption of handshake tokens (key exchange, session tokens)
XChaCha20 stream cipher — Used for in-place network buffer encryption via EncryptInPlace() / DecryptInPlace() (zero overhead, nonce-counter based replay prevention)
Challenge-response authentication — HMAC-based (crypto_auth) verification during key exchange to prove shared secret derivation
New handshake protocol — HEADER_GC_KEY_CHALLENGE / HEADER_CG_KEY_RESPONSE / HEADER_GC_KEY_COMPLETE packet flow for secure session establishment

Network Encryption Pipeline

Client send path — Data is encrypted at queue time in CNetworkStream::Send() (prevents double-encryption on partial TCP sends)
Client receive path — Data is decrypted immediately after recv() in __RecvInternalBuffer(), before being committed to the buffer
Server send path — Data is encrypted in DESC::Packet() via EncryptInPlace() after encoding to the output buffer
Server receive path — Newly received bytes are decrypted in DESC::ProcessInput() via DecryptInPlace() before buffer commit

Removed plaintext login path — HEADER_CG_LOGIN (direct password to game server) has been removed. All game server logins now require a login key obtained through the auth server (HEADER_CG_LOGIN2 / LoginByKey)
CSPRNG login keys — CreateLoginKey() now uses randombytes_uniform() (libsodium) instead of the non-cryptographic Xoshiro128PlusPlus PRNG
Single-use login keys — Keys are consumed (removed from the map) immediately after successful authentication
Shorter key expiry — Expired login keys are cleaned up after 15 seconds (down from 60 seconds). Orphaned keys (descriptor gone, never expired) are also cleaned up
Login rate limiting — Per-IP tracking of failed login attempts. After 5 failures within 60 seconds, the IP is blocked with a BLOCK status and disconnected. Counter resets after cooldown or successful login
Removed Brazil password bypass — The LC_IsBrazil() block that unconditionally disabled password verification has been removed

Pack File Encryption

libsodium-based pack encryption — PackLib now uses XChaCha20-Poly1305 for pack file encryption, replacing the legacy Camellia/XTEA system
Secure key derivation — Pack encryption keys are derived using crypto_pwhash (Argon2id)

Installation/Configuration

This is the third part of the entire project and it's about the client binary, the executable of the game.

Below you will find a comprehensive guide on how to configure all the necessary components from scratch.

This guide is made using a Windows environment as the main environment and cannot work in non-Windows operating systems!

This guide also uses the latest versions for all software demonstrated as of its creation date at February 4, 2026.

📋 Order of projects configuration

If one or more of the previous items is not yet configured please come back to this section after you complete their configuration steps.

✅ M2Dev Server Source

✅ M2Dev Server

▶️ M2Dev Client Source [YOU ARE HERE]

⏳ M2Dev Client [ALSO CONTAINS ADDITIONAL INFORMATION FOR POST-INSTALLATION STEPS]

🧱 Software Prerequisites

Please make sure that you have installed the following software in your machine before continuing:

  Visual Studio:  The software used to edit and compile the source code. Download

  Visual Studio Code (VS Code):  A lighter alternative to Visual Studio, harder to build the project in this software but it is recommended for code editing. Download

  Git:  Used to clone the repositories in your Windows machine. Download

  CMake:  Required for setting up and configuring the build of the source code. Download

  Notepad++ (optional but recommended):  Helps with quick, last minute edits. Download

👁️ Required Visual Studio packages

Make sure you have installed these packages with Visual Studio Installer in order to compile C++ codebases:

Packages

Note: Windows 11 SDK's can be replaced by Windows 10 SDK's, but it is recommended to install one of them.

⬇️ Obtaining the Client Source

To build the source for the first time, you first need to clone it. In your command prompt, cd into your desired location or create a new folder wherever you want and download the project using Git.

Here's how

Open up your terminal inside or cd into your desired folder and type this command:
git clone https://github.com/d1str4ught/m2dev-client-src.git
✅ You have successfully obtained the Client Source project!

🛠️ Building the Source Code

Building the project is extremely simple, if all Visual Studio components are being installed correctly.

Instructions

Open up your terminal inside, or cd in your project's root working directory and initialize the build with this command:
cmake -S . -B build
A new build folder has been created in your project's root directory. This folder contains all the build files and configurations, along with the sln file to open the project in Visual Studio.

Double click on that file to launch Visual Studio and load the project.

In the Solution Explorer, select all the projects minus the container folders, right click on one of the selected items, and click Properties

Next, make sure that the following settings are adjusted like this:

Windows SDK Version should be the latest of Windows 10. It is not recommended to select any Windows 11 versions yet if avalable.

Platform Toolset is the most important part for your build to succeed! Select the highest number you see. v145 is for Visual Studio 2026. If you are running Visual Studio 2022 you won't have that, you will have v143, select that one, same goes for older Visual Studio versions.

C++ Language Standard should be C++20 as it is the new standard defined in the CMakeList.txt files as well. Might as well set it like that for all dependencies.

C Language Standard should be C17 as it is the new standard defined in the CMakeList.txt files as well. Might as well set it like that for all dependencies.

Once done, click Apply and then OK to close this dialog.

After that, in the toolbar at the top of the window, select your desired output configuration:

Finally, click on the Build option at the top and select Build Solution, or simply press CTRL+SHIFT+B in your keyboard with all the projects selected.

Note: if this is NOT your first build after executing the cmake -S . -B build command for this workspace, it is recommended to click Clean Solution before Build Solution.

Where to find your compiled binaries:

Inside the build folder in your cloned repository, you should have a bin folder and inside that, you should have a Debug, Release, RelWithDebInfo or MinSizeRel folder, depending on your build configuration selection.

In that folder you should be seeing all your binaries:

If you did NOT install the Client project yet, you are done here.

If you HAVE the Client project installed, paste these 2 .exe files in these locations inside the Server project:

Metin2_<Debug|Release|RelWithDebInfo|MinSizeRel>.exe: inside root folder of the Client project

PackMaker.exe: inside assets\PackMaker.exe

✅ You have successfully built the Client Source!