vlmcsd-rs

A Rust reimplementation of vlmcsd — a KMS (Key Management Service) emulator originally written in C by Wind4.

What is this?

vlmcsd is a fully Microsoft-compatible KMS server that provides product activation services for Volume License editions of Windows, Office, and other Microsoft products. This project is a clean-room port of the original C codebase to Rust, preserving full protocol compatibility while benefiting from Rust's memory safety and modern tooling.

Features

• Full KMS protocol support (V4, V5, V6)
• DCE/RPC framing with NDR32/NDR64 negotiation
• AES-128/160 encryption, SHA-256, HMAC-SHA256, AES-CMAC (all implemented in pure Rust, no external crypto dependencies)
• Embedded KMS database (vlmcsd.kmd) with product GUIDs and ePID generation
• Thread-per-connection server model
• Signal handling (SIGINT/SIGTERM) with graceful shutdown
• Daemon mode (Unix) with PID file support
• Client tool for sending activation requests
• C-compatible FFI library (shared + static) with auto-generated header

Binaries

Binary	Description
vlmcsd	KMS server daemon
vlmcs	KMS client / testing tool

Building

cargo build --release

The binaries will be at target/release/vlmcsd and target/release/vlmcs.

Usage

Server

# Start the KMS server (default: 0.0.0.0:1688)
vlmcsd

# Custom listen address and timeout
vlmcsd -L 192.168.1.100:1688 -t 60

# Run as daemon with PID file
vlmcsd -D -p /var/run/vlmcsd.pid

Server options:

Option	Description
-L, --listen <ADDR>	Listen address (default: 0.0.0.0:1688)
-t, --timeout <SECS>	Connection timeout in seconds (default: 30)
-D, --daemon	Run as daemon (Unix only)
-p, --pid-file <PATH>	Write PID to file
-V, --version	Print version
-h, --help	Print help

Client

# Activate against localhost
vlmcs

# Activate against a specific server
vlmcs 192.168.1.100:1688

# Force V4 protocol
vlmcs -4 192.168.1.100

# Select a specific product
vlmcs -l 3 192.168.1.100

# List available products
vlmcs -x

Client options:

Option	Description
-l <N>	Product index (use -x to list)
-4 / -5 / -6	Force protocol version
-n <COUNT>	Number of requests to send
-w <NAME>	Custom workstation name
-t <SECS>	Connection timeout (default: 30)
-v	Verbose output
-x	Show available products
-V, --version	Print version
-h, --help	Print help

C FFI Library

The project also builds libvlmcsd as both a shared library (.so/.dylib/.dll) and a static library (.a/.lib), with an auto-generated C header (vlmcsd.h).

#include "vlmcsd.h"

// Start a KMS server in a background thread
vlmcsd_start_server(1688);

// Process a raw KMS request
uint8_t *response;
size_t response_len;
vlmcsd_process_request(request, request_len, &response, &response_len);
vlmcsd_free(response, response_len);

// Query the product database
int count = vlmcsd_get_product_count();
char *name = vlmcsd_get_product_name(0);
vlmcsd_free_string(name);

Cross-compilation targets

Pre-built binaries are available via GitHub Actions for:

Target	Description
aarch64-apple-darwin	ARM64 macOS (Big Sur+)
x86_64-unknown-linux-gnu	64-bit Linux
aarch64-unknown-linux-gnu	ARM64 Linux
i686-unknown-linux-gnu	32-bit Linux
x86_64-pc-windows-msvc	64-bit Windows (MSVC)
i686-pc-windows-msvc	32-bit Windows (MSVC)
aarch64-pc-windows-msvc	ARM64 Windows (MSVC)
x86_64-pc-windows-gnu	64-bit Windows (MinGW)

Project structure

vlmcsd-rs/
  crates/
    vlmcsd-types/      # Core types: GUID, FileTime, Request, Response
    vlmcsd-crypto/     # AES, SHA-256, HMAC, CMAC (pure Rust)
    vlmcsd-kmsdata/    # KMD database parser with embedded data
    vlmcsd-protocol/   # KMS V4/V5/V6 protocol, ePID generation
    vlmcsd-rpc/        # DCE/RPC server (bind, request, NDR32/64)
    vlmcsd-network/    # TCP server with graceful shutdown
    vlmcsd-server/     # vlmcsd binary
    vlmcsd-client/     # vlmcs binary
    vlmcsd-ffi/        # C FFI library (cdylib + staticlib)

Credits

This project is a Rust port of vlmcsd by Wind4. All protocol logic, cryptographic routines, and the KMS database format are derived from the original C implementation.

License

MIT