MSSPI - Micro Security Support Provider Interface

A cross-platform C library that provides a high-level interface for TLS/DTLS operations using Windows SChannel or compatible implementations.

Features

• OpenSSL-compatible API: Core functions are interchangeable with OpenSSL counterparts
• Cross-platform: Windows, Linux, macOS, iOS, and MinGW support
• TLS/DTLS support: TLS 1.0-1.3 and DTLS 1.2 for secure connections
• CAPIX support: Crypto API Proxy - deferred loading of cryptographic libraries without compile-time linking
• Smart card support: PIN caching and hardware token integration

Documentation

• MSSPI - Core TLS/DTLS functions
• MSSPI_CERT - Certificate parsing functions
• CHANGELOG - Version history and changes

Real-World Usage

MSSPI powers TLS/SSL implementations in various projects across different ecosystems:

Project	Language	Purpose	Repository
Chromium-Gost	C++	Browser cryptography with GOST support	deemru/Chromium-Gost
stunnel-msspi	C	Enhanced SSL tunneling	CryptoPro/stunnel-msspi
go-msspi	Go	Go crypto framework integration	deemru/go-msspi
Qt OpenSSL Backend	C++	Qt framework SSL backend	deemru/qtbase

Key Integration Patterns

• Browser Integration: Seamless TLS handshake switching between different crypto libraries
• Tunneling: Enhanced SSL/TLS proxying with Windows cryptography
• Language Bindings: Native TLS support for Go applications
• Framework Backends: Drop-in SSL backend for Qt applications

Building

Windows

Builds a DLL with certificate parsing support:

cd build_windows
make.bat

This creates msspi.dll with full functionality including certificate parsing.

Linux

Build static libraries:

cd build_linux
make

Available targets:

• make or make all - Build all static libraries
• make static - Build basic library (libmsspi.a)
• make static-capix - Build with CAPIX support (libmsspi-capix.a) for CryptoPro GOST cryptography
• make shared - Build shared library (libmsspi.so)
• make clean - Clean build artifacts

Build options:

• MSSPI_USE_MSSPI_CERT - Include certificate parsing functionality
• MSSPI_USE_CAPIX - Enable Crypto API Proxy (CAPIX) for deferred loading of cryptographic libraries

License

See LICENSE file for details.

Contributing

Contributions are welcome! Please read the documentation and ensure your changes maintain API compatibility.