GnuTLS Alternatives

OpenSSL is a framework which implements the secure socket layer. It ships with a program/library which gives you access to all those functions.

LibreSSL is a version of the TLS/crypto stack forked from OpenSSL in 2014, with goals of modernizing the codebase, improving security, and applying best practice development processes.

Themis is a cryptolibrary, providing high-quality security services for secure messaging and encrypted storage. Themis is aimed at modern development practices, with wrappers for Ruby, Python, PHP, Java / Android and iOS / OSX.

SecureBlackbox is a library (suite of components and classes) for software developers that allows them to provide secure data transfer and storage, digital signing and verification, encryption, and compression (please refer to /n software website to get the complete list of...

mbed TLS (formerly known as PolarSSL) makes it trivially easy for developers to include cryptographic and SSL/TLS capabilities in their (embedded) products, facilitating this functionality with a minimal coding footprint.

Network Security Services (NSS) comprises a set of libraries designed to support cross-platform development of security-enabled client and server applications with an option support for hardware SSL acceleration on the server side and hardware smart cards on the client side.

wolfSSL offers an embedded SSL implementation that is portable, progressive, and easy to use with products including the wolfSSL embedded SSL library and the wolfSSL Embedded Web Server.

The SSL/TLS and Certificate tutorial for Windows enables you to fast track your understanding of the SSL/TLS protocol, Certificate Management, and secure communication. The download includes many C source code examples, including a secure WebSocket tutorial.