Improving Application Security through TLS-Library Redesign

Research has revealed a number of pitfalls inherent in contemporary TLS libraries. Common mistakes when programming using their APIs include insufficient certificate verification and the use of weak cipher suites. These programmer errors leave applications susceptible to man-in-the-middle attacks. Furthermore, current TLS libraries encourage system designs which leave the confidentiality of secret authentication and session keys vulnerable to application flaws. This paper introduces libtlssep (pronounced lib·tē·el·sep), a new, open-source TLS library which provides a simpler API and improved security architecture. Applications that use libtlssep spawn a separate process whose role is to provide one or more TLS-protected communication channels; this child process assures proper certificate verification and isolates authentication and session keys in its separate memory space. We present a security, programmability, and performance analysis of libtlssep.