Explore a comprehensive analysis of the Transport Layer Security (TLS) protocol's composite state machines in this IEEE conference talk. Delve into the challenges of designing robust state machines that correctly handle various protocol versions, extensions, authentication modes, and key exchange methods. Discover critical security vulnerabilities uncovered through systematic testing of popular open-source TLS implementations, including the FREAK flaw. Learn about the importance of formal verification for cryptographic protocol libraries and examine the first verified implementation of a composite TLS state machine in C. Gain insights into the complexities of TLS protocol design, the impact of state machine bugs, and the need for improved cryptographic protocol testing.