Secure Channel Establishment in Disadvantaged Networks: TLS Optimization Using Intercepting Proxies

摘要

Transport Layer Security (TLS) is a secure communication protocol that is used in many secure electronic applications. In order to establish a TLS connection, a client and server engage in a handshake, which usually involves the transmission of digital certificates. In this thesis we develop a practical speedup of TLS handshakes over bandwidth-constrained, high-latency (i.e. disadvantaged) links by reducing the communication overhead associated with the transmission of digital certificates. This speedup is achieved by deploying two specialized TLS proxies across such links. Working in tandem, one proxy will replace certificate data in packets being sent across the disadvantaged link with a short reference, while the proxy on the other side of the link will restore the certificate data in the packet. The certificate data will be supplied by local or remote caches. Our solution preserves the end-to- end security of TLS and is designed to be transparent to third-party applications, and will thus facilitate rapid deployment by removing the need to modify existing installations of TLS clients and TLS servers. Testing shows that this technique can reduce the overall bandwidth used during a handshake by over 50%, and can reduce the time required to reestablish a secure channel by over 40% across Iridium links.