Securing the Web

Secure Sockets Layer, the ancestor of today's Transport Layer Security protocol, was developed by Netscape Communications for its web browser, with SSL 2.0 released in 1995 and quickly found to have serious design flaws, followed by a substantially redesigned SSL 3.0 in 1996. The protocol was handed to the Internet Engineering Task Force, which renamed it Transport Layer Security and published TLS 1.0 in 1999, followed by TLS 1.1 in 2006 and TLS 1.2 in 2008. SSL 3.0 itself was formally deprecated in 2015 after researchers disclosed the POODLE attack, which exploited weaknesses in how the old protocol handled block cipher padding to decrypt portions of supposedly protected traffic. TLS 1.3, finalized in 2018, represented the most significant redesign in the protocol's history, removing support for older, weaker cryptographic algorithms, streamlining the handshake to reduce the number of round trips needed before data can be sent, and, notably, requiring forward secrecy for every connection. At a conceptual level, a TLS handshake allows a client and server to agree on cryptographic algorithms, authenticate the server's identity through its certificate, and establish shared symmetric session keys, after which the bulk of the communication is protected using fast symmetric encryption rather than the slower public-key operations used only during setup.