The Transport Layer Security (TLS) Protocol Version 1.2
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T. Dierks, E. Rescorla · 2008-08
Abstract
This document specifies Version 1.2 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications security over the Internet, allowing client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery.
Why This RFC Matters
RFC 5246 defined TLS 1.2, which became the dominant version of TLS deployed on the internet for over a decade, securing HTTPS, SMTP submission, IMAP, and countless other protocols. Key advances over TLS 1.1 include support for authenticated encryption (AEAD) cipher suites such as AES-GCM, a more flexible pseudo-random function using SHA-256, and removal of the MD5/SHA-1 composite in the handshake hash. Although superseded by TLS 1.3 (RFC 8446), TLS 1.2 remains widely deployed and its cipher suite negotiation model influenced many subsequent protocol designs.