6.7 Major differences between TLS versions 1.3 and 1.2

While the focus of this book is to gain an in-depth understanding of the cryptography used in TLS 1.3, it is instructive to look at the changes TLS designers made between version 1.2 and version 1.3.

Insecure or unused cryptographic algorithms such as RSA, RC4, and SHA-1 and insecure modes of operation such as the Cipher Block Chaining (CBC) mode were either removed completely or, as in the case of SHA-1, only retained as legacy algorithms to ensure the verifiability of older certificates.

Further cryptographic improvements include the removal of compression, the Digital Signature Algorithm (DSA) (see Chapter 9, Digital Signatures), and client-generated ephemeral Diffie-Hellman groups.

A famous phrase in cryptography is that attacks only get better over time. Consequently, cryptographic algorithms and primitives do become insecure eventually and need to be exchanged. As a result, there are only five remaining cipher suites in...