Book Image

TLS Cryptography In-Depth

By : Dr. Paul Duplys, Dr. Roland Schmitz
Book Image

TLS Cryptography In-Depth

By: Dr. Paul Duplys, Dr. Roland Schmitz

Overview of this book

TLS is the most widely used cryptographic protocol today, enabling e-commerce, online banking, and secure online communication. Written by Dr. Paul Duplys, Security, Privacy & Safety Research Lead at Bosch, and Dr. Roland Schmitz, Internet Security Professor at Stuttgart Media University, this book will help you gain a deep understanding of how and why TLS works, how past attacks on TLS were possible, and how vulnerabilities that enabled them were addressed in the latest TLS version 1.3. By exploring the inner workings of TLS, you’ll be able to configure it and use it more securely. Starting with the basic concepts, you’ll be led step by step through the world of modern cryptography, guided by the TLS protocol. As you advance, you’ll be learning about the necessary mathematical concepts from scratch. Topics such as public-key cryptography based on elliptic curves will be explained with a view on real-world applications in TLS. With easy-to-understand concepts, you’ll find out how secret keys are generated and exchanged in TLS, and how they are used to creating a secure channel between a client and a server. By the end of this book, you’ll have the knowledge to configure TLS servers securely. Moreover, you’ll have gained a deep knowledge of the cryptographic primitives that make up TLS.
Table of Contents (30 chapters)
1
Part I Getting Started
8
Part II Shaking Hands
16
Part III Off the Record
22
Part IV Bleeding Hearts and Biting Poodles
27
Bibliography
28
Index

16

The Galois Counter Mode

In the previous chapter, we learned about authenticated encryption and authenticated encryption with additional data. We saw how authenticated encryption can be obtained from simpler cryptographic primitives using generic composition, and we introduced a dedicated counter mode with CBC-MAC (CCM) that provides AEAD.

In TLS 1.3, AEAD is used for protecting all TLS Record protocol payloads. In this chapter, we will study Galois/Counter Mode (GCM), an AEAD algorithm that every TLS 1.3 endpoint must implement. RFC 8446 [147], the specification of TLS 1.3, only references NIST’s Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC [57], where GCM is specified. But since GCM is used in the TLS Record protocol, the material we will discuss in this chapter is related to Chapter 5, Record Protocol, of RFC 8446.

Upon completion of the chapter, you will be familiar with GCM’s mathematical foundations, architecture...