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

6.6 TLS version 1.3

In the years since its inception, TLS and its predecessor, SSL, have suffered a lot of attacks, both at the protocol level and the algorithm level (we will be discussing a few of them in Part IV, Bleeding Hearts and Biting Poodles). Step by step, these attacks have been mitigated in new TLS versions and extensions up to version 1.2. However, due to the need for backward compatibility and the resulting possibility for version rollback attacks, each new TLS version inherited the weaknesses of its predecessors. For example, the cumulative number of cipher suites in all TLS versions up to version 1.2 is 319, including a large number of outdated and insecure algorithms.

Figure 6.6: Overview of TLS session resumption (up to V1.2, adapted from [146])

Figure 6.6: Overview of TLS session resumption (up to V1.2, adapted from [146])

Therefore, in 2018, it was time for a larger clean-up: unsafe or unused options were removed in version 1.3, and version downgrade attempts are signaled to the client by the last eight bytes of Server˙...