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

21.2 POODLE

POODLE stands for Padding Oracle On Downgraded Legacy Encryption and was discovered in 2014 by Möller, Duong, and Kotowicz [122]. The name shows that the attack combines two other attacks described in Chapter 19, Attacks on Cryptography, and in Chapter 20, Attacks on the TLS Handshake Protocol, namely the padding oracle attack and the protocol downgrade attack. By exploiting some characteristics of SSL 3.0, Möller et al. could turn these two into one of the most severe attacks on TLS.

Basically, POODLE is an attack on SSL3.0. Although at the time the attack was published, the underlying weakness was already fixed in TLS 1.2 by introducing authenticated encryption into the TLS Record protocol, the attack remained relevant because of the downgrade dance explained in the previous chapter.

21.2.1 Attacker model

At the heart of the problem lies the MAC-then-encrypt construction deployed by SSL 3.0 described in Chapter 15, Authenticated Encryption...