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

14.4 Modes of operation

In the previous sections, we have discussed in detail how a block cipher encrypts a single block of plaintext data. But how should we proceed when faced with a large number of blocks? There are several possible answers to this question, each coming with its own advantages and disadvantages. The different approaches for encrypting a large number of blocks using a certain block cipher are called modes of operation.

As of the writing of this book, the following block cipher modes are approved by NIST:

  • The modes ECB, CBC, OFB, CFB, CTR, XTS-AES, FF1, and FF3, which can be used to achieve confidentiality

  • CMAC mode, which can be used to achieve authentication

  • The CCM, GCM, KW, KWP, and TKW modes, which combine confidentiality and message authentication

14.4.1 ECB mode

The Electronic Code Book (ECB) mode, shown in Figure 14.6, is the most straightforward mode of operation, where the ciphertext is obtained by directly applying the block cipher to the plaintext...