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

22.7 BERserk attack

In 2014, Intel’s advanced threat research team and the French security researcher Antoine Delignat-Lavaud discovered a critical vulnerability in the then-current version of Mozilla’s Network Security Services (NSS) cryptographic library [85]. The attack was assigned the CVE number CVE-2014-1569.

The researchers gave the vulnerability the name BERserk, which is a pun on the Basic Encoding Rules (BER) encoding format. BER is a set of rules specified in International Telecommunications Union’s ASN.1 standard for encoding data into binary form.

NSS versions vulnerable to BERserk do not ensure that the BER encoding of an ASN.1 length is correctly formed. This, in turn, allows Mallory to forge RSA signatures using the PKCS#1 v1.5 RSA Signature Forgery attack published earlier by Daniel Bleichenbacher.

According to the PKCS#1 v1.5 standard, a plaintext’s hash to be signed must be padded as follows:


00 01 FF FF .. FF FF 00 DigestInfo MessageDigest...