Book Image

Essential Cryptography for JavaScript Developers

By : Alessandro Segala
Book Image

Essential Cryptography for JavaScript Developers

By: Alessandro Segala

Overview of this book

If you’re a software developer, this book will give you an introduction to cryptography, helping you understand how to make the most of it for your applications. The book contains extensive code samples in JavaScript, both for Node.js and for frontend apps running in a web browser, although the core concepts can be used by developers working with any programming language and framework. With a purely hands-on approach that is focused on sharing actionable knowledge, you’ll learn about the common categories of cryptographic operations that you can leverage in all apps you’re developing, including hashing, encryption with symmetric, asymmetric and hybrid ciphers, and digital signatures. You’ll learn when to use these operations and how to choose and implement the most popular algorithms to perform them, including SHA-2, Argon2, AES, ChaCha20-Poly1305, RSA, and Elliptic Curve Cryptography. Later, you’ll learn how to deal with password and key management. All code in this book is written in JavaScript and designed to run in Node.js or as part of frontend apps for web browsers. By the end of this book, you'll be able to build solutions that leverage cryptography to protect user privacy, offer better security against an expanding and more complex threat landscape, help meet data protection requirements, and unlock new opportunities.
Table of Contents (13 chapters)
Part 1 – Getting Started
Part 2 – Using Common Cryptographic Operations with Node.js
Part 3 – Cryptography in the Browser

How to "break" a hash

Let me start by offering an apology for perhaps misnaming this section. In Chapter 1, Cryptography for Developers, we explained that "breaking" a cryptographic algorithm requires finding ways to derive the plaintext – or, in the case of hashes, finding collisions – without performing brute-force attacks (more on collisions at the end of this chapter).

So far, as I'm writing this book, SHA-2 hashes have not been "broken." This means that no one has found vulnerabilities that make them significantly less secure, which happened to older (but still very popular) hashing functions such as MD5 and SHA-1, for which practical collision attacks have been demonstrated.

Yet, it's still not recommended to use SHA-2 on low-entropy inputs, such as passwords. The problem, which may come as a surprise to some, is that SHA-2 is too fast to compute.

Fast hashing functions and low-entropy inputs

When you store passwords...