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

Loading, exporting, and encoding public and private keys

When you're working with asymmetric ciphers, one of the first problems you'll need to deal with is managing public and private keys, including loading and saving them to files or transmitting them to another person.

Both public and private keys contain long sequences of bytes. In the case of RSA, for example, private keys contain at least two main factors: a modulus and a secret exponent, each one long 2048, 3072, or 4096 bits (256, 384, or 512 bytes). Being binary data, they are not representable in a human-readable format, cannot be copied/pasted easily, and so on. To make handling keys more convenient, thus, we usually encode them.

Encoding keys as PEM

There are multiple formats for encoding private and public keys, but the de facto standard is DER-encoded ASN.1 stored in a PEM block, or simply "PEM format." Without getting into the details, which are not useful for our discussion, a PEM file contains...