Categories
Cryptography

Extending the AES-GCM Nonce Without Nightmare Fuel

When it comes to AES-GCM, I am not a fan. Most of my gripes fall into one of two categories: However, one of my gripes technically belongs in both categories: The small nonce size, which is caused by AES’s block size, limits the amount of data you can safely encrypt with a single symmetric key. […]

Categories
Cryptography

Understanding Extended-Nonce Constructions

How and why XSalsa20/XChaCha were designed, and why they’re secure.

Categories
Cryptography

Cryptographic Wear-Out for Symmetric Encryption

As we look upon the sunset of a remarkably tiresome year, I thought it would be appropriate to talk about cryptographic wear-out. What is cryptographic wear-out? It’s the threshold when you’ve used the same key to encrypt so much data that you should probably switch to a new key before you encrypt any more. Otherwise, […]

Categories
Badness Software Security

EduTech Spyware is Still Spyware: Proctorio Edition

Spyware written for educational institutions to flex their muscles of control over students and their families when learning from their home computer is still, categorically, spyware. Depending on your persuasion, the previous sentence sounds like either needless pedantry, or it reads like tautology. But we need to be clear on our terms. Educational spyware is […]

Categories
Cryptography

Comparison of Symmetric Encryption Methods

There seems to be a lot of interest among software developers in the various cryptographic building blocks (block ciphers, hash functions, etc.), and more specifically how they stack up against each other. Today, we’re going to look at how some symmetric encryption methods stack up against each other. If you’re just looking for a short […]

Categories
Cryptography

Why AES-GCM Sucks

If you’re reading this wondering if you should stop using AES-GCM in some standard protocol (TLS 1.3), the short answer is “No, you’re fine”. I specialize in secure implementations of cryptography, and my years of experience in this field have led me to dislike AES-GCM. This post is about why I dislike AES-GCM’s design, not […]