Recent content on ~erin/blog
Soatok yesterday alleged a pair of vulnerabilities in the Matrix Vodzemac cryptography library. I’m going to focus on the first here, 
 The basic gist of the issue is this: 
 
 Normally in Elliptic Curve Diffie-Hellman, you multiply your private key by the other party’s public key. 
 If, instead of their public key, they send you the “identity” curve…
Who’s allowed to reply to your posts? 
 Truthfully, anyone who can see it (and nothing can prevent someone who wants to from seeing something you make public). If they have to, they can link, copy and paste or screenshot it, and fundamentally there’s no way of stopping them. 
 But that’s not really what we’re talking about when we talk about replies on social…
The Fediverse has a bit of a moderation problem. In fact, it’s had one for quite a while. 
 When I wrote the first draft of the Activity Pump spec back in 2014, it had an Authorization section which began like this: 
 
 Authorization 
 This is a stub, to be expanded. OAuth 2.0 is an open question. 
 ActivityPump uses authorization for two purposes; first, to authenticate…
History 
 For the past few decades, the block cipher has been the primary symmetric cryptographic primitive. Aside from the odd stream cipher (primarily RC-4), pretty much every common cryptographic primitive from before 2010 can be seen as built from a block cipher. 
 Quick note: How do we define a block cipher? A block cipher is a function with the form c = f(p, k) where c , p are an…