1
Is Telegram really an encrypted messaging app?
This blog is reserved for more serious things, and ordinarily I wouldn’t spend time on questions like the above. But much as I’d like to spend my time writing about exciting topics, som…
Matthew Green
Some random thoughts about crypto. Notes from a course I teach. Pictures of my dachshunds.
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2
Ok Google: please publish your DKIM secret keys
The Internet is a dangerous place in the best of times. Sometimes Internet engineers find ways to mitigate the worst of these threats, and sometimes they fail. Every now and then, however, a major …
3
Falling through the KRACKs
The big news in crypto today is the KRACK attack on WPA2 protected WiFi networks. Discovered by Mathy Vanhoef and Frank Piessens at KU Leuven, KRACK (Key Reinstallation Attack) leverages a vulnerab…
4
How does Apple privately find offline devices?
At Monday’s WWDC conference, Apple announced a cool new feature called “Find My”. Unlike Apple’s “Find my iPhone”, which uses cellular communication and the lost…
5
Why the Tor attack matters
Earlier today, Motherboard posted a court document filed in a prosecution against a Silk Road 2.0 user, indicating that the user had been de-anonymized on the Tor network thanks to research conduct…
6
The network is hostile
Yesterday the New York Times and ProPublica posted a lengthy investigation based on leaked NSA documents, outlining the extensive surveillance collaboration between AT&T and the U.S. government…
7
On the Juniper backdoor
You might have heard that a few days ago, Juniper Systems announced the discovery of “unauthorized code” in the ScreenOS software that underlies the NetScreen line of devices. As a resu…
8
Attack of the Week: Airdrop Tracing
It’s been a while since I wrote an “attack of the week” post, and the fault for this is entirely mine. I’ve been much too busy writing boring posts about Schnorr signatures!…
9
Kerberoasting
I learn about cryptographic vulnerabilities all the time, and they generally fill me with some combination of jealousy (“oh, why didn’t I think of that”) or else they impress me w…
10
Attack of the week: FREAK (or 'factoring the NSA for fun and profit')
This is the story of how a handful of cryptographers ‘hacked’ the NSA. It’s also a story of encryption backdoors, and why they never quite work out the way you want them to. But I…
11
Does Zoom use end-to-end encryption?
TL;DR: It’s complicated. Yesterday Zoom (the videoconferencing company, not the defunct telecom) put out a clarification post describing their encryption practices. This is a nice example of …
12
Attack of the Week: Group Messaging in WhatsApp and Signal
If you’ve read this blog before, you know that secure messaging is one of my favorite topics. However, recently I’ve been a bit disappointed. My sadness comes from the fact that lately …
13
Attack of the Week: Apple iMessage
Today’s Washington Post has a story entitled “Johns Hopkins researchers poke a hole in Apple’s encryption”, which describes the results of some research my students and I have bee…
14
Attack of the week: DUHK
Before we get started, fair warning: this is going to be a post about a fairly absurd (but non-trivial!) attack on cryptographic systems. But that’s ok, because it’s based on a fairly a…
15
A bit more on Twitter/X's new encrypted messaging
Update 6/10: Based on a short conversation with an engineering lead at X, some of the devices used at X are claimed to be using HSMs. See more further below. Matthew Garrett has a nice post about T…