Okay so I've had my RSS reader open on this WhatsApp story for like three days now and I kept going back and forth on whether it's worth a post, but then I saw somebody share The Guardian's piece for the fourth time on Twitter this morning with a caption like "delete whatsapp now" and figured, yeah, this needs one.
Short version: on Friday The Guardian ran a story saying WhatsApp has a "backdoor" that could let the company (or Facebook, or presumably a government with the right subpoena) read your supposedly end-to-end encrypted messages. The claim comes from a UC Berkeley researcher named Tobias Boelter, and the mechanism itself is real, it's not made up. When a contact's encryption key changes (say they reinstall the app or switch phones), WhatsApp can, in certain cases, re-encrypt and resend messages that haven't been delivered yet, using the new key, without waiting for you to verify anything first. If you've got the safety-number-change notifications turned on you'll see a warning. That setting is off by default for basically everyone.
Where I land on this, after reading way more cryptography Twitter than is good for anyone on a Sunday: calling it a "backdoor" is doing a lot of work it shouldn't be doing. A backdoor implies someone built a secret door into the encryption on purpose so they could walk through it later. This is closer to a usability tradeoff that has a genuine privacy cost, and those are different things even if the practical worry (your message might get read by someone you didn't expect) rhymes.
Moxie Marlinspike, who literally wrote the protocol WhatsApp is using here through Open Whisper Systems, put out a pretty blunt rebuttal calling the framing irresponsible, and honestly I think he's right, even though it's a little funny watching the guy who built the thing defend it in public like this. His point is that any messaging system that doesn't force you to manually verify safety numbers before every single message is going to have some version of this same tradeoff, because otherwise messages just silently fail to send whenever someone gets a new phone, and normal people would lose their minds over that. Signal, his own app, handles the same situation a bit differently by not resending automatically. But that's a design choice, not evidence of a secret spy button hiding in the code.
That said, and this is the part that actually annoys me, I don't think WhatsApp is blameless here either. Burying the re-encryption notification toggle in settings instead of surfacing it, or at minimum explaining clearly what it does, is exactly the kind of decision that makes stories like this land as hard as they do. If a billion and a half people are trusting a little green lock icon that says "encrypted," the company probably owes them a plainer explanation of what that lock actually promises and where the edges are. My uncle is not going to go dig through Settings, Account, Security to turn on "Show Security Notifications." He doesn't know that setting exists and neither did I until Friday, and I write about this stuff for a living, sort of.
I went and turned the notifications on myself, which took about four taps. Now I get a little "Security code changed" message whenever a contact reinstalls. So far it's fired twice, both times because a friend switched phones, both times exactly as boring as you'd expect. I still think WhatsApp's encryption does what it says on the tin for basically everyone's actual threat model, which is nosy exes and workplace IT departments, not nation-states with warrants. If your threat model actually is a nation-state with a warrant, you probably shouldn't be taking security advice from my blog, you should be talking to an actual lawyer.
Also, completely unrelated, but CES coverage is still trickling into my inbox almost two weeks later and I am so done reading about smart fridges. Every single year there's a fridge with a screen bolted onto it, and every single year I do not care, and every single year somebody writes it up like it's the future. It is not the future. It is a fridge with a tablet glued to the door and a $3,500 price tag.
Not sure this story ends up mattering much past this week. But it's a decent reminder that "encrypted" is doing a lot of heavy lifting as a word, and most of us, myself included until Friday, have no idea what promises it's actually keeping on our behalf.