On 1/25/21, Punk-BatSoup-Stasi 2.0 <punks@tfwno.gf> wrote:
On Mon, 25 Jan 2021 13:57:21 -0500 Karl <gmkarl@gmail.com> wrote:
4. perfect forward secrecy. addresses the issue with pgp where future advancements decrypt all your messages
As far as I understand it, what signal and other systems do is generate 'ephemeral' keys (per session or even per message).
Now, if all traffic is recorded (which of course it is), and the key exchange broken thanks to say 'quantum computers', then the 'ephemeral' keys can be re-created. So as far as I can tell your claim is wrong, and 'perfect forward secrecy' is a misleading marketing term.
But I might have got it wrong myself...
Well, I'm too foggy nowadays to understand the protocol, but I read it long ago. The term is mathematical rather than marketing. Obviously if you capture/recreate the private data when it is created you can decrypt everything, because you then are one of the phones.
5. metadata encryption. pgp does not do this
neither does signal. Or rather
https://en.wikipedia.org/wiki/Signal_Protocol#Metadata
"In October 2018, Signal Messenger announced that they had implemented a "sealed sender" feature into Signal, which reduces the amount of metadata that the Signal servers have access to by concealing the sender's identifier."
Not sure what that actually means. Also
"The Signal Protocol does not prevent a company from retaining information about when and with whom users communicate."
Of course the protocol does not prevent the server from KNOWING who talks to whom...
What's important to understand here is that these developers are cryptographers. When they say "metadata that the signal servers have access to" or "does not prevent a company from retaining information" they are talking about much smaller bits of data than people usually talk about. Email server: "your metadata is encrypted and private because our privacy policy says it is" Cryptographer: "your encrypted message could be read because there is a mathematical trail of the statistical distribution of keystrokes in the public record of battery use, so don't trust this with something important" But yeah, never trust what someone says. You have to look at the specificaiton and the implementation to know what's really going on. Signal said they do not prioritise nation-state anonymity back in the day. Back in that day, it was also reasonable to use a different network than Signal's for communications.