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forest
forest
8:54 AM
@grsecurity @robertswiecki @_tsuro 300+ syzbot bugs mention netlink_sendmsg which is just subset of userns surface and we didn't try to cover it systematically (we don't cover whole lot of it). Did anybody try to cover all of it? It feels more like "Oh, it's Thursday, so I will look in that file,oh,another bug" :)
Tweeted by dvyukov on February 16, 2019 at 4:26 PM in reply to grsecurity
 
 
4 hours later…
forest
forest
12:45 PM
1
Q: Is Tor traffic using the TAP handshake vulnerable to retroactive decryption?

forestAssume an attacker with a record of Tor traffic between a client and guard has precomputed the 1024-bit Oakley group for Diffie-Hellman used in the TAP protocol. This would allow them to rapidly decrypt any recorded DH key exchange done over that group after an expensive but feasible (millions of...

attacks protocol encryption
^ In case anyone here has a good understanding of Tor's legacy TAP protocol.
 
 
6 hours later…
Steve
Steve
7:14 PM
@defalt - is this working? haven't used the chat before
 
defalt
defalt
working fine
@Steve So you met with Moxie Marlinspike in person?
 
Steve
Steve
cool, i'm not sure how much I can say while keeping the psuedo-anonymity of my SE account and of colleagues, but while the deniability is still in the underlying protocol, deniability is no longer advertised as a feature since newer features break the deniability
i think sealed sender is one, but i don't know the specifics
 
defalt
defalt
Which new feature exactly?
 
Steve
Steve
people are also working on better methods of deniable group messaging, since no true group KE protocols currently have deniability (although this point could be argued somewhat)
it's not so much that a single feature has broken deniability, but more that they no longer care about it and no longer consider that in their security proofs, which is why they believe some of the newer feature break deniability (although which one specifically i don't know)
 
defalt
defalt
Deniability in group messaging doesn't exist because each group participant signs the message. In pairwise messaging it is still there.
Maybe they were talking about deniability for groups and you assumed it for pairwise too.
 
Steve
Steve
7:24 PM
they have done studies to see what users care about most (such as sealed sender / metadata protection, deleting messages after a time, etc), and deniability has not been a feature most users care about, so it's no longer a priority for them
they have said specifically that deniability is no longer a priority for them and no longer consider it a feature
 
defalt
defalt
Deniability in pairwise messaging is still there though despite not being advertised by them. Pairwise messaging in Signal uses HMACs which can be forged by the sender with a valid key.
 
Steve
Steve
sure deniability at the protocol level exists, but any security/privacy feature at the protocol layer can easily be broken by features at the application layer. The signal protocol was written ~5 years ago? There have been many features added at the application layer since, and they no longer follow that same protocol exactly.
it's arguable whether Signal's original implementation of deniability really helps anyways since they don't offer a way to spoof messages like in most OTR software
 
defalt
defalt
OP in the question can easily deny that. One can just edit the message.db file of WhatsApp and reload the app
No need to forge HMACs as keys are cleared once the message arrives.
0
Q: Non-deniability of WhatsApp message

MasroorA is claiming that B has sent him a certain WhatsApp message. And if this incident is proven to be true, this will mean social and legal harm for B. But as a matter of fact, B has not really sent the message. What is the best way for B to deny that he has not sent the message?

whatsapp
 
Steve
Steve
sure but in a legal context plaintext messages are almost always considered proof anyways regardless of whether the underlying protocol is deniable or not. the ability for users to easily spoof messages directly in the application without any extra computer knowledge is what gives deniability a leg to stand on
 
defalt
defalt
@Steve I will message Joshua Lund, developer of Signalapp. He often comes on /r/Signal. I'm not going to mention about you 😅
 
Steve
Steve
7:39 PM
sure! i'll keep this chat open for a few days and watch if you post an update here. getting them to say anything about deniability can be difficult, so if you can get them to say more i'd be glad to hear it
 

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