While a TLS uses the same key throughout a session, keys within a Signal session constantly evolve.
What are we defining as a "session" for Signal? The vast majority of TLS sessions exist for the duration of pulling down a web page. Dynamically interact with that page? New HTTP request backed by a new TLS session. Sure, there are exceptions like WebSockets, but by and large TLS sessions are often short.
Is a Signal session the duration of sending a single message? An entire conversation? The entire time you have someone in your address book? It doesn't seem like an apples-to-apples comparison.
I think the biggest thing here is that beyond just a session key (to make sessions secure from each other), this approach uses a rotating session key. That means each transaction in a sesssion is unique ensuring forward and backward secrecy.
I may have read it wrong plus cybersecurity is not my forte.
TLS can do key rotation too, it's just not needed in practice. The QUIC RFCs talk about it a bit, e.g. when using ChaCha20 the key usage limit is actually larger than the defined limit for transmitted data, making it only potentially relevant for AES.
9 Comments
ignirtoq@fedia.io · 12 pts · 311d
What are we defining as a "session" for Signal? The vast majority of TLS sessions exist for the duration of pulling down a web page. Dynamically interact with that page? New HTTP request backed by a new TLS session. Sure, there are exceptions like WebSockets, but by and large TLS sessions are often short.
Is a Signal session the duration of sending a single message? An entire conversation? The entire time you have someone in your address book? It doesn't seem like an apples-to-apples comparison.
jacksilver@lemmy.world · 6 pts · 311d
I think the biggest thing here is that beyond just a session key (to make sessions secure from each other), this approach uses a rotating session key. That means each transaction in a sesssion is unique ensuring forward and backward secrecy.
I may have read it wrong plus cybersecurity is not my forte.
The_Decryptor@aussie.zone · 4 pts · 311d
TLS can do key rotation too, it's just not needed in practice. The QUIC RFCs talk about it a bit, e.g. when using ChaCha20 the key usage limit is actually larger than the defined limit for transmitted data, making it only potentially relevant for AES.
Valmond@lemmy.world · 2 pts · 311d
Isn't asymmetric used for the handshake only? And then like AES or something which have evolving keys (and are quite quantum resistant).
AntiBullyRanger@ani.social · 3 pts · 311d
How is this different than SimpleX’s NTRU algorithm?
jacksilver@lemmy.world · 3 pts · 311d
I believe it's the same thing I noted in another comment - https://lemmy.world/comment/19924290
Basically session key vs rotating session key, but to be honest I only skimmed your link as it got dense fast.
AntiBullyRanger@ani.social · 3 pts · 311d
SimpleX has that with temporary addresses.
0x0@lemmy.zip · 2 pts · 310d
Do they still require a phone number?
BrikoX@lemmy.zip · 1 pts · 310d
Only for account creation, afterwards you can hide it and use username.