Is HSDir based attack is still possible nowadays? +Need some info

Question

I've read some information from 2014-17 about attacking possibilities which have or had nodes are called ''HSDirs''

At first what i need to know, HSDir node it is also ''exit'' or third node from client, isn't it?

At second, as authors of researches have said, malware HSDirs can be able to (or were be able to) know V2 onion's adresses, which clients connecting to, but what about user's IP? Can they deanonymize client/user or easily compare client request IP's and URL's of onions?

At third, is V3 so much better than V2? Because as far as I know from 2013 documentation, only 2 nodes (first and third) needed to easily deanonymize V2 onion user. Or in 2020 2 nodes are not enough?

Thank you so much. Shukriya

Answer 1

The name HSDir comes from "hidden service directory". These HSDir nodes make up something called a distributed hash table. This is somewhat similar to a distributed phone book where you look up information about a hidden service from these HSDir nodes. You do not actually connect to the hidden service through this HSDir. Instead you download the hidden service's descriptor (like a phone book entry) from the HSDir so that you can learn how to contact the hidden service (through one of the hidden service's introduction points). Your final connection to the hidden service is through a different relay called the rendezvous point. So while the HSDir node is generally a relay like any other (so you can use it as any hop in a circuit), it has nothing to do with actually connecting to the hidden service.

With V2 hidden services, the HSDirs can see the actual names of the hidden services. If we use the phone book analogy, these HSDirs can see the phone book entries that they're storing. With V3 hidden services, these HSDirs cannot see the names of the hidden services because of the use of a blinded signing key for the descriptor.

As far as I know V3 hidden services are not any more safe against traffic timing/analysis attacks than V2 hidden services.