Tor: From the Dark Web to the Future of Privacy

Aren't there ways to filter out untrusted nodes?

(Edit: I say this, but in reality I also think it's pretty safe to assume most are government controlled)

Nothing at all stops that, and there's scarce incentive for independent node operators. Indeed, it is commonly surmised that many node operators have a hidden incentive: they're explicitly trying to control enough nodes to deanonymize traffic because they are law enforcement agencies.

It seems, at the beginning of the 90s there were a lot of expectations in regard to DC-nets, considered to be a way better alternative to remailers of the time [1]. At least that's my impression after reading Tim May's FAQ (The Cyphernomicon) [2]. Any progress on this front?

[1]: https://en.wikipedia.org/wiki/Anonymous_remailer

[2]: https://hackmd.io/@jmsjsph/TheCyphernomicon

(with the understanding that I'm only speaking for what I found, not for the Tor project or the relay community)

Most of the people I spoke to saw themselves as providing a service - they wanted to help do something to bring a particular kind of future Internet about and found it rewarding to be a part of that. A number of them found the act of running a relay interesting and fun in itself - something they could get better at. Plus, membership of the relay community itself (especially now) is a kind of shared experience of community - and that's attractive to people in itself.

In terms of malicious actors, Tor does a lot to avoid this, from hunting down bad relays actively, monitoring the network as best as it can, continuously developing the algorithms which select routes through the network, and other mechanisms, like forcing relays to operate for a while before they get trusted with a lot of connections.

There's a lot in the book about this - it depends what you mean. Tor has a lot of social and technical design elements that try as best they can to minimise this risk. It would be pretty hard for intelligence services to compromise the Tor organisation in ways that meant they were deploying malicious code, for example. Plus, the way it's grown over the years has also given them some protections.

In terms of deanonymising people through surveillance (for example, by spying on the whole Internet and tracing you through the Tor network), Tor explicitly doesn't protect you against this. The decision was made early on - they switched all the high-security design elements to 'off' to make the network faster. They calculated that a hyper-secure network that was so slow no-one used it was less secure - i.e. made less privacy exist in the real world - than one that was less secure but used by millions, because that would give you a huge crowd of people to hide in. This gets really complicated - because you also want lots of different kinds of people using the network, so they can't tell if you're a drug dealer, an activist, a spy etc. just because you're using Tor.

Individual bits of major intelligence organisations can probably deanonymise you at some times, and not at others. The real question is if they can do so in a way that's dangerous to you in a sustained way, and if it's actually useful for them to do this. Usually, it's easier to do this through simpler mechanisms (bribing your friends, putting a camera in your bedroom, figuring out who you are etc.) than compromising the Tor network. Some security services absolutely will be researching and developing ways to deanonymise larrge numbers of Tor users at a given time - but in general, the budget for this is going to be quite high on a per-user basis (so you'd have to be a prime target for it to be worth it), and a lot of the complexity of the Internet geography makes this quite hard itself.

Ultimately, for any given high value target, there are usually easier ways to get them than through breaking Tor. In almost every case, a person will make a basic OPSEC error long before mass-scale traffic analysis gets them.