They can donate some money to charities running Tor nodes while they're at it, or run some themselves.
Iran tried to censor Tor too, but it's pretty much impossible to do so fully. At least the Tor devs are usually on top of it, while Signal is inexperienced dealing with things like this.
The fact that it is?
There are secret bridges and Tor is able to disguise its traffic as other 'legitimate' protocols.
My ex moved to China, and she told me that the only people who say Tor can't be blocked are people who have never lived in a country where the government is actively trying to block it. Just because you can connect to it doesn't mean you won't get a knock on the door in a month asking why.
Iran can block these proxies, too, but this way there isn't any centralized listing of proxies. This proxy setup is simple enough that a single person could run a proxy for a few dozen of their friends, and the Iranian government might just never find out about it.
I fear that some naive Western expat will participate and find themselves in a hostage. Many countries in this don't have any treaties with Western nations, they dont have high regard for human rights either.
https://2019.www.torproject.org/docs/bridges.html.en#Pluggab...
One could use censorship evading VPNs like Tor, Lantern, Shadowsocks, Psiphon in addition to using these proxies. They all have different evasion mechanisms.
The thing that works for user-run proxies is, it is like a hydra, you censor one proxy another crops up.
Regardless, I hope this does actually end up working, and allows Iranians to use Signal without a prolonged cat-and-mouse game.
The TLS proxy signal just advertised uses plaintext TLS SNI header to determine where to route the packets, which makes it really trivial to detect and/or block. The same cannot be said about tor.
Signals TLS proxy is naive compared to obfs4, but at it’s core it’s a similar solution.
So no, it's not 'blocked'. They're just trying. Mostly by blocking bridges they know of.