Truesign doesn't use PoW. The bot detection works by collecting network and browser signals.
The PoW solutions I've seen out there just add 1-2 seconds of delay before granting access to the whole site. It could work against random unsophisticaed crawlers but I don't see how that can stop determined bots.
The PoW solutions I've seen out there just add 1-2 seconds of delay before granting access to the whole site. It could work against random unsophisticaed crawlers but I don't see how that can stop determined bots.