http://blog.zorinaq.com/my-experience-with-the-great-firewall-of-china/
tl;dr: Someone tests ExpressVPN and other methods to get past the Great Firewall. Turns out ExpresVPN uses weak 1024bit RSA keys, which can probably be cracked by about $10 million worth of specialized hardware... and ExpressVPN actually fixes the problem.
@pete
The article, including the claim of $10m to crack 1024RSA, was from 5 years ago.
Not an insignificant detail.
Probably just me, but I hold it against them that in 2016 they used 1024RSA keys, while I already used 4096RSA keys by then. And I am/was not running a business where ppl think they get (extra) security.
@pete interesting article... frankly had no idea they "allow" VPNs at all, it should be easy to block them, don't VPNs use a fixed (or infrequently updated) pool of IP addresses?