I think they use this: http://www.akkadia.org/drepper/sha-crypt.html http://www.akkadia.org/drepper/sha-crypt.html which the version of crypt(3) in glibc. It

I think they use this: http://www.akkadia.org/drepper/sha-crypt.html http://www.akkadia.org/drepper/sha-crypt.html which the version of crypt(3) in glibc. It is almost the same as bcrypt. One difference is that it uses SHA256 or SHA512 instead of Blowfish. But that implementation has the same ability to expand the work factor like bcrypt. So I'd say that the algorithm they're using is slow and is designed to be slow