bcrypt is a hashing algorithm used for authentication (transforming a plaintext password to a set of deterministic but random bits, for storage and future compa

bcrypt is a hashing algorithm used for authentication (transforming a plaintext password to a set of deterministic but random bits, for storage and future comparison). The idea being that it is very CPU intensive. Thus dictionary like attacks against it are not very effective, because it requires lots of time to calculate single hashes. They removed code that sped it up (cpu register optimizations it looks like), which is silly for multiple reasons. The most important one being attackers can just download the bcrypt code and add this back in.