Hash functions are generally designed to be fast. For the very concern you mentioned some people prefer using http://en.wikipedia.org/wiki/Bcrypt http://en.wiki

Hash functions are generally designed to be fast. For the very concern you mentioned some people prefer using http://en.wikipedia.org/wiki/Bcrypt http://en.wikipedia.org/wiki/Bcrypt to store the password, which on the other hand is designed to be slow.