Avoid timing attacks and fix #24

[leandro-lugaresi]

Time attacks can be used to improve one Brute Force attack More info can be found here: http://blog.ircmaxell.com/2014/11/its-all-about-time.html http://sakurity.com/blog/2015/07/18/2fa.html

This comparison will also avoid the problem of leading zeros (#24) :)

[esolitos]

I reviewed the code and it looks fine to me!

[Conver]

+1

[renini]

:+1: merge?