Yes you can, its called Cryptography, and password guessing attacks like Dictionary or Brute force attacks, There are many tools available to download for that one is called "cain & abel" i know i refer to that program alot but it can do alot like it has cracker, wireless sniffer, sniffer, APR injections, cookie modifier and capturer, VOIP sniffer and alot of different hash calculators, you can get that from and its free to download and clean. If you ever need to take text to bnary and base64 or hexadecimal or others go to this site