If it's encryption software, browse around the Cryptography class: http://www.uspto.gov/go/classification/uspc380/sched380.htm http://www.uspto.gov/go/classific

If it's encryption software, browse around the Cryptography class: http://www.uspto.gov/go/classification/uspc380/sched380.htm http://www.uspto.gov/go/classification/uspc380/sched380.htm After you find the subclass, click on the red P to get a list of the granted patents. But note that these are only the patents that have been granted, you still have to check out the latest patent applications. This system can seem a bit confusing, which is why there are so many service providers who specialize in this area. But with a little elbow grease, you can get through it yourself. The defect with resources such as freepatentsonline is that they do not have the whole database. A good alternative is http://www.patentlens.net/patentlens/simple.cgi http://www.patentlens.net/patentlens/simple.cgi If you are handy with regexpr/sexpr/xml search tools, you may want to take a look at the raw patent data from the FTP archives as well as the Patent Grant Red Book. More info at http://www.uspto.gov/web/menu/patdata.html http://www.uspto.gov/web/menu/patdata.html From the raw data you could roll your own patent search engine. Please also note that as a general habit you should research the academic periodicals in the Crypto arena to see if anyone else has published any information about the topic in question. If so, you will need to include it in 'prior art.' If you are very serious about the process, check with a local attorney. If the prices quoted seem out of your ability, contact the nearest (and largest) law school in your area. Speak with the IP faculty who can point you in the right direction for local counsel.