HIPPA's official web site is where you will find your answers:
http://www.hhs.gov/ocr/privacy/index.html. Storage and security of the files with medical information is extremely important. If you are transcribing and it is a code to a person and not their name, address, social security numbers, etc., then you are well protected. How you transfer files back and forth and how you store them are critical. I strongly recommend that you check out the web site and become extremely familiar with the regulations. The regulations change often and you are required to keep up with them.