From HIPAA FTP:
HIPAA FTP is designed to keep your data secure through the entire data transfer and storage process, so there is no need to invest in expensive FTP Servers. HIPAA FTP simply works along side your existing Web or FTP server. Using advanced encryption technologies HIPAA FTP scrambles your client data files so that only you can ever view them. Dual-layer 256-bit encryption techniques like those used by CIA and FBI are considered unbreakable. Using a modern computer, it would take 149 trillion years to crack a 128-bit AES key. HIPAA FTP uses several embeded 256-bit encryption technologies including AES.