From Sky Dancer Studios:
The Blowfish plug-in for Windows and Macintosh brings this popular, well-analyzed and tested encryption algorithm to FileMaker Pro 7, 8 & 8.5. (Blowfish just may be the MOST popular encryption algorithm in use today. It's currently used in over 150 different products including TiVo and has been incorporated into the Linux kernel starting with v2.5.47.) And it's completely cross-platform compatible. Encrypt on any Mac, PowerPC or Intel decrypt on a PC or vise-versa.