Encrypted Magic Folders is a very popular shareware title from PC-Magic. Magic Folders, its predecessor, was designed to intercept file IO requests in Windows and return "File Not Found" if the file was in a marked folder. It does this reasonably well, although booting into DOS exposes all the files. To solve this problem, PC-Magic chose to roll their own encryption. Reading the documentation about EMF's encryption is frightening: as one cypherpunk put it, "Smells like snake oil, looks like snake oil, it even has bits of snake scales in it." Here we show that EMF is susceptible to a known-plaintext attack that needs as few as 768 bytes. http://www.accessdata.com/emf_cryptanalysis.html -- Mike Stay Programmer / Crypto guy AccessData Corp. staym@accessdata.com