Sorry for all the questions but I've been away from crypto for a while and I'm looking for the best encryption program for exchanging email between Unix and Windows folks. I hope these questions are appropriate here. What do people generally think about S/MIME ? Is it well designed (strong and extendable) ? Is it convenient because its available in the popular email clients ? Is the most annoying thing about it that you have to pay for the keys ? Is there a way to self-sign keys ? SSLeay ? Are most people still using PGP ? If IDEA and MD5 (and PGP2.6.2) are not strong enough anymore, what are the Unix folks using ? Does the source for PGP5/6 compile to any target besides Windoze ? Thanks