just wanted to suggest that biometrics are not wise for encryption
whatsoever. for one thing, they use a software mechanism to 'unlock'
and this lock can be bypassed. voiceprint, retina/iris scan,
fingerprints, dna, all of these things do not constitute a proper
password or lock for any data, for one thing you can't change them,
for a second thing, none of them generate a data stream which can be
used as a passphrase, it all goes through an identification process
and that only generates a yes/no answer. the usb key and the microwave
are the best way to go. a smart card would probably be just as good,
but not so cheap to implement.