Given the lack of a widespread PKI for certificates, and the potential
need to secure DICOM media in a standard and non-proprietary way, here
is a DICOM CP for password-based encryption. See:
ftp://medical.nema.org/medical/dicom/cp/cp895_03.pdf
Not a panacea of course, but another option.
I have made a test file set using an implementation of CMS and PBE
that should match the CP 895 specifications. It is available at:
http://idisk.mac.com/dclunie-public/securedicomfileset.tar.bz2
if any of you are interested in trying to decrypt and unencapsulate it.
David