High level classes for dealing with S/MIME objects (RFC 3851).

There is one thing that is worth commenting about with these. If you're using AS2 on some other standard which specifies a different default content transfer encoding from RFC 2405, make sure you use the constructors on SMIMESigned and SMIMESignedGenerator that allow you to set the default ("binary" in the case of AS2 as opposed to "bit7" which is the default).