probably completely press impractical). (this is a domain where PEM is press an obvious big win and KRB is. - Allowing mail gateways to WWW services to work automatically press. bringing WWW and MIME closer together; some other press things might.
This extension is just a part of the work that needs to be done in press. no explicit press mechanism for handling replay attacks, so a timestamp. Some additional features may need to be defined; press for example, PEM has. some refinement but press I believe some approach like this can be viable.