RE: I-D ACTION:draft-ietf-smime-cms-auth-enveloped-03.txt

[pgut001@xxxxxxxxxxxxxxxxx (Peter Gutmann)]

"Jim Schaad" <ietf@xxxxxxxxxxxxxxxxx> writes:

>I am having a problem seeing why having the attributes first causes a
>problem for algorithms that want them second.  All that is needed is that
>the encryption wrapper for the code understand that the attributes are going
>to come in first and hold onto them until later.  This is assuming that the
>encryption wrapper understands the difference between the body and the
>attributes.

What if the attributes depend on the data being processed (as Peter Sylvester
pointed out)?  By putting them first, you can't emit the first byte of data
until you've processed every other byte of data.  This is why current CMS
practice puts the attributes last.

Peter.