I don't care very much but tend to be conservative, thus A.
There is also a third option: A+B and changing the tag of the
It is not only SignedData, AuthenticatedData also has the A encoding
as far as I understand, see below.
I am not sure but why the AuthAttributes are there before the content?
Although a messagedigest is not part of the AuthAttributes, this means
that whene an AuthAttributes for SignedData or AuthenticatedData
requires reading the data, this gets difficult to use. I am thinking
for example a timestamp as attribute.
Russ Housley wrote:
I'd like to add one point. Please look at section 9 of RFC 3852. The
authenticated attributes in AuthenticatedData follow choice B).
Russ, are you sure?
If authAttrs field is present, the content-type attribute (as
described in Section 11.1) and the message-digest attribute (as
described in section 11.2) MUST be included, and the input to the MAC
calculation process is the DER encoding of authAttrs. A separate
encoding of the authAttrs field is performed for message digest
calculation. The IMPLICIT  tag in the authAttrs field is not used
for the DER encoding, rather an EXPLICIT SET OF tag is used. That
is, the DER encoding of the SET OF tag, rather than of the IMPLICIT
 tag, is to be included in the message digest calculation along
with the length and content octets of the authAttrs value.
At 01:34 PM 3/27/2007, Turner, Sean P. wrote:
At IETF 68, Russ Housley presented an summary of the
Authenticated-Enveloped-Data content type (the slides can be found at
). There was one open issue (the last slide) that dealt with the
encoding of authenticated attributes. It was discussed at the
meeting; however, responses from a wider audience (i.e., this list)
is necessary. Please indicate your preference on whether:
A) The encoding of the authenticated attributes should be done
exactly the same as in SignedData.
B) The encoding of the authenticated attributes should use the
encoding that will be transmitted.
We are soliciting feed until 10 April 2007.
Description: S/MIME Cryptographic Signature