Re: Proper way to represent a NULL (no entries) CRL?

  >     The encoding rules in X.208 state that the SEQUENCE OF
  > construct may be encoded with zero entries, i.e., a zero length
  > sequence of whatever.  So, if we wanted to have that encoding (a zero
  > length sequence) represent a CRL with no entries, there would have
  > been no need to mark the SEQUENCE OF CRLEntry as OPTIONAL.  Since we
  > did mark this as OPTIONAL, I argue that a zero length sequence is not
  > the preferred encoding, although it might be a "legal" encoding
  > without the larger context presented by the RFC.
  > 
  >     In general, if any sort of ASN.1 construct is marked OPTIONAL,
  > I believe that the right encoding for it the omission of the
  > construct.  If there might be ambiguity in encoded data elements
  > caused by omission of an OPTIONAL element, then the overall data
  > structure is, I think, ill formed.  So I cannot be enthuiastic about
  > the encoding approach you adopted, in which a NULL placeholder is
  > encoded.
  > 

Steve,

Thanks for helping to clear this up. I note for completeness that the
DER's say, "if the value of a type is its default value, it shall
be absent." I infer from this that what has been decided is that
a null certificateList shall be the default (and is therefore omitted).

I will make the appropriate changes.

                Paul


---------------------------------
Paul Clark
Trusted Information Systems, Inc.
3060 Washington Road
Glenwood, MD 21738

E-Mail: paul(_at_)tis(_dot_)com
Phone:  301.854.6889
FAX:    301.854.5363
---------------------------------