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RE: going back to stone axes
At 19:01 2/28/96, Bancroft Scott wrote:
>cme@cybercash.com (Carl Ellison) wrote:
>> I keep those in mind. I know how to write in ASN.1. Rule 1: don't
>> use SEQUENCE OF, SET OF, CHOICE, ....
>>
>> It's other people who don't know how to write in ASN.1. They *do* use
>> those constructs.
>
>This puzzles me. How do you express a list of items if you use
>neither SEQUENCE OF or SET OF? And how do you express a "branch" in
>the encoding/decoding based on a discriminant if you don't use a CHOICE?
Of course, if you really need to communicate and store an unlimited
length sequence, you need to transmit it somehow and therefore need to
encode it. You can elevate the sequence to the protocol and not try to
send it as a single message -- or you can break down and send an array
with a count of members. My preference is to send sequence elements
and let the surrounding protocol take care of delivering them -- not to
put them into a single message, but both methods work.
What I object to is the way ASN.1 makes it even easier to use a SEQUENCE OF
than to define a SEQUENCE. There is no ARRAY construct that I know of
in ASN.1 -- so I'm driven to use SEQUENCE OF.
The problem is that ASN.1 made it easy to define a Distinguished Name
as a SEQUENCE OF a SET OF a SEQUENCE of Attribute, Value. If you had
to define things with C or PASCAL structures, some of the pain of such
a baroque structure would have been visited upon the heads of those
specifying the structure and they might have had second thoughts --
used a simple byte string instead.
It is my serious, firm belief that a designer coming up with such a baroque
structure as the X.509 DN should be punished by his own process -- not
merely by the wrath of implementors saddled with using his output.
- Carl
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