Re: [xcbf] Bi-weekly XCBF telecon

[John Larmouth <j.larmouth@salford.ac.uk>]

Tyky, I have been up to my ears for the last couple of weeks getting the 
ASN.1 amendments finalised, but I will prepare a revised draft (with 
comment marks) early next week for consideration.

The attached picture (drawn by a colleague, but he said I could send it 
to the list) is useful background to any discussion.

It shows the basic structure of the XCBF spec from an encoding point of 
view.

Nodes in red are in the Open Typ, and need to be encoded with a 
canonical encoding rule (I think CXER is required, not DER) for the 
purposes of generating octet strings for the digital signature or MAC, 
which are a separate branch in the enocding.

The green is DER encoded.

The black is shown as XER (non-canonical) but I believe the intent is to 
allow BER as well (non-canonical).

A basic problem is that the encoding of an Open Type is always the 
encoding of the enclosing type, so you can't go from black to red in the 
actual encoding on the line.

I am also unclear whether, if BER is used instead of XER, the red 
material becomes DER for the purposes of the digital signature and MAC, 
or remains CXER.  I believe the latter is the intent.

So ...... I will prepare a draft in which the outer-level black AND the 
open type red can be either BER or BASIC-XER with an anticipation of 
EXTENDED-XER to allow the BASE64, and the MAC and digital signature 
always being computed on the CXER encoding of the contents of the open type.

This may or may not be what people want, but at least it will give us 
concrete and complete text to consider in our teleconference.

John L

PS  I will shortly now provide the promised tutorial summary of 
EXTENDED-XER.  The final documents were sent for ISO ballot early 
morning my time (after I had been up to 1am trying to get them done).
But I won't promise this for Friday, but will start to do something on it.

Tyky Aichelen wrote:
> 
> 
> 
> Hi Team,
> Thanks to you all for your input on the subject. So here is the proposal re
> Telecon:
> Bi-weekkly XCBF telecon
> Time: 9:00AM Pacific Time
> Length: 1-hour
> Starting on May 23, 2003, going through the end of the year.
> Telecon Agenda: I will post each telecon's agenda on the Web site ahead of
> time prior to the call day, so folks would have enough time to be prepared.
> Submit to me any item you would like to be covered and I will include them
> in the agenda.
> Minutes: Right after each telecon, I will post its minutes on the site.
> Cancellation or Addition: If needed, we will jointly decide on cancelling a
> specific telecon on a specific Friday (due to holidays, not necessary,
> conflicts, etc.) or on adding a special call (for rush period of editing,
> issues to be resolved asap, meeting dealine, etc.)
> 
> Jamie: We start the call on May 23, so we have enough time to prepare the
> agenda and so you can attend. I know you cannot make at 9:00 AM PT this
> Friday May 16 (tomorrow).
> 
> Team: Any suggestions for May 23 agenda. How about we have an assessment of
> where we are at now with the CS and where we want to go, what to do next.
> 
> Best regards,
> Tyky Aichelen
> 
> 
> 


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