Re: SSH in ECC Internet Draft

[Jon Green <jgreen%certicom.com@localhost>]

On Tue, 2006-10-10 at 11:17 -0500, Nicolas Williams wrote:
> On Wed, Oct 11, 2006 at 01:52:24AM +1000, Damien Miller wrote:
> > IMO that (some) ECC libraries happen to use ASN.1 is not a good reason
> > to use it as protocol element.
> 
> The draft defines one ASN.1 type ('curves', a SEQUENCE of OIDs) where
> existing SSHv2 constructs could be used instead.  The draft's other uses
> of ASN.1/DER do not require an implementation of SSHv2 to implement
> ASN.1/DER outside ECC libraries, but this one type does.

I don't think that we can just remove curves and send a name-list of
OIDs. Encoding and parsing a ASN.1 sequence is easier then encoding and
parsing a ssh namelist full of octet strings. 

So everyone is familiar with what an asn.1 sequence looks like:
[ identifier | length | oid | oid | oid | oid | ...
where each oid contains
[ identifier | length | oid data ]

The first problem with putting OIDs in name-lists is that the one of the
octets in the OID octet string may be 0x2C (ascii comma) which delimits
the list, so the OIDs will have to be encoded somehow before being put
into a standard namelist, or there has to be a new type of list
defined. 

Any list constructs I came up with seemed to be very similar to the
ASN.1 sequence of construct, so i decided to use it. Would including
some psudocode in the draft to encode and parse 'curves' maybe be a good
idea?

I like using the OIDs to identify curves since there is an already
existing IANA registry and we don't have to reinvent the wheel this
way. 

Cheers,
Jon Green