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Re: [saag] ASN.1 vs. DER Encoding

Nico Williams <nico@cryptonector.com> Thu, 04 April 2019 15:54 UTC

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Date: Thu, 04 Apr 2019 10:54:20 -0500
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From: Nico Williams <nico@cryptonector.com>
To: Benjamin Kaduk <kaduk@mit.edu>
Cc: Kazu Yamamoto <kazu@iij.ad.jp>, Peter Gutmann <pgut001@cs.auckland.ac.nz>, "Dr. Pala" <madwolf@openca.org>, "saag@ietf.org" <saag@ietf.org>
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Subject: Re: [saag] ASN.1 vs. DER Encoding
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On Tue, Apr 02, 2019 at 10:05:04PM -0500, Benjamin Kaduk wrote:
> > ISTR hearing about that, but the RFC does say:
> > 
> >   3.  Presentation Language
> > 
> >      This document deals with the formatting of data in an external
> >      representation.  The following very basic and somewhat casually
> >      defined presentation syntax will be used.
> > 
> > which is basically saying it's not a formal syntax.
> 
> We never bothered to remove the disclaimer, but the meaning is well-defined
> and that's really all you need to make it a "formal syntax".  That text
> seems unchanged from RFC 5246 (which really was a bit more slapdash about
> the formal definition).

Good.  An informal syntax can be good enough indeed.  And the use of a
formal syntax can be insufficient (e.g., Heimdal's ASN.1 compiler has
support for non-standard ASN.1 usage in RFC1510.)

Nico
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