xml-dev - Re: ASN.1

[David Brownell <david-b@pacbell.net>]

> > >Third, BER is not the only standardized encoding ... there's also DER, which
> > >is a bit more widely used.  (X.509 certs use BER, but most everything else
> > >uses DER ... think of BER as "canonical DER".)  Choices, choices.
> 
> I would have thought DER was "canonical BER".  DER stands for
> Definitive Encoding Rules, doesn't it?

"Definite", not "Definitive" ... but right, X.509 uses DER so there
is only one way to encode, and DER subsets BER by removing options.

Switching those two was a test to see who else knows their stuff!  :-)


> > Never heard of DER.  X.500, SSL, LDAP and SNMP all use BER. 

X.509 and various other systems (including SSL) use DER.  Those of
us who've implemented them know it all too well.


> >	 BER is really
> > quite simple (or at least the subset needed by the above protocols).  Open
> > Source libs to encode/decode BER abound.

I've seen many of them, and have been amused at how inconsistent their
bug sets are.  If you want "simple" look at XDR, which has many more
such open source libs, generally without any bugs.  (Of course in both
cases you need to like binary data formats.)

- Dave

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