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RE: Best practice for data encoding?

2006-06-05 17:34:32
I agree that complexity breeds bug-prone implementations.

I wasn't around then; did anybody push back on SNMPv1 as being too
complex? http://www.cert.org/advisories/CA-2002-03.html is mainly
about SNMPv1 implementations. ;-)

dbh

-----Original Message-----
From: Steven M. Bellovin [mailto:smb(_at_)cs(_dot_)columbia(_dot_)edu] 
Sent: Monday, June 05, 2006 8:21 PM
To: David Harrington
Cc: randy_presuhn(_at_)mindspring(_dot_)com; ietf(_at_)ietf(_dot_)org
Subject: Re: Best practice for data encoding?

On Mon, 5 Jun 2006 20:07:24 -0400, "David Harrington"
<ietfdbh(_at_)comcast(_dot_)net> wrote:

Hi 

The security problems identified in
http://www.cert.org/advisories/CA-2002-03.html "Multiple
Vulnerabilities in Many Implementations of the Simple Network
Management Protocol (SNMP)" are not caused by the protocol choice
to
use ASN.1, but by vendors incorrectly implementing the 
protocol (which
was made worse by vendors using toolkits that had the problems).

If "Multiple Vulnerabilities in Implementations" were used 
to condemn
the encoding methods of protocols that have been incorrectly
implemented, then we would have to condemn an awful lot of IETF
protocols as being very (security) bug prone: 


Works for me....

More precisely -- when something is sufficiently complex, 
it's inherently
bug-prone.  That is indeed a good reason to push back on a 
design.  The
question to ask is whether the *problem* is inherently 
complex -- when the
complexity of the solution significanlty exceeds the inherent 
complexity of
the problem, you've probably made a mistake.  When the 
problem itself is
sufficiently complex, it's fair to ask if it should be 
solved.  Remember
point (3) of RFC 1925.

I'll note that a number of the protocols you cite were indeed 
criticized
*during the design process* as too complex.  The objectors 
were overruled.

              --Steven M. Bellovin, http://www.cs.columbia.edu/~smb



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