[Cryptography] Crypto Standards v.s. Engineering habits - Was: NIST about to weaken SHA3?

Thu Oct 10 01:41:17 EDT 2013

On 10/9/13 at 7:12 PM, watsonbladd at gmail.com (Watson Ladd) wrote:

>On Tue, Oct 8, 2013 at 1:46 PM, Bill Frantz <frantz at pwpconsult.com> wrote:
>>... As professionals, we have an obligation to share our 
>>knowledge of the limits of our technology with the people who 
>>are depending on it. We know that all crypto standards which 
>>are 15 years old or older are obsolete, not recommended for 
>>current use, or outright dangerous. We don't know of any way 
>>to avoid this problem in the future.
>
>15 years ago is 1997. Diffie-Hellman is much, much older and still
>works. Kerberos is of similar vintage. Feige-Fiat-Shamir is from 1988,
>Schnorr signature 1989.

When I developed the VatTP crypto protocol for the E language 
<www.erights.org> about 15 years ago, key sizes of 1024 bits 
were high security. Now they are seriously questioned. 3DES was 
state of the art. No widely distributed protocols used 
Feige-Fiat-Shamir or Schnorr signatures. Do any now? I stand by 
my statement.

>>
>>I think the burden of proof is on the people who suggest that 
>>we only have to do it right the next time and things will be 
>>perfect. These proofs should address:
>>
>>New applications of old attacks.
>>The fact that new attacks continue to be discovered.
>>The existence of powerful actors subverting standards.
>>The lack of a "did right" example to point to.

... long post of problems with TLS, most of which are valid 
criticisms deleted as not addressing the above questions.

>Protocols involving crypto need to be so damn simple that if it
>connects correctly, the chance of a bug is vanishingly small. If we
>make a simple protocol, with automated analysis of its security, the
>only danger is a primitive failing, in which case we are in trouble
>anyway.

I agree with this general direction, but I still don't have the 
warm fuzzies that good answers to the above questions might 
give. I have seen too many projects to "do it right" that didn't 
pull it off.