[fc-discuss] Financial Cryptography Update: OpenPGP suports any Trust Model that you desire!

[iang@iang.org]

 Financial Cryptography Update: OpenPGP suports any Trust Model that you desire! 

                           December 17, 2005


------------------------------------------------------------------------

https://www.financialcryptography.com/mt/archives/000612.html



------------------------------------------------------------------------

[editorial note - this is a guest post by Ed Gerck]

James A. Donald wrote:
>     --
> From: 	      Werner Koch <wk@gnupg.org>
>
>> You need to clarify the trust model.  The OpenPGP
>> standard does not define any trust model at all.  The
>> standard merely defines fatures useful to implement a
>> trust model.
>
>
> "Clarifying the trust model" sounds suspiciously like
> designers telling customers to conform to designer
> procedures.  This has not had much success in the past.
>
> People using PGP in practice verify keys out of band,
> not through web of trust.


James,

Yes. Your observation on out-of-band PGP key verification is very
important and actually exemplifies what Werner wrote. Exactly because
there's no trust model defined a priori, uses can choose the model they
want including one-on-one trust.

This is important because it eliminates the need for a common root of
trust -- with a significant usability improvement.

If the web of trust is used, the sender and recipient must a priori
trust each other's key signers, requiring a common root of trust --
that may not even exist to begin with.

So, instead of worrying about what trust model PGP uses, the answer is
that you can use any trust model you want -- including a hierarchical
trust model as used with X.509.

Jon Callas and I had several conversations on trust in May '97, when
Jon visited me for two weeks while I was in Brazil at the time, I think
before the OpenPGP WG was
even working on these issues. This is one of the comments Jon wrote in
a listserv then, with a great insight that might be useful today:

  As I understand it, then, I've been thinking about some
  of the wrong issues. For example, I have been wondering
  about how exactly the trust model works, and what trust
  model can possibly do all the things Dr Gerck is claiming.
  I think my confusion comes from my asking the wrong
  question. The real answer seems to be, 'what trust model
  would you like?' There is a built in notion (the
  'archetypical model' in the abstract class) of the meta-
  rules that a trust model has to follow, but I might buy a
  trust model from someone and add that, design my own, or
  even augment one I bought. Thus, I can ask for a
  fingerprint and check it against the FBI, Scotland Yard,
  and Surite databases, check their PGP key to make sure
  that it was signed my Mother Theresa, ask for a letter of
  recommendation from either the Pope or the Dalai Lama
  (except during Ramadan, when only approval by the Taliban
  will do), and then reject them out of hand if I haven't had
  my second cup of coffee.

Cheers,
Ed Gerck 

-- 
Powered by Movable Type
Version 2.64
http://www.movabletype.org/