PKI creed (was Re: Trustworthy contacts)

[Dave Bird]

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In article <00a001c01f01$7c7c1970$ad269fd4@fortytwo>, Brian Gladman
<brg@gladman.plus.com> writes
>From: "Dave Bird" <dave@xemu.demon.co.uk>: 
>>
>> In article <3.0.5.32.20000914063541.0082ec40@spiritone.com>, Carl
>> Ellison <cme@acm.org> writes
>> >This is a mistake Diffie and Hellman made in their original paper -- that
>> >has been propagated down through the decades.  They said to build a
>> >directory of names to keys, then you can look me up in the directory, get
>my
>> >key and send me a message.  Fine theory.  How do you find me in the
>> >directory?  You can't use a name.  There are too many Carl Ellison
>entries.
>>
>>  Well, I have argued a model in which we deal with identity much as we
>>  do in the everyday world but then add public keys on top.  For example,
>>  to find out who the hell you were in practical terms, I would ask a
>>  couple of people I know at ACM.  I would expect your key to be signed
>>  by the ACM organisational key and, if I didn't have that, I'd ask
>>  my friends to send me a signed copy of the ACM key or key fingerprint.
>
>I agree - we must evolve from where we are.  In the real world we have lots
>of well developed human ways of making sure that those with whom we are
>exchanging information are who we think they are.  And provided we can
>manage our respective local namespaces in a way that provides for such human
>intervention and control we are probably not going to make too many
>mistakes.

 I general terms it seems to me that when I want a new contact for
 say, the Fire Safety Office in Camden, there are public alphabetical
 or specialised directories where I can get it.  I admit the additional
 guarantee of a "confidential line to..." requires something extra in
 terms of how authentication is generated and distributed,  nut nothing
 that impossible.
>
>But it is not obvious (to me at least) how we can engineer our systems in
>such a way that this can happen locally and yet we can still achieve a
>significant level of global interoperability.  SDSI and other approaches in
>which wider relationships are established between entities in local name
>spaces (i.e. my John Smith = your John Smith) are more attractive than
>global top down directories in that they are a better match to how the real
>world works but do they scale up in a way that can meet global needs?
>
>Turning to electronic commerce, a central issue is that of deciding where
>identity really matters.  Since, in essence, the buyer wants the goods and
>the seller wants the money, the critical issue for both is whether these two
>elements of transactions can be underwritten in some way. While identity may
>matter to the organisations that do this underwriting, it seems to be of
>little direct relevance for the transactions themselves and this suggests
>that these would be much better organised around PKC used to provide
>transaction authorisation rather than the identities of the participants.

 As you say, in finding a supplier for (e.g.) purple plastic dinosaurs
 there are credit liability issues.... somebody has to stand guarantor
 that I will pay, that he will supply, that he can be sued if he 
 supplies dangerously defective product that harms my customers.
>
>At the moment it seems that e-commerce companies don't have to worry much
>about the identity of customers because their interest - getting paid - has
>been underwritten by the banks.  But the growing volume of fraud in
>'customer not present' transactions and the resulting 'claw backs' may
>change this and, as Quentin has indicated, there is now evidence of mounting
>pressure to move this risk onto consumers.
>
>Looking at consumer interests in identity, my gut feeling is that consumers
>do have an interest in the identity of the company with which they are doing
>business.  In my e-commerce transactions I am much happier working with
>companies I know and trust rather than ones I am dealing with for the first
>time.  But what I really want is to know is that the company I am dealing
>with on my N+1'th visit is the same company that I dealt with on visits 1,
>2, ..., N since confidence that this is a single relationship allows me to
>develop trust in the company over time - if I have made 100 transactions
>with them without any problems I am likely to be pretty confident in success
>with transaction 101 (I admit that this confidence might not be justified).
>
>This relationship does not rely on identity as we normally think of it but
>simply identity in the sense that 'the entity I am dealing with now is the
>same entity I have dealt with N times before' and this can be accommodated
>by the exchange of verification keys for our respective signatures.  But at
>least some of the keys involved here have to be long lived since they have
>to be capable of spanning, directly or indirectly, all the individual
>e-commerce transactions that the company and I undertake over an extended
>period in order to have confidence that there is just one relationship on
>which trust is built.
>
>The problem with this is not the public keys, since the keys we have
>exchanged do not need to be public - it is the secret keys, since we are
>depending on their long term secrecy.  And here I am not convinced that we
>have the technology to provide for this when these keys are being
>manipulated by the sort of computer systems that we typically use at the
>moment.
>
>It will be some years before internet connected home PCs will be able to
>sustain such levels of secrecy and this means that someone will have to
>underwrite the resulting risks if e-commerce from home is to take off.
>Consumers are already very reluctant about this and I can't see the banks or
>merchants sticking with this without some significant security improvements.
>It would be nice to believe that company e-commerce sites can meet such
>requirements but recent examples from both banks and large companies give us
>little basis for confidence here.
>
>In my view the public is right to be worried about the safety of e-commerce
>but what is the government doing to overcome such concerns?  Well, it talks
>a lot about e-commerce but it actually seems to spend its time undermining
>it with things like GAK in RIP.
>
>In other words, implementing non-solutions to non-problems but making
>extremely difficult, real problems even worse than they already are in the
>process.
>
>    Brian
>
>
>

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