Public Key Infrastructure: An Artifact...

[Bram Cohen]

On Sat, 18 Nov 2000 Lynn.Wheeler at firstdata.com wrote:

> note also that current SSL infrastructure is vulnerable to things like domain
> name hijacking; aka, at least part of SSL protocol is to make sure that you
> really are talking to the host that you think you are talking to ... i.e. the
> SSL certificate contains host/domain name (all this, in theory because of
> weaknesses in the domain name infrastructure) ... and when SSL goes to check
> something in the certificate ... it is checking the hostname/domainname against
> the hostname/domain name that the browser is using.
>
> However, SSL-certificate issuing CAs have to rely on the domain name
> authoritative infrastructure with regard to issuing SSL-certificates & domain
> name ownership issues ... this is the same authoratative infrastructure that
> supposedly can't be relied on and justifies having a the whole SSL-certificate
> infrastructure to begin with.

To be fair, this sort of attack is much more involved and must be planned
much farther in advance.

> In any case, the domain name infrastructure has been looking at ways to beef up
> the integrity of its operation ... like having public keys registered as part of
> domain name registration. Now, if domain name infrastructure is going to use
> public key registration as part of beefing up its integrity ... that would
> medicate  much of the justification for the SSL-certicate infrastructure.

This would remove one of the more serious barriers to running an SSL 
site - the Verisign protection money.

The problem with all of these things is that they are still based on
creating an association between a domain name and a key, when in fact what
you want is an association between some abstract concept of a counterparty
which exists in an end user's mind (like, say, amazon) and the ownership
of a machine that user's browser is talking to.

Unless that problem is fixed, man in the middle is hardly made more
difficult - for example, Mallory could break into some random machine on
the net and steal it's public key, then hijack local DNS and when someone
goes to amazon.com redirect them to amazon.hackeddomain.com, and then
proxy to amazon.com - now even SSL says the connection is safe.

-Bram Cohen