problem of the Internet

authentication 
mentioned earlier under security and a second ago with spam
also often called `the identity problem' 
not to be confused with 'anonymity' which isn't on our problem list
like spam, more of a user issue, should solve outside the architecture
lack scalable, non-hierarchical trust models

<rant> 
btw putting a "solution" label on pgp is ludicrous
pgp(/gpg) remains an egregious tech transfer failure
perfect example of algorithms/standards far outpacing ability to deploy/administer 
if i pgp an email to one of my favorite security geniuses, it adds a week to RTT 
if he reads it at all
and that's only if i manage to have a version-compatible key
will admit i do same for ppt and doc files.  but why punish ascii?
why don't all client mail handlers support transparent authentication/encryption?  
even for an adolescent industry this component fails the smell test
and we're a little beyond that now anyway 
teenage scars notwithstanding, we are capable of cooperation
we shouldn't indulge this splintering unless it offers benefit
if anyone defends the genetic diversity of the pgp landscape i will personally flog them
</rant>