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Re: SDSI and key distribution

Wei Dai wrote:
> Earlier I argued that the key distribution problem is really not much of a
> problem.  People can simply use hashes of their public keys wherever they
> now use their e-mail addresses.  However I realized there is at least one
> scenario where this might not work well:
> Alice and Bob meet at a party.  They want to exchange public keys, but
> Alice forgot to bring her business card.  Memorizing a 160-bit hash can be
> somewhat cumbersome, even if they are nicely encoded.
> Let me propose a simple solution to this problem: a secure public database
> that allows lookup using arbitrary octect strings.  Each entry in the
> database contains a Principal: object, and is indexed by a string that
> serves as a short hand for the principal.  When the database is first
> created, the popular index strings can be auctioned off.  Afterwards, they
> are allocated on a first come, first serve basis.  Alice can register her
> public key under the string "Alice", or if that string is already taken,
> any other available index she likes.  Let's call this database ARB.  When
> she meets Bob, she can just say, "My public key is ARB!!'s Alice."
> The idea here is that ARB's local names are completely arbitrary and does
> not necessarily have any relation to any other names (e.g., trade marks or
> legal names).  They serve only as indices to the Principal: objects.

   Uh, building such a database is _exactly_ what I meant by the "ket
distribution problem." Making such a database secure is not easy. Making
it scale, and coordinating the administration of such a database, are
also very important.

   As long as you have such a database, why not just use e-mail
addresses as the index, instead of creating yet another name space? You
must admit that this is by far most convenient for users.

   There's a good chance I'll be working on the key distribution problem
this summer.


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