
From the limited details released so far, It seems that the clipper chip 
system must employ some sort of public key cryptography. Otherwise, the key 
management problems inherent to symetric ciphers would make the system 
unworkable. It probably has some sort of public key exchange that takes place
at the start of each call. Thats how they would identify the private key in 
their data base?

This means that either the NSA has developed some non RSA public key 
algorythm or the feds have decided to subsidize PKP & RSADSI. The former is 
rather an exciting posibility since keeping the algorythm secret while making
chip implimentations widely avalibe will be exceptionally hard. If the feds
are forced to make it avalible in order to gain public acceptance than that 
could break RSA's stranglehold on public key crypto in the U.S.   

As for my impressions of the whole scheme It seems that instead of trying to
ban strong crypto, they are trying to co-opt it. Their contention that they 
need to keep the algorythm secret to protect the security of the key
registration suggests possible inherent weakness to the algorythm. More likely
is that they dont want anyone constructing black market devices which dont 
have the keys registered. Anyone else notice that in their Q&A session, they
talk about releasing the keys only to people with proper autiorization but
carefully dance around stating that the keys will simply have to be supeonaed.
They seem to be trying to keep open the posibility of obtaining keys without 
court order even though tapping a phone line requires one. Also pick up on 
their implicit threat of eithe accept this or we'll ban strong crypto outright?
I dont trust this plan at all and plan to oppose it in all (legal) ways
possible.