re clipper chip technical details thus said djb silverton berkeley edu d j bernstein short summary of what bellovin says hellman says the nsa says there is a global key g plus one key u c for each chip c the user can choose a new session key k p for each phone call p he makes chip c knows three keys g its own u c and the user s k p the government as a whole knows g and every u c apparently a message m is encrypted as e g e u c k p c e k p m that s it the system as described here can t possibly work what happens when someone plugs the above ciphertext into a receiving chip to get m the receiving chip needs k p to get k p the receiving chip needs u c the only information it can work with is c if u c can be computed from c then the system is cryptographically useless and the key escrow is bullshit otherwise how is a message decrypted given the description of the algorithm given the only plausible explantion i can find is that k p must be agreed to out of bandwidth in advance by the two parties i e it s a standard shared symmetric key marc vanheyningen mvanheyn cs indiana edu mime ripem accepted security through diversion n theory which states that the public availability of good computer games is vital to maintaining system safety contrast security through obscurity
