some questions was revised summary here is a revised version of my summary that corrects some errors and provides some additional information and explanation thank you very much after reading the text some distinct questions arised to me which i guess will also be asked by other people perhaps would it be interesting to find an answer to these questions the clipper chip a technical summary n a bit serial number this length is subject to change shorter or longer once the session key k is established the clipper chip is used to encrypt the conversation or message stream m digitized voice the telephone security device feeds k and m into the chip to produce two values e m k the encrypted message stream and e e k u n f a law enforcement field which are transmitted over the telephone line the law enforcement field thus contains the session key k encrypted under the unit key u concatenated with the serial number n all encrypted under the family key f the law enforcement field is decrypted by law enforcement after an authorized wiretap has been installed first question when will the lawenforcmentfield be transmitted and how does the remote clipper chip handle it is it transmitted periodically in the stream of encrypted blocks or just at the beginning does the phone at the other side discard those packets via a protocol whatsoever or tries it to turn them into voice output which would not be disturbing at the beginning of a session a trusted agent from each of the two key escrow agencies enters the vault agent enters a secret random bit value s into the laptop and agent enters a secret random bit value s these random values serve as seeds to generate unit keys for a sequence of serial numbers thus the unit keys are a function of secret random bits where each agent knows only second question why why is such a strange procedure used and not a real rng this turns those s s in a kind of bottleneck for system security when law enforcement has been authorized to tap an encrypted line they will first take the warrant to the service provider in order to get access to the communications line let us assume that the tap is in place and that they have determined that the line is encrypted with the clipper chip the law enforcement field is first decrypted with the family key f giving e k u n documentation certifying that a tap has been authorized for the party associated with serial number n is then sent e g via secure fax to each of the key escrow agents who return e g also via secure fax u and u u and u are xored together to produce the unit key u and e k u is decrypted to get the session key k finally the message stream is decrypted all this will be accomplished through a special black box decoder so no technical provision will be taken to place a timeout on these warrants this would be a unique possibility to realize such a technical restriction by letting the escrow agencies perform the decoding of the session key just take modem lines instead of secure fax is this such a bad idea a successor to the clipper chip called capstone by the government and myk by mykotronx has already been developed it will include the skipjack algorithm the digital signature standard dss the secure hash algorithm sha a method of key exchange a fast exponentiator and a randomizer a prototoype will be available for testing on april and the chips are expected to be ready for delivery in june or july wow how does the randomizer work are the sha and key exchange secret or publicly known key exchange is dh i guess it seems that those who are opposed to this chip shall have a tough time your government realy means to act friendly greetings germano caronni instruments register only through things they re designed to register space still contains infinite unknowns pgp key id germano caronni caronni nessie cs id ethz ch fd ccf f da ea c dd f
