re more technical details hmm followup on my own posting well who cares first let me try to work out the facts that we get to know about the clipper chip from what hellman and denning were able to tell us the chip itself is not confined to digital telephony but performs general encryption in a symmetric manner the chip supports cfb ofb ecb and whatever the fourth mode of operation for des is the algorithm consists of rounds of whatever and takes bit keys input data seems to be bit yes so if two people want secure communication whatever that means when clipper is involved they have first to agree on one secret key or is it one key per direction they can exchange this key via dh schemes or however somehow the two feed their so won secret key into the clipper chip which is now ready to work the clipper chip carries an unique serial number bit s and key bits these key bits seem to have been gained by encrypting the serial number with seed bits the seed bits seem not to be stored in the chip at beginning of communication and perhaps at certain invtervals whithin before sending the fist real bit output of the first encryption the clipper chip put s out packets i guess which represent the serial number and the session key this might look like x e k chipkeyk k serial number where x is a transformation of these packets involving a family key this family sp key is equal for all chips x might be a simple xor after that the digital phone call can be done as usual every packet being encrypted and decrypted by clipper denning describes how k and k shall be generated using a seed of bit s now leaving alone politics which does not concern me as much as you not being an american citicien tm there are some weak points in this scheme which might be exploited by several parties as far as i know about the generation of k k s and s look like the obvious backdoor they could be used to generate the chip keys by knowing the serial number and also the family key of the chip i really can t imagine why these seeds would be needed otherwise as true random sources for the generation of the k k can be bought for not to much money then the escrows each of them will get bit of a bit key security could as little as existant be maximized by giving them bits each which have to be xored together to give the k k now let s simply assume the escrows are trustworthy and can t be fooled by criminals or law enforchemnt agencies and there will be no quarrel between escrows and l e a which would hinder the l e a in doing their duties and so on and so on once the keys are surrendered the corresponding chip is compromised forever not very clever imho how about sending in the encrypted session keys for each phone call that the police or whoever want s to listen to escrows could then simply decode this session key and send it back to police and would naturally not do this after the warrant has expired this would be a better technical solution but i guess politics will not work that way apparently as miss dennings stated the only one performing actually decodes of intercepted messages shall be the fbi great so local guys can not inter cept understand your traffic anymore does this mean that the fbi monopolizes the right to do legal wiretaps how is law over there i have no idea who is allowed to tap and who not this certainly means that watched communi cations will be routed automatically from the service providing company to the fbi if the communicaiton is a watched one and this means as far as i understand it that the family key has to be known by each switching company and those providing cellular phone servies etcetc so the family key will not be very secret and thus serial numbers of calls will be readable by anybody who cares i like traffic analysis what do you guess what happens if you use the chip in ecb mode and the first few packets of the chip are somehow lost or garbled so the session key would not be actually broadcasted over the line hmmm shouldn t be so difficult to do that and now a last point for the other side after all i have read and heard about clipper not the programming language for dbase is it it seems to have many advantages which shold not be overseen now an afterthought to your rights please note that i have no idea what i am talking about from grady netcom com ef amendment congress shall make no law respecting an establishment of religion or prohibiting the free exercise thereof or abridging the freedom of speech or of the press or the right of the people peaceably to assemble and to petition the government for a redress of grievances if this text is actually in your bill of rights who can overrule this but freedom of speech is not secrecy of speech maybe you need to extend your amendment to cover information and communication too i am not very sure in what position your government actually is legally when it tries to ban cryptography and arms amendment say you may have them but not under what conditions hmm tricky situation actually it will make not much sense to discuss that topic in sci crypt discussion of technical details and vulnerabilites of the system are highly suggested and appreciated friendly greetings germano caronni disclaimer everything in here is derived from things i heard and read from other persons so everything could be wrong all opinions and thoughts in here are mine and subject to change without further notification no warranty neither implicit not explicit etc etc etc ad nauseam p s please don t ask me about political opinions as i might not bother to re ply for further information read the last line of p metzgers signature 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
