re how to detect use of an illegal cipher in article betel camelot betel camelot bradley edu robert crawford writes jay fenton fenton kaleida com writes how can the government tell which encryption method one is using without being able to decode the traffic i e in order to accuse me of using an unauthorized strong encryption technique they would have to take both keys out of escrow run them against my ciphertext and draw a blank i was thinking about this also it s quite possible the system transmits in clear the serial number of the device being used that way they can start a tap get the serial number and use the warrant for the first tap to get the key if they tap someone who s apparently using encryption but don t find that prefix then they ll assume it s an un authorized encryption scheme 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 bill smythe
