re clipper two additional possible problems begin pgp signed message in article cliftonrc tvt al netcom com cliftonr netcom com pope clifton writes if i want to talk to someone i don t need to have previously exchanged keys with him i just call him up and the phones establish a session key for us using a zero knowledge algorithm or something of the kind if i ve misunderstood this part it probably invalidates the rest of this notion this lends itself to spoofing i go buy a pair of clipper phones to go on a pair of phone lines in a back room somewhere and have the digital switch programmed to redirect his calls to one of my two lines instead of to his whenever he receives a call the two phones are wired back to back in the clear anyone see any problem with this scheme other than to assume that all public officials and phone company employees are totally incorruptible as far as i can see no matter how the session keys are generated be it diffie hellman or whatever any cripple conversation which travels in whole or in part over a land line is vulnerable to this scheme law enforcement agencies can do it legally at the telco or illegally by finding some part of the phone line that they can cut into the degree of risk depends very much on location not good in the middle of a busy street but not bad on a line in open country leading to a drug lord s ranch the only way to defeat it would be if your phone had the equivalent of a public key indexed against phone number for every phone you might want to call all of them totally impractical even if some part of the cripple algorithm could be used as a kind of public key i don t understand enough about these things to know this sort of encryption scheme is only really workable over a radio link and even then you could probably interevene without causing problems for other phones nearby if you were physically close to the target phone gosh yet another way to get round cripple encryption how many is that we ve found so far and that s without even knowing the details of the algorithm paul
