At the time when digital cellular was first designed, the main objective was to design sufficiently strong authentication to stem the rampant theft of service t

At the time when digital cellular was first designed, the main objective was to design sufficiently strong authentication to stem the rampant theft of service then occurring on the analog cellular systems. In the US this was estimated at roughly $2 billion/annum. Encrypting traffic for privacy purposes was less important. Prior analog cellular telephony systems were unencrypted, as were analog and digital wireline services. Thus, the privacy cryptography was intended to be strong enough to make it a little more inconvenient/expensive to eavesdrop on digital cellular than it was on analog cellular or wireline services without significantly impeding law enforcement.