Privacy and authentication on a portable communications system

Public-key/private-key hybrid key agreements and authentication protocols which maintain privacy of conversation and location information, and deter usage fraud, are presented. These protocols are optimized for low complexity in the portable unit and network infrastructure. The basic cryptographic techniques are described, and some complexity information obtained from these laboratory experiments and from other sources are presented. The three public-key protocols described have differing levels of security and complexity: and the tradeoffs are discussed. Because of the complexity concerns mentioned above, the public-key protocols are compared to a representative private-key approach in the areas of both security and computational complexity