@Misc{PR92, author = { Pogue, Jr., Russell W. and Ronald L. Rivest }, title = { Method of secure remote access }, howpublished = { U.S. Patent 5,144,667. Issued December 20, 1990. }, date = { 1990-12-20 }, OPTyear = { 1990 }, OPTmonth = { December 20, }, urla = { google-patent-page }, abstract = { Access to a vehicle by a remote electronic key via a radio link is secured by an exchange of encrypted signals. A remote unit having a secret number is introduced to a base unit and a common key is agreed upon by an exponential key exchange. The common key is encrypted using the secret number and stored in the base unit. Thereafter, the base unit is able to authenticate the identity of the remote unit by sending the encrypted common key and a random number to the remote unit which decrypts the key and uses it to encrypt the random number. The random number is also encrypted in the base unit and compared with the encrypted random number from the remote unit. }, }