a passive keyless system including a base that selectively allows access to a restricted environment through a base transceiver operating with an encrypted link on first and second frequencies , and a base recording element storing base measured movement history information . also , a passive keyless device with at least one sensor detects a movement property of the device , a device recording element stores movement history information about the device and reflecting the detected movement property , and a device transceiver communicating with the base transceiver , and transmitting to the base transceiver encrypted security information identifying the device in accordance with a passive keyless protocol and / or the movement history information , and an access request element that causes the device transceiver to request access to the base transceiver . the base uses the base measured movement history information and movement history information when allowing access to the restricted environment .