A first device includes: a first reference signal source; a first transmitting/receiving unit which transmits two or more first carrier signals and receives two or more second carrier signals using an output of the first reference signal source; and a calculating unit. A second device includes: a second reference signal source configured to be operated independently from the first reference signal source; and a second transmitting/receiving unit configured to transmit two or more second carrier signals and receive two or more first carrier signals using an output of the second reference signal source. A frequency group of two or more first carrier signals and a frequency group of two or more second carrier signals differ from each other. The calculating unit calculates a distance between the first device and the second device based on a phase detection result obtained by receiving the first and second carrier signals.

A security system includes a portable terminal, a communication device communicating with the portable terminal, and a determination unit determining validity of the portable terminal. Phase data acquired from distance measuring radio wave is used to determine validity of communication between the portable terminal and the communication device. The received phase data of the distance measuring radio wave varies according to the distance from a transmission source. When the communication device and the portable terminal are fixed, and the communication device and the portable terminal have transmitted and received distance measuring radio waves having the same specific frequency, vehicle acquisition phase data and terminal acquisition phase data are the same. The determination unit determines, by using this two types of phase data, the validity of communication between the communication device and the portable terminal is determined.

There is provided a method and a system for authorizing a user device to send a request to a vehicle in order to prevent a physical layer relay attack. The system comprises a vehicle comprising an acoustic transducer and an RF transceiver and a user device comprising an acoustic transducer and an RF transceiver. The method relates to a signaling scheme using a combination of acoustic and RF signals for preventing a successful physical layer relay attack.

A method and system for detecting if a relay is present in a PEPS system for a vehicle is provided which includes (a) transmitting LF signals from antennas associated with a vehicle to a key fob using a 3D LF receiver to measure the LF signal level on the x, y and z-axes; (b) selecting two or more parallel antennas associated with the vehicle that are orthogonal to the antenna at the PEPS triggering location; (c) normalizing the x, y and z vectors that are measured by the key fob for the selected two or more parallel antennas associated with the vehicle; and (d) determining if the normalized x, y and z vectors for the selected two or more parallel antennas associated with the vehicle are within a predefined range.

According to certain examples, a circuit-based wireless communications system provides secure access to a vehicle by way of certain circuitry configure to compare a first RF background observed for a vehicle-located RF receiver that is part of a vehicle-located circuit secured to a vehicle, with a second RF background observed for a wireless-communications vehicle-access circuit that includes another RF receiver. In response, a distance metric is generated to indicate a degree of similarity between the first RF background and the second RF background, and based on whether this metric satisfies a threshold, access to the vehicle may be granted via the wireless-communications vehicle-access circuit.

According to an embodiment, a first device includes: a first transceiver configured to transmit two or more first carrier signals using an output of a first reference signal source and to receive two or more second carrier signals; and a calculation unit, and a second device includes: a second transceiver configured to transmit the two or more second carrier signals using an output of a second reference signal source that operates independently of the first reference signal source and to receive the two or more first carrier signals. A frequency group of the two or more first carrier signals and a frequency group of the two or more second carrier signals are identical or substantially identical to each other, and the calculation unit calculates the distance between the first device and the second device based on a phase detection result obtained by receiving the first and second carrier signals.

There is provided a method and a system for authorizing a user device to send a request to a vehicle in order to prevent a physical layer relay attack. The system comprises a vehicle comprising an acoustic transducer and an RF transceiver and a user device comprising an acoustic transducer and an RF transceiver. The method relates to a signaling scheme using a combination of acoustic and RF signals for preventing a successful physical layer relay attack.

A method for a receiver locates an authentication unit of a motor vehicle. The method includes determining environment information relating to the receiver. The method also includes receiving a reception signal from a transmitter. The method further includes determining a relative position of the transmitter with respect to the receiver on the basis of the environment information and the reception signal.

A method of transmitting signals from a first node having multiple transceivers to a second node is disclosed. The method comprises receiving a message from the second node at the first node, wherein the message is received by each of a plurality of transceivers of the first node; and transmitting by each of the plurality of transceivers a respective data frame to the second node in response to the message; wherein each transceiver initiates the transmission of its respective data frame a predetermined time period after receipt of the message by the transceiver; and wherein the transmissions of the data frames from the plurality of transceivers overlap. The data frames may form part of a two-way ranging exchange.

System and techniques for a secure wireless lock-actuation exchange are described herein. After receiving a request to actuate a lock from a device, a controller can calculate a challenge counter and then perform verification iterations until an end condition is met—which is a failure of a verification iterations or the number of iterations reaches the challenge count. If the verification iterations reach the challenge count (e.g., there are no failed iterations), then the controller actuates the lock. Each iteration includes an exchange between the device and the controller that the device validates by signing a message with a private key shared by the device and the controller. The exchange also includes a freshness value integrated into the device validation to prevent replay attacks.