Method for the encrypted radio transmission of data

• US 9,724,972 B2
• Filed: 05/23/2013
• Issued: 08/08/2017
• Est. Priority Date: 12/06/2010
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Zucchetti, Cristian, Schwab, Axel
• Primary Examiner(s): Homayounmehr, Farid
• Assistant Examiner(s): Le, Thanh T
• Application Number:
  US13/900,695
• Publication Number:
  US 20130322629A1
• Time in Patent Office: 1,538 Days
• Field of Search: None
• CPC Class Codes: B60C 23/0447 Wheel or tyre mounted circuits
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/00 Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
• CPC Class Codes: H04L 9/08 Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords network architectures or network communication protocols for supporting key management in a packet data network H04L63/06

Abstract

A method is provided for encrypted radio transmission of data telegrams spaced apart in time in a sequence between a transmitter and a receiver of a system, wherein a key is changeable and is cryptologically derived from a current piece of information. The time elapsed between a preceding telegram and the encrypted telegram implementing the desired data transmission is used as the key. The time span results from a value or entry of a parameter present in the system. The duration in the transmitter and the receiver is determinable from a previously transmitted value or entry of a parameter, or derived only in the transmitter and wirelessly transmitted to the receiver for a future telegram. In a motor vehicle tire pressure monitoring system, the transmitted data originate from a tire sensor and are wirelessly transmitted in an encrypted manner to a vehicle body.

Claims

1. A method for encrypted radio transmission of data between a transmitter and a receiver of a tire pressure control system, wherein data to be transmitted originates from a sensor provided in a vehicle tire wirelessly transmitted in an encrypted manner to the receiver provided at a vehicle body, the method comprising the acts of:

transmitting encrypted short telegrams mutually spaced apart in time, wherein an encryption key is changeable;

setting a time period between a preceding telegram transmission and a scheduled transmission of a current telegram to be transmitted in the future, wherein the time period is set based on a value or an amount of a parameter present in the system;

using the time period as the encryption key for encrypting said current telegram to be transmitted; and

transmitting the data from the transmitter to the receiver via the encrypted current telegram.

2. The method according to claim 1, wherein the value or the amount of one of the following parameters or a quantity derived therefrom is used for defining the time period:

a pressure in the vehicle tire determined by the sensor,

a temperature in the vehicle tire determined by the sensor,

a rotational speed of the vehicle tire,

a rotating direction of the vehicle tire,

a vertical tire force on a roadway,

a residual service life of a battery provided in the vehicle tire,

an identification number of the sensor, and

a time period used as a key in a preceding transmission.

3. The method according to claim 1, wherein the time period in the transmitter and in the receiver is set from a preceding transmitted value or amount of a parameter by each of the respective transmitter and receiver.

4. The method according to claim 2, wherein the time period in the transmitter and in the receiver is set from a preceding transmitted value or amount of a parameter by each of the respective transmitter and receiver.

5. The method according to claim 1, wherein the time period is set only in the transmitter and is wirelessly transmitted to the receiver for the current telegram prior to the transmission of the current telegram.

6. The method according to claim 2, wherein the time period is set only in the transmitter and is wirelessly transmitted to the receiver for the current telegram prior to the transmission of the current telegram.

7. The method according to claim 1, wherein the preceding telegram is transmitted essentially only for defining a beginning of the time period for the current telegram implementing the desired data transmission.

8. The method according to claim 2, wherein the preceding telegram is transmitted essentially only for defining a beginning of the time period for the current telegram implementing the desired data transmission.

9. The method according to claim 2, wherein the setting of the time period is carried out such that:

as a function of the vehicle tire pressure, a shorter time period is obtained when, viewed over successive telegrams, a change of pressure is relatively large, whereas a greater time period is obtained when, viewed over successive telegrams, virtually no change of pressure is determinable, and

as a function of the rotational speed of the vehicle tire at a higher speed, a shorter time period is obtained than at a lower speed.

10. The method according to claim 1, wherein misinformation received by the receiver in a time window not corresponding to the set time period used as the encryption key is registered and stored as misinformation.

11. The method according to claim 1, further comprising:

an scheduled transmission time, corresponding to a time at which the current telegram is scheduled to be transmitted in the future, based on a cryptological function and on the value or amount of the parameter present in the system,

wherein the time period is set based on a difference between the scheduled transmission time and the preceding telegram transmission.

12. The method according to claim 11, further comprising:

transmitting the current telegram at the scheduled transmission time.

13. A method for encrypted radio transmission of data between a transmitter and a receiver of a tire pressure control system, wherein data to be transmitted originates from a sensor provided in a vehicle tire wirelessly transmitted in an encrypted manner to the receiver provided at a vehicle body, the method comprising the acts of:

transmitting encrypted short telegrams mutually spaced apart in time, wherein an encryption key is changeable;

setting an scheduled transmission time corresponding to a time at which a current telegram is scheduled to be transmitted in the future based on a cryptological function and on the value or amount of the parameter present in the system;

calculating a time period based on a difference between the scheduled transmission time and the preceding telegram transmission, wherein the time period is defined by a difference between the scheduled transmission time and the preceding telegram transmission;

using the calculated time period as the encryption key for encrypting said current telegram to be transmitted for transmitting the data from the transmitter to the receiver; and

transmitting the current encrypted telegram at the scheduled transmission time.