METHOD FOR THE SECURE UNINDIRECTIONAL TRANSMISSION OF SIGNALS

• US 20130010954A1
• Filed: 02/14/2011
• Published: 01/10/2013
• Est. Priority Date: 03/11/2010
• Status: Active Grant

• Current Assignee: Siemens Mobility GmbH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Falk, Rainer, Fries, Steffen
• Granted Patent: US 9,628,278 B2
• Time in Patent Office: Days
• US Class Current: 380/255
• CPC Class Codes: H04L 63/0442 wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30
• CPC Class Codes: H04L 63/123 received data contents, e.g. message integrity
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

A method transmits a signal using a unidirectional communications link, which is protected by an asymmetric cryptography method. A counter value is incremented by a transmitter during a transmission operation. Subsequently, a challenge is determined by the transmitter on the basis of the counter value and a control command that can be executed by a receiver and, on the basis of the challenge that is determined a response is in turn determined. The challenge and the response are transmitted from the transmitter to the receiver. The challenge received is then checked by the receiver to see whether the counter value used in the challenge is greater than a counter value previously stored by the transmitting transmitter. The response received is checked on the basis of the challenge. Following successful checking of the challenge and response, the control command transmitted in the challenge is executed.

Claims

1-11. -11. (canceled)

12. A method for transmitting a signal via a unidirectional communications link, protected by an asymmetric cryptography method, comprising:

incrementing, at a transmitter, a counter value, the counter value being incremented based on occurrence of a transmission procedure;

determining, at the transmitter, a challenge based on the counter value and a control command executable by a receiver;

determining, at the transmitter, a response based on the challenge; and

transmitting the challenge and the response, from the transmitter to the receiver.

13. The method as claimed in claim 12, wherein the challenge is repeatedly transmitted to ensure successful reception.

14. The method as claimed in claim 13, wherein

the transmission procedure is transmission of the challenge, and

the counter value is increased with each transmission of the challenge.

15. The method as claimed in claim 13, wherein

the transmission procedure is transmission of the challenge, and

the counter value is incremented with a first transmission of the challenge and then the counter value remains unchanged when the challenge is repeatedly transmitted.

16. The method as claimed in claim 12, wherein for initializing, the receiver stores an item of identification information of the transmitter, and the identification information comprises at least one serial number of the transmitter.

17. The method as claimed in claim 16, wherein the identification information comprises a digital certificate or a public key of the transmitter.

18. The method as claimed in claim 12, wherein

an integrity key is derived at the transmitter on the basis of the response, and

to protect integrity of the challenge, a cryptographic check sum is transmitted with the integrity key via the challenge.

19. A method for checking a signal transmitted, comprising:

receiving at a receiver, a challenge and a response pertaining to the challenge;

checking the challenge to determine whether a counter value used in the challenge is greater than a counter reference value previously stored by receiver;

checking the response on the basis of the challenge; and

after successful checking of the challenge and the response, executing, by the receiver, a control command used in the challenge.

20. The method as claimed in claim 19, further comprising storing the counter value at the receiver after each successful reception of a valid challenge, the counter value being stored as an updated counter reference value.

21. A transmitter device for unidirectional communications using asymmetric cryptography, comprising:

a counter having a counter value incremented based on occurrence of a transmission procedure;

a challenge device to determine a challenge based on the counter value and a control command executable by a receiver;

a response device to determine a response based on the challenge; and

a transmitter to transmit the challenge and the response to the receiver.

22. The transmitter device as claimed in claim 21, wherein a security module provided in the transmitter device securely executes cryptographic operations and protects against technical software attacks, physical attacks and side channel attacks.

23. A receiver device comprising:

a receiver to receive a challenge and a response pertaining to the challenge;

a checking device to;

check the challenge to determine whether a counter value used in the challenge is greater than a counter reference value previously stored by receiver; and

check the response on the basis of the challenge; and

a processor to execute a control command used in the challenge, after successful checking of the challenge and the response.