Authentication of a vehicle-external device

• US 20070067635A1
• Filed: 10/27/2006
• Published: 03/22/2007
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Kuhls, Burkhard, Kiessling, Horst
• Granted Patent: US 8,886,943 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: B60R 25/00 Fittings or systems for preventing or indicating unauthorised use or theft of vehicles locks for vehicles E05B77/00-E05B85/00
• CPC Class Codes: B60R 25/04 operating on the propulsion system, e.g. engine or drive motor
• CPC Class Codes: H04L 2209/84 Vehicles
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A method for authenticating a vehicle-external device in a bus system of a motor vehicle comprising control units is provided. In order to effectively and inexpensively prevent a sequence control system that is stored in a control unit from being manipulated, an authentication device is provided in the bus system. The authentication device transmits an authentication request to the vehicle-external device. The vehicle-external device signs the authentication request with a secret key of an asymmetric pair of keys, such as a pair of public keys, and transmits the signed authentication request or exclusively the signature to the authentication device. The authentication device determines a signature of the authentication request using the same algorithm as the vehicle-external device, and decodes the signature transmitted by the vehicle-external device using the public key which is complementary to the secret key, and compares the determined signature with the transmitted signature.

Claims

1. A method for authenticating a vehicle-external device in a bus system of a motor vehicle comprising control units, the bus system including an authentication device, the method comprising the acts of:

transmitting, by the authentication device, an authentication request to the vehicle-external device;

signing, by the vehicle-external device, the authentication request with a secret key of an asymmetric pair of keys;

transmitting, by the vehicle-external device, the signed authentication request or only the signature to the authentication device;

determining, by the authentication device, a signature of the authentication request using a same algorithm as the vehicle-external device;

decoding the signature transmitted by the vehicle-external device using the public key, which is complementary to the secret key; and

comparing the determined signature with the transmitted signature.

2. The method of claim 1, wherein when the determined signature and the transmitted signature results in a positive comparison or match, the vehicle-external device obtains write and/or read access to a store of at least one of the control units by way of the authentication device.

3. The method of claim 1, wherein

a first control unit transmits an authentication request to the authentication device for authenticating the control units,

the authentication device signs the authentication request using a first symmetric key and transmits the signed authentication request or only the signature to the first control unit,

wherein

the first control unit compares the transmitted signature of the authentication request with a signature, which is determined by the first control unit by applying the symmetric key to the authentication request;

or

the first control unit decodes the transmitted signature of the authentication request using the first symmetric key, and a first hash value is obtained, and the first control unit applies a hash algorithm to the authentication request, whereby a second hash value is obtained; and

the first control unit is rendered operational if the comparison of the signatures and/or the hash values is positive and/or if the signatures and/or the hash values match.

4. The method of claim 3, wherein one or more of the other control units of the bus system carries out the method for authentication.

5. The method of claim 3, wherein the motor vehicle may be started up only after all of the control units of the bus system have executed to the method for authentication with positive results from the comparison.

6. The method of claim 1 wherein the execution of the authentication method is carried out prior to starting the vehicle.

7. The method of claim 3, wherein all control units use the same symmetric key in carrying out the authentication method.

8. The method of claim 3, wherein the symmetric key varies from vehicle to vehicle, and in carrying out the method a control unit of a first vehicle uses a first symmetric key and the same control unit of a second vehicle uses a second symmetric key.

9. The method of claim 1, wherein the asymmetric pair of keys are a pair of public keys

10. A method for authenticating a vehicle-external device in a bus system of a motor vehicle comprising control units, the bus system including an authentication device, the method comprising the acts of:

transmitting, by the authentication device, an authentication request to the first control unit;

signing, by the first control unit, the authentication request with the first symmetric key;

transmitting the signed authentication request or only the signature to the authentication device;

determining, by the vehicle-external device, a signature of the authentication request using a same algorithm as the first control unit;

decoding the signature transmitted by the first control unit using the public key, which is complementary to the secret key; and

comparing the determined signature with the transmitted signature.

11. A bus system of a motor vehicle, comprising:

control units;

an authentication device; and

a vehicle-external device,

wherein

the authentication device transmits an authentication request to the vehicle-external device,

the vehicle-external device signs the authentication request with a secret key of an asymmetric pair of keys;

the vehicle-external device transmits the signed authentication request or only the signature to the authentication device,

the authentication device determines a signature of the authentication request using a same algorithm as the vehicle-external device,

the signature transmitted by the vehicle-external device is decoded using the public key, which is complementary to the secret key, and

the determined signature is compared with the transmitted signature.

12. A bus system of a motor vehicle, comprising:

control units;

an authentication device; and

a vehicle-external device,

wherein the authentication device and vehicle-external device include computer program products for performing the acts of

transmitting, by the authentication device, an authentication request to the vehicle-external device;

signing, by the vehicle-external device, the authentication request with a secret key of an asymmetric pair of keys;

transmitting, by the vehicle-external device, the signed authentication request or only the signature to the authentication device;

determining, by the authentication device, a signature of the authentication request using a same algorithm as the vehicle-external device;

decoding the signature transmitted by the vehicle-external device using the public key, which is complementary to the secret key; and

comparing the determined signature with the transmitted signature.