Derivation of a Device-Specific Value

• US 20150318999A1
• Filed: 04/30/2015
• Published: 11/05/2015
• Est. Priority Date: 04/30/2014
• Status: Abandoned Application

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Falk, Rainer, Mucha, Andreas
• Application Number:
  US14/700,430
• Publication Number:
  US 20150318999A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 21/44 Program or device authentication
• CPC Class Codes: H04L 63/0876 based on the identity of the terminal or configuration, e.g. MAC address, hardware or software configuration or device fingerprint
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords
• CPC Class Codes: H04L 9/0866 involving user or device identifiers, e.g. serial number, physical or biometrical information, DNA, hand-signature or measurable physical characteristics
• CPC Class Codes: H04L 9/3278 using physically unclonable functions [PUF]

Abstract

A method and an apparatus for deriving a device-specific value from a physical unclonable function realized on a circuit unit are provided. Response values from a physical unclonable function (PUF) are categorized with respect to a statistical property, such as a bit error characteristic, and the device-specific value is derived therefrom.

Claims

1. A method for deriving a device-specific value from a physical unclonable function realized on a circuit unit, the method comprising:

applying an identical challenge to the physical unclonable function of the circuit unit at least twice in order to produce at least two responses;

deriving, by a processor, a categorization information item associated with the identical challenge from a statistical property of the at least two responses; and

producing the device-specific value from the categorization information item.

2. The method of claim 1, further comprising ascertaining a bit error characteristic from a series of responses as a categorization information item.

3. The method of claim 2, further comprising:

deriving an association with one of at least two categories that are derivable by at least one threshold value from the categorization information item; and

producing the device-specific value from the association with the one category.

4. The method of claim 3, wherein the device-specific value indicates the association with the one category as a binary value.

5. The method of claim 1, wherein the categorization information item is ascertained by comparing at least one response of the at least two responses with a reference response, and the device-specific value is produced therefrom.

6. The method of claim 1, wherein the device-specific value is used as an integrity identifier for a device.

7. The method of claim 1, further comprising forming a key bit of a cryptographic key from the device-specific value.

8. A method for deriving a series of device-specific values, the method comprising:

deriving device-specific values with a plurality of challenges from a physical unclonable function realized on a circuit unit, the deriving for each challenge of the plurality of challenges comprising;

applying the challenge to the physical unclonable function at least twice in order to produce at least two responses;

deriving, by a processor, a categorization information item associated with the challenge from a statistical property of the at least two responses; and

producing the device-specific value from the categorization information item; and

producing the series of device-specific values from the respective device-specific values.

9. The method of claim 8, wherein a cryptographic key is formed from the series of device-specific values.

10. The method of claim 8, wherein the deriving for each challenge of the plurality of challenges further comprises ascertaining a bit error characteristic from a series of responses as a categorization information item.

11. The method of claim 10, wherein the deriving for each challenge of the plurality of challenges further comprises:

deriving an association with one of at least two categories that are derivable by at least one threshold value from the categorization information item; and

producing the device-specific value from the association with the one category.

12. The method of claim 11, wherein the device-specific value indicates the association with the one category as a binary value.

13. The method of claim 8, wherein the categorization information item is ascertained by comparing at least one response of the at least two responses with a reference response, and the device-specific value is produced therefrom.

14. The method of claim 8, wherein the device-specific value is used as an integrity identifier for a device.

15. The method of claim 8, wherein the deriving for each challenge of the plurality of challenges further comprises forming a key bit of a cryptographic key from the device-specific value.

16. An apparatus comprising:

a challenge generator configured to produce at least one challenge;

a circuit unit comprising at least one physical unclonable function for deriving at least one device-specific value, the circuit unit being configured to produce at least two responses when the at least one physical unclonable function has an identical challenge of the at least one challenge applied to the at least one physical unclonable function at least twice;

a response categorizer configured to derive a categorization information item from a statistical property of the at least two responses; and

a derivation unit configured to derive the device-specific value from the categorization information item.

17. The apparatus of claim 16, further comprising:

a key formation unit configured to produce a cryptographic key from a series of device-specific values produced based on the derived device-specific value;

a key memory configured to store the cryptographic key.