Computational System

• US 20150095660A1
• Filed: 09/30/2013
• Published: 04/02/2015
• Est. Priority Date: 09/30/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Gammel, Berndt, Felicijan, Tomaz, Mangard, Stefan
• Granted Patent: US 9,195,857 B2
• Time in Patent Office: Days
• US Class Current: 713/192
• CPC Class Codes: G06F 21/445 by mutual authentication, e.g. between devices or programs
• CPC Class Codes: G06F 21/71 to assure secure computing or processing of information
• CPC Class Codes: G06F 21/72 in cryptographic circuits
• CPC Class Codes: G06F 2221/2103 Challenge-response
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: H04L 9/004 for fault attacks

Abstract

A computational system is configured to protect against integrity violation. The computational system includes a processing unit and a critical resource, the critical resource being controllable by the processing unit so as to be locked or unlocked. The critical resource is configured to intermittently transmit a polling value to the processing unit, and the processing unit is configured to apply a transformation onto the polling value so as to obtain a response value and send the response value back to the critical resource. The critical resource is configured to check the response value on correctness so as to obtain a check result, and subject the controllability to a dependency on the check result.

Claims

1. A computational system configured to protect against integrity violation, the computational system comprising a processing unit and a critical resource, the critical resource being controllable by the processing unit so as to be locked or unlocked,

wherein the critical resource is configured to intermittently transmit a polling value to the processing unit, the processing unit being configured to apply a transformation onto the polling value so as to obtain a response value and send the response value back to the critical resource, and the critical resource being configured to check the response value on correctness so as to obtain a check result, and subject the controllability to a dependency on the check result.

2. The computational system according to claim 1, wherein the critical resource is configured to initiate the transmission of the polling value to the critical resource upon receipt of a command from the processing unit controlling the critical resource so as to unlock.

3. The computational system according to claim 1, wherein the critical resource is configured to subject the controllability to a dependency on the check result of the response value of a sequence of polling values.

4. The computational system according to claim 1, wherein the critical resource is configured to subject the controllability to a dependency on the check result of the response value of a sequence of polling values, wherein the critical resource comprises a plurality of registers and is configured to read the sequence of polling values from different ones of the plurality of registers.

5. The computational system according to claim 1, wherein the critical resource comprises a register, the critical resource being configured to read the polling value from the register and write back the response value to the register so as to serve as polling value for a next transmission to the processing unit.

6. The computational system according to claim 5, wherein the critical resource is configured to subject the controllability to a dependency on the check result of the response value of a sequence of polling values.

7. The computational system according to claim 5, wherein the critical resource is configured to intermittently change a storage content of the register.

8. The computational system according to claim 5, wherein the critical resource is configured to intermittently change a storage content of the register using a random or pseudo-random sequence of values.

9. The computational system according to claim 1, wherein the processing unit is configured to sequentially change the transformation in a deterministically manner.

10. The computational system according to claim 1, wherein the critical resource is configured to, in subjecting the controllability to a dependency on the check result, count a number of accesses of the processing unit to the critical resource during the critical resource being unlocked, so as to automatically lock upon the number of accesses exceeding a predetermined value.

11. The computational system according to claim 1, wherein the critical resource is configured to, in subjecting the controllability to a dependency on the check result, measure a time duration of the critical resource being unlocked, so as to automatically lock upon the time duration exceeding a predetermined value.

12. The computational system according to claim 1, wherein the processing unit is configured to control the critical resource so as to be locked in case of the critical resource being not required for an operation of the computational system, and unlocked in case of the critical resource being required for the operation of the computational system.

13. A method for protecting a computational system against integrity violation, the computational system comprising a processing unit and a critical resource, the critical resource being controllable by the processing unit so as to be locked or unlocked, wherein the method comprises:

intermittently transmitting a polling value from the critical resource to the processing unit;

applying a transformation onto the polling value so as to obtain a response value;

sending the response value from the processing unit back to the critical resource;

checking the response value on correctness so as to obtain a check result; and

subjecting the controllability of the critical resource to a dependency on the check result.

14. The method according to claim 13, comprising:

initiating the transmission of the polling value to the critical resource upon receipt of a command from the processing unit controlling the critical resource so as to unlock.

15. The method according to claim 13, comprising:

subjecting the controllability to a dependency on the check result of the response value of a sequence of polling values.

16. The method according to claim 13, wherein the critical resource comprises a plurality of registers, wherein the method comprises:

subjecting the controllability to a dependency on the check result of the response value of a sequence of polling values; and

reading the sequence of polling values from different ones of the plurality of registers.

17. The method according to claim 13, wherein the critical resource comprises a register, wherein the method comprises:

reading the polling value from the register and writing back the response value to the register so as to serve as polling value for a next transmission to the processing unit.

18. The method according to claim 13, comprising:

subjecting the controllability to a dependency on the check result of the response value of a sequence of polling values.

19. The method according to claim 13, wherein subjecting the controllability to a dependency on the check result comprises counting a number of accesses of the processing unit to the critical resource during the critical resource being unlocked, so as to automatically lock upon the number of accesses exceeding a predetermined value.

20. The method according to claim 13, wherein subjecting the controllability to a dependency on the check result comprises measuring a time duration of the critical resource being unlocked, so as to automatically lock upon the time duration exceeding a predetermined value.

21. A non-transitory computer-readable storage medium storing program instructions which when executed by a computational system protects the computational system against integrity violation, the computational system comprising a processing unit and a critical resource, the critical resource being controllable by the processing unit so as to be locked or unlocked,

the program instructions comprising:

first program code for causing the computational system to execute processing of intermittently transmitting a polling value from the critical resource to the processing unit;

second program code for causing the computational system to execute processing of applying a transformation onto the polling value so as to obtain a response value;

third program code for causing the computational system to execute processing of sending the response value from the processing unit back to the critical resource;

forth program code for causing the computational system to execute processing of checking the response value on correctness so as to obtain a check result; and

fifth program code for causing the computational system to execute processing of subjecting the controllability of the critical resource to a dependency on the check result.

22. An integrated chip comprising a central processing unit and a cryptographic peripheral, the cryptographic peripheral being controllable by the central processing unit so as to be locked or unlocked,

wherein the cryptographic peripheral is configured to intermittently transmit a polling value to the central processing unit, the central processing unit being configured to apply a transformation onto the polling value so as to obtain a response value and send the response value back to the cryptographic peripheral, and the cryptographic peripheral being configured to check the response value on correctness so as to obtain a check result, and subject the controllability to a dependency on the check result,

wherein the central processing unit is configured to control the cryptographic peripheral so as to be locked if the cryptographic peripheral is not required by a program executed on the central processing unit, and unlocked if the cryptographic peripheral is required by the program executed on the central processing unit.