Exponent splitting for cryptographic operations

Patent metadata

Field	Value
Publication number	US-11032060-B2
Application number	US-201916534719-A
Country	US
Kind code	B2
Filing date	Aug 7, 2019
Priority date	Oct 3, 2014
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A first share value and a second share value may be received. A combination of the first share value and the second share value may correspond to an exponent value. The value of a first register is updated using a first equation that is based on the first and second share values and the value of a second register is updated using a second equation that is based on the second share value. One of the value of the first register or the value of the second register is selected based on a bit value of the second share value.

First claim

What is claimed is:

1. A method comprising:
receiving a first share value and a second share value, wherein a combination of the first share value and the second share value corresponds to a value associated with a cryptographic operation;
updating a first value of a first register by performing a first operation with the first and second share values as inputs to the first operation;
updating a second value of a second register by performing a second operation with the second share value as an input to the second operation;
selecting, by a processing device, one of the first value of the first register or the second value of the second register based on a particular bit of the second share value; and
performing the cryptographic operation with the selected one of the first value of the first register or the second value of the second register.

2. The method of claim 1 , wherein the particular bit corresponds to a least significant bit of the second share value.

3. The method of claim 1 , wherein the particular bit corresponds to a most significant bit of the second share value.

4. The method of claim 1 , wherein the cryptographic operation corresponds to a generation of a signature.

5. The method of claim 1 , wherein the value associated with the cryptographic operation corresponds to an exponent value used in the cryptographic operation.

6. The method of claim 1 , wherein the first operation and the second operation are each associated with power consumption to reduce susceptibility to a Differential Power Analysis (DPA) attack.

7. The method of claim 1 , wherein the first value of the first register is selected to be used in the cryptographic operation responsive to the particular bit value of the second share value being at a first value and the second value of the second register is selected to be used in the cryptographic operation responsive to the particular bit value of the second share value being at a second value that is different than the first value.

8. A system comprising:
a memory; and
a processing device, operatively coupled with the memory, to:
receive a first share value and a second share value, wherein a combination of the first share value and the second share value corresponds to a value associated with a cryptographic operation;
update a first value of a first register by performing a first operation with the first and second share values as inputs to the first operation;
update a second value of a second register by performing a second operation with the second share value as an input to the second operation;
select one of the first value of the first register or the second value of the second register based on a particular bit of the second share value; and
perform the cryptographic operation with the selected one of the first value of the first register or the second value of the second register.

9. The system of claim 8 , wherein the particular bit corresponds to a least significant bit of the second share value.

10. The system of claim 8 , wherein the particular bit corresponds to a most significant bit of the second share value.

11. The system of claim 8 , wherein the cryptographic operation corresponds to a generation of a signature.

12. The system of claim 8 , wherein the value associated with the cryptographic operation corresponds to an exponent value used in the cryptographic operation.

13. The system of claim 8 , wherein the first operation and the second operation are each associated with power consumption to reduce susceptibility to a Differential Power Analysis (DPA) attack.

14. The system of claim 8 , wherein the first value of the first register is selected to be used in the cryptographic operation responsive to the particular bit value of the second share value being at a first value and the second value of the second register is selected to be used in the cryptographic operation responsive to the particular bit value of the second share value being at a second value that is different than the first value.

15. A non-transitory computer readable medium comprising instructions, which when executed by a processing device, cause the processing device to perform operations comprising:
receiving a first share value and a second share value, wherein a combination of the first share value and the second share value corresponds to a value associated with a cryptographic operation;
updating a first value of a first register by performing a first operation with the first and second share values as inputs to the first operation;
updating a second value of a second register by performing a second operation with the second share value as an input to the second operation;
selecting one of the first value of the first register or the second value of the second register based on a particular bit of the second share value; and
performing the cryptographic operation with the selected one of the first value of the first register or the second value of the second register.

16. The non-transitory computer readable medium of claim 15 , wherein the particular bit corresponds to a least significant bit of the second share value.

17. The non-transitory computer readable medium of claim 15 , wherein the particular bit corresponds to a most significant bit of the second share value.

18. The non-transitory computer readable medium of claim 15 , wherein the cryptographic operation corresponds to a generation of a signature.

19. The non-transitory computer readable medium of claim 15 , wherein the first value of the first register is selected to be used in the cryptographic operation responsive to the particular bit value of the second share value being at a first value and the second value of the second register is selected to be used in the cryptographic operation responsive to the particular bit value of the second share value being at a second value that is different than the first value.

20. The non-transitory computer readable medium of claim 15 , wherein the value associated with the cryptographic operation corresponds to an exponent value used in the cryptographic operation.

Assignees

• Cryptography Res Inc

Inventors

• Tunstall Michael

Classifications

• G06F2207/7242

  Exponent masking, i.e. key masking, e.g. A**(e+r) mod n; (k+r).P · CPC title

• H04L9/003 Primary

  for power analysis, e.g. differential power analysis [DPA] or simple power analysis [SPA] · CPC title

• G06F21/755

  with measures against power attack · CPC title

• G06F7/723

  Modular exponentiation (G06F7/724, G06F7/727, G06F7/728 take precedence) · CPC title