Device for generating at least one cryptographic key, corresponding methods and computer program products

Patent metadata

Field	Value
Publication number	US-12574228-B2
Application number	US-202118044603-A
Country	US
Kind code	B2
Filing date	Sep 10, 2021
Priority date	Sep 10, 2020
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

Abstract

A device for generating at least one cryptographic key by selecting at least three input data selected among, on one hand, a predetermined data and, on the other hand, a function of at least one piece of data having a type belonging to the group including: a physical unclonable type, corresponding to physical unclonable function data, a hardwired type, corresponding to data hardwired within said device, and a software type, corresponding to software data, assembling the at least three input data to produce an assembled input data, and applying the assembled input data into a cryptographic element to produce a cryptographic key.

First claim

The invention claimed is:

1 . A device for generating at least one cryptographic key, said device including at least one cryptographic element, the device comprising:
circuitry configured to implement at least one generation of a cryptographic key comprising:
selecting at least three input data, each of said at least three input data being selected among predetermined data and a function of at least one piece of data having a type belonging to a group comprising:
a physical unclonable type, corresponding to physical unclonable function data;
a hardwired type, corresponding to data hardwired within said device; and
a software type, corresponding to software data, the predetermined data having a same size as the physical unclonable function data, the data hardwired within said device, and the software data;

after selecting said at least three input data, assembling said at least three input data to produce an assembled input data, a size of the assembled input data being constant regardless of whether the predetermined data is selected; and
applying the assembled input data into a cryptographic element to produce said cryptographic key.

2 . The device according to claim 1 , wherein the circuitry is configured to implement three of said generation of a cryptographic key implemented successively for producing a sequence of three cryptographic keys, at least one cryptographic key of given rank in said sequence being a function at least of an input data selected among given predetermined data and a cryptographic key of a previous rank in said sequence.

3 . The device according to claim 1 , wherein the circuitry is configured to implement a first generation of a first cryptographic key comprising selecting at least three first input data being:
a first predetermined data or a first data of physical unclonable type; a second predetermined data or a second data of said hardwired type; and a third predetermined data or a third data of said software type.

4 . The device according to claim 3 , wherein the circuitry is configured to implement a second generation of a second cryptographic key comprising selecting at least three second input data being:
a fourth predetermined data or a fourth data of said physical unclonable type; a fifth predetermined data or said first cryptographic key; and a sixth predetermined data or a fifth data of said software type, wherein assembling said at least three second input data produces an assembled second input data, and wherein applying the assembled second input data into a second cryptographic element produces said second cryptographic key.

5 . The device according to claim 4 , wherein the circuitry is configured to implement a third generation of a third cryptographic key comprising selecting at least three third input data being:
a seventh predetermined data or a sixth data of said physical unclonable type; an eighth predetermined data or said second cryptographic key; and a nineth predetermined data or a seventh data of said software type, wherein assembling said at least three third input data produces an assembled third input data, and wherein applying the assembled third input data into a third cryptographic element produces said third cryptographic key.

6 . The device according to claim 5 , wherein said first data, said fourth data and said sixth data are a same public data of said physical unclonable type.

7 . The device according to claim 6 , wherein said first generation of a first cryptographic key comprises selecting five first input data being said three first input data and:
a tenth predetermined data or a private data of said physical unclonable type; and an eleventh predetermined data or a private data of said hardwired type, wherein assembling said five first input data produces said assembled first input data.

8 . The device according to claim 7 , wherein said fifth data of said software type is different from said software data of said software type.

9 . The device according to claim 1 , wherein said cryptographic element implements a one-way function to produce said cryptographic key based on said input data.

10 . A method for generating at least one cryptographic key by a device including at least one cryptographic element, the method comprising:
implementing, by circuitry of the device, at least one generation of a cryptographic key comprising:
selecting at least three input data, each of the at least three input data being selected among predetermined data and a function of at least one piece of data having a type belonging to a group comprising:
a physical unclonable type, corresponding to physical unclonable function data;
a hardwired type, corresponding to data hardwired within the device; and
a software type, corresponding to software data, the predetermined data having a same size as the physical unclonable function data, the data hardwired within the device, and the software data;

after selecting the at least three input data, assembling the at least three input data to produce an assembled input data, a size of the assembled input data being constant regardless of whether the predetermined data is selected; and
applying the assembled input data into a cryptographic element to produce the cryptographic key.

11 . The method according to claim 10 , wherein the implementing implements three of the generation of a cryptographic key implemented successively for producing a sequence of three cryptographic keys, at least one cryptographic key of given rank in the sequence being a function at least of an input data selected among given predetermined data and a cryptographic key of a previous rank in the sequence.

12 . The method according to claim 10 , wherein the implementing implements a first generation of a first cryptographic key comprising selecting at least three first input data being:
a first predetermined data or a first data of physical unclonable type; a second predetermined data or a second data of the hardwired type; and a third predetermined data or a third data of the software type.

13 . The method according to claim 12 , wherein the implementing implements a second generation of a second cryptographic key comprising selecting at least three second input data being:
a fourth predetermined data or a fourth data of the physical unclonable type; a fifth predetermined data or the first cryptographic key; and a sixth predetermined data or a fifth data of the software type, wherein assembling the at least three second input data produces an assembled second input data, and wherein applying the assembled second input data into a second cryptographic element produces the second cryptographic key.

14 . The method according to claim 13 , wherein the implementing implements a third generation of a third cryptographic key comprising selecting at least three third input data being:
a seventh predetermined data or a sixth data of the physical unclonable type; an eighth predetermined data or the second cryptographic key; and a nineth predetermined data or a seventh data of the software type, wherein assembling the at least three third input data produces an assembled third input data, and wherein applying the assembled third input data into a third cryptographic element produces the third cryptographic key.

15 . The method according to claim 14 , wherein the first data, the fourth data and the sixth data are a same public data of the physical unclonable type.

16 . A non-transitory computer-readable storage medium including computer executable instruction

Assignees

• Nagravision Sarl

Inventors

• Macchetti Marco
• Perrine Jerome
• Hunacek Didier

Classifications

• H04L9/0869

  involving random numbers or seeds · CPC title

• H04L9/0861 Primary

  Generation of secret information including derivation or calculation of cryptographic keys or passwords · CPC title

• H04L9/3278

  using physically unclonable functions [PUF] · CPC title

• H04L9/14

  using a plurality of keys or algorithms · CPC title

• H04L2209/60

  Digital content management, e.g. content distribution · CPC title