S-Box In Cryptographic Implementation

Patent metadata

Field	Value
Publication number	US-2016182227-A1
Application number	US-201414577342-A
Country	US
Kind code	A1
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

A method of implementing a cryptographic operation using a substitution box, comprising: specifying a set of self-equivalent functions for the substitution box; determining the minimum diversification number of the substitution box over the set of self-equivalent functions; comparing the minimum diversification number to a threshold value; including and implementing a cryptographic operation with selected substitution box when the minimum diversification number is greater or equal to a threshold value.

First claim

What is claimed is:

1 . A method of implementing a cryptographic operation using a substitution box, comprising:
specifying a set of self-equivalent functions for the substitution box; determining the minimum diversification number of the substitution box over the set of self-equivalent functions; comparing the minimum diversification number to a threshold value; and implementing a cryptographic operation with selected substitution box when the minimum diversification number is greater or equal to a threshold value.

2 . The method of claim 1 , wherein:
set of self-equivalent functions includes a set of input functions and a set of output functions for the substitution box; determining the minimum diversification number of the substitution box further comprises determining the diversification number for each input of each of the input functions; and determining the minimum diversification number among the diversification numbers for each input of each of the input functions.

3 . The method of claim 1 , wherein the cryptographic operation comprises:
receiving input data; encoding the input data using the self-equivalent functions; inputting the encoded input data into the substitution box to obtain output data; and decoding the output data using the output functions.

4 . The method of claim 3 , wherein encoding the input data further comprises:
selecting one of the set of self-equivalent functions based upon the input data having an associated identifier; and securely communicating the associated identifier to a decoder decoding the output data.

5 . The method of claim 4 , wherein decoding the output data further comprises decoding the output data using an self-equivalent function identified by the securely communicated identifier.

6 . The method of claim 1 , wherein input functions of the self-equivalent functions are affine.

7 . The method of claim 6 , wherein output functions of the self-equivalent functions are affine.

8 . The method of claim 2 , wherein the cryptographic operation comprises:
receiving input data; splitting the input data using the self-equivalent functions; inputting the encoded input data into the substitution box to obtain output data; and combining the output data.

9 . The method of claim 1 , wherein the threshold value is 5.

10 . A method of performing a cryptographic operation using a substitution box, comprising:
receiving input data; encoding the input data using input functions of self-equivalent functions associated with the substitution box; applying the substitution box to the encoded data to produce output data wherein the substitution box has a minimum diversification number greater or equal to a predetermined threshold; and decoding the output data using output functions of the self-equivalent functions associated with the substitution box.

11 . The method of claim 10 , wherein the predetermined threshold is 5.

12 . The method of claim 10 , wherein encoding the input data further comprises:
selecting one of the input functions based upon the input data having an associated identifier; and securely communicating the associated identifier to a decoder decoding the output data.

13 . The method of claim 12 , wherein decoding the output data further comprises decoding the output data using the output function identified by the securely communicated identifier.

14 . A method of performing a cryptographic operation using a substitution box, comprising:
receiving input data; splitting the input data using input functions of self-equivalent functions associated with the substitution box; applying the substitution box to the split data to produce output data wherein the substitution box has a minimum diversification number greater or equal to a predetermined threshold; and combining the output data.

15 . The method of claim 14 , wherein the predetermined threshold is 5.

16 . The method of claim 14 , wherein:
splitting the input data further comprises splitting the input data into N split input data using N input functions based upon the input data; and inputting the split input data into the substitution box to obtain output data further comprises inputting the N encoded input data into the substitution box to obtain N output data.

17 . The method of claim 16 , wherein combining the output data further comprises combining the N output data.

Assignees

• Nxp Bv

Inventors

• Michiels Wil
• Hoogerbrugge Jan

Classifications

• H04L9/06 Primary

  the encryption apparatus using shift registers or memories for block-wise {or stream} coding, e.g. DES systems {or RC4; Hash functions; Pseudorandom sequence generators} · CPC title

• H04L9/0631

  Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms · CPC title

• H04L2209/16

  Obfuscation or hiding, e.g. involving white box · CPC title

• H04L9/002 Primary

  Countermeasures against attacks on cryptographic mechanisms (network architectures or network communication protocols for protection against malicious traffic H04L63/1441) · CPC title

• H04L9/0838 Primary

  Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these (network architectures or network communication protocols for key exchange in a packet data network H04L63/061) · CPC title