Matrix transposition

A device, comprising:

• memory;
• and
• processing circuitry coupled to the memory, wherein the processing circuitry, in operation, performs a cryptographic operation and protects the performing of the cryptographic operation, the performing the cryptographic operation and the protecting including performing a matrix transformation operation on a matrix having n rows and n columns, where n is a positive integer, each row forming a respective vector of a first set of ordered vectors, the performing the matrix transformation operation including:
• generating a second set of ordered vectors by shifting values of vectors of the first set of ordered vectors in a first direction, wherein a pitch of a shift applied to a vector of the first set of ordered vectors is based on an order number of the vector of the first set of ordered vectors;
• generating a working vector by logically combining vectors of the second set of ordered vectors;
• generating a third set of ordered vectors based on the second set of ordered vectors;
• and
• generating a fourth set of ordered vectors based on the third set of ordered vectors and the working vector.

A system, comprising:

• a processor;
• and
• cryptographic circuitry coupled to the processor, wherein the cryptographic circuitry, in operation, performs a cryptographic operation and protects the performing of the cryptographic operation, the performing the cryptographic operation and the protecting including performing a matrix transformation operation on a matrix having n rows and n columns, where n is a positive integer, each row forming a respective vector of a first set of ordered vectors, the performing the matrix transformation operation including:
• generating a second set of ordered vectors by shifting values of vectors of the first set of ordered vectors in a first direction, wherein a pitch of a shift applied to a vector of the first set of ordered vectors is based on an order number of the vector of the first set of ordered vectors;
• generating a working vector by logically combining vectors of the second set of ordered vectors;
• generating a third set of ordered vectors based on the second set of ordered vectors;
• and
• generating a fourth set of ordered vectors based on the third set of ordered vectors and the working vector.

A non-transitory computer-readable medium having contents which cause cryptographic circuitry to perform a process, the process comprising:

• performing a cryptographic operation;
• and
• protecting the performing of the cryptographic operation, the performing the cryptographic operation and the protecting including performing a matrix transformation operation on a matrix having n rows and n columns, where n is a positive integer, each row forming a respective vector of a first set of ordered vectors, the performing the matrix transformation operation including:
• generating a second set of ordered vectors by shifting values of vectors of the first set of ordered vectors in a first direction, wherein a pitch of a shift applied to a vector of the first set of ordered vectors is based on an order number of the vector of the first set of ordered vectors;
• generating a working vector by logically combining vectors of the second set of ordered vectors;
• generating a third set of ordered vectors based on the second set of ordered vectors;
• and
• generating a fourth set of ordered vectors based on the third set of ordered vectors and the working vector.