Method for performing an encryption of an aes type, and corresponding system and computer program product

Abstract

A polynomial representation (b(x)) in an AES finite field of input bytes (b) of a state matrix (B) is obtained. A plurality (1) of irreducible polynomials (f(y)) and a moving map (ψ) are used to map each polynomial (b(x)) of the polynomial representation into a respective field of polynomials computed with respect to one of the irreducible polynomials (f(y)), to obtain respective moved polynomials (α(y)). The moved polynomials (α(y)) are mapped into a polynomial (a(z)) of a polynomial ring obtained by applying an isomorphism (ω) between the fields of polynomials and the polynomial ring based upon the Chinese remainder theorem (CRT). AES encryption is applied to the polynomial (a(z)). The polynomial (a(z)) is reconverted into the AES finite field to obtain an encrypted state matrix (CB).