CRYPTOGRAPHIC PROCESSING METHOD, ASSOCIATED ELECTRONIC DEVICE AND COMPUTER PROGRAM

A cryptographic processing method transforming an input byte into an output byte comprises the following steps:converting a plurality of words, each comprising at least one bit of the input byte, into input cryptograms by application, to each of said words, of a homomorphic encryption function from a first group to a second group provided with an operation;obtaining output cryptograms as a function of the input cryptograms, this obtaining step including at least one processing during which said operation is applied to two intermediate cryptograms, this processing producing a cryptogram that is an image by the homomorphic encryption function of a word including a Boolean logic combination of two bits comprised respectively in two words that are arguments, for the homomorphic encryption function, of said two intermediate cryptograms;determining bits of the output byte by applying respectively to the output cryptograms, an inverse function of the homomorphic encryption function.