A method for encrypting or decrypting a n-tuple of data with a n-tuple of predetermined secret keys, n ≥ 2, for a given non-linear permutation function ( f) and a given linear multiplexing function, the method being characterized in that it comprises data-processing means of equipment implementing steps of: (c) For each element ( a i) of said n-tuple of data, determination of m > n first internal states by application to said element ( a i) of m first operations, each being: - represented by a table ( T ij) stored on data-storage means of the equipment, and - defined as the combination of a single bijective internal encoding ( G ij), of a non-linear sharing function ( D i,E i,F i...), and of the non-linear permutation function ( f) parameterized with the corresponding secret key ( k i), said non-linear sharing functions ( D i,E i,F i...) forming m collections such that the n functions of a collection share any input datum in n fragments whereof the sum is equal to the input datum; all of said first internal states y ij determined for all said elements ( a i) forming m n-tuples of internal states y ij i ∈ 〚 0, n − 1 〛 j ∈ 〚 0, m − 1 〛; (d) For each n-tuple of first internal states, determination of a second internal state ( z j) by application to said internal states ( y ij) of the n-tuple of first internal states of a second operation being: - represented by a table ( T Lj) stored on the data-storage means of the equipment, and - defined as the combination of a second single bijective internal encoding ( G Lj), of the linear multiplexing function, and of the inverses of said first bijective internal encodings ( G ij). (c) For each element ( a i) of said n-tuple of data, determination of m > n first internal states by application to said element ( a i) of m first operations, each being: - represented by a table ( T ij) stored on data-storage means of the equipment, and - defined as the combination of a single bijective internal encoding ( G ij), of a non-linear sharing function ( D i,E i,F i...), and of the non-linear permutation function ( f) parameterized with the corresponding secret key ( k i), said non-linear sharing functions ( D i,E i,F i...) forming m collections such that the n functions of a collection share any input datum in n fragments whereof the sum is equal to the input datum; all of said first internal states y ij determined for all said elements ( a i) forming m n-tuples of internal states y ij i ∈ 〚 0, n − 1 〛 j ∈ 〚 0, m − 1 〛; - represented by a table ( T ij) stored on data-storage means of the equipment, and - defined as the combination of a single bijective internal encoding ( G ij), of a non-linear sharing function ( D i,E i,F i...), and of the non-linear permutation function ( f) parameterized with the corresponding secret key ( k i), said non-linear sharing functions ( D i,E i,F i...) forming m collections such that the n functions of a collection share any input datum in n fragments whereof the sum is equal to the input datum; (d) For each n-tuple of first internal states, determination of a second internal state ( z j) by application to said internal states ( y ij) of the n-tuple of first internal states of a second operation being: - represented by a table ( T Lj) stored on the data-storage means of the equipment, and - defined as the combination of a second single bijective internal encoding ( G Lj), of the linear multiplexing function, and of the inverses of said first bijective internal encodings ( G ij). - represented by a table ( T Lj) stored on the data-storage means of the equipment, and - defined as the combination of a second single bijective internal encoding ( G Lj), of the linear multiplexing function, and of the inverses of said first bijective internal encodings ( G ij).