A method is provided for secured transfer of an N-byte data element from a
first memory containing the data element to a second memory through a
data bus that is connected between the first memory and the second
memory. According to the method, a transfer rule is defined with at least
one parameter whose value is chosen at random before each transfer of the
data element. The N-byte data element is transferred byte-by-byte through
the data bus in accordance with the transfer rule, with each byte
transition once and only once through the data bus. In a preferred
method, the transfer rule is a permutation of the bytes of the N-byte
data element. Also provided is a programmable circuit having a random
number generator that supplies at least one parameter of a data transfer
rule.