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.