Abstract: In a first step, electrical conductor tracks (15 to 20) are applied against the bottom and the walls of a cavity (5) for the integrated circuit (IC4) and connected to external contact pads (2) at the same side of the card. Said tracks lie alternately side-by-side at the bottom 7 of the cavity. In a second step, the IC (4) is glued with its surface which does not carry the contacts on said tracks on the bottom (7) of the cavity by means of a non-conducting glue. Then connections are realized by soldering of conductor wires (12) between contacts of the IC and ends of the tracks, and the cavity is filled with a protective resin. Application: Placement of an IC with inverted contacts in an electronic card support.

Abstract: The procedure involves key numbers "d" and "e" and a modulus N, so hat "N" is the product of two factors "p" and "q" which are prime numbers N=p.q, and e.d=1.sub.MOD.phi.(N), where .phi.(N) is the Euler indicator function. The procedure provides enciphered message parts and for deciphering them comprises: a modulus-determining step for determining a deciphering modulus chosen from "p" and "q", a modular reduction step for making a first modular reduction of the number "d" with a modulus equal to said deciphering modulus "(p-1),(q-1)" with the aim of producing a reduced number, a reduction step for making a second modular reduction of each enciphered message part with a modulus equal to said deciphering modulus with the aim of producing a reduced enciphered message part, an exponentiation step for computing a modular exponentiation of each reduced enciphered message part with a modulus equal to said deciphering modulus and with an exponent equal to said reduced number with the aim of restoring said message.