This method uses a tester (T) capable of being connected to an integrated circuit (CI) to be tested. A random number (RNG-C) is generated and ciphered using a key (k) by a cipher algorithm to obtain a password (G_k(RNG)-C). The random number (RNG-C) is sent to the tester (T) in which the received random number (RNG-C) is ciphered using the same key (k) by a same cipher algorithm to generate therein a second password (G_k(RNG)-T). This latter is sent to the integrated circuit (CI) to be compared to the first password (G_k(RNG)-C). The test of the confidential parts (1) of the circuit is only authorised if the two passwords exhibit the required match.