The invention relates to a method of authentication of a contactless communication circuit, PICC, by a contactless communication terminal, PCD. Within the PCC, a first number is generated and without encryption, transmitted to the PCD. Within the PCD a second number is determined by decryption of the first number with a first key. The determination of a third number is based on the second number, and the determination of a fourth number is by encryption of the third number with the first key. Decryption of the fourth number with the first key to obtain the third number and an interruption of the authentication if a sixth number obtained from the third number is different from a seventh number, is performed by the PICC.