A method of authentication of a contactless communication circuit (PICC) by a contactless communication terminal, successively comprising: a first phase comprising the determination by the contactless communication circuit of a first number (A 1) equal to the result of the encryption of a second number (Rb) with a first key (k), the second number (Rb) being a random number, the first phase ending with the transmission of the first number (A 1) by the contactless communication circuit to the contactless communication terminal; a second phase comprising the determination by the contactless communication terminal of a third number (R b_pcd) by decryption of the first number (A 1) by using the first key (k), the determination by the contactless communication terminal of a fourth number (R a_pcd ∥R' b_pcd) based on the third number (R b_pcd) and the determination by the contactless communication terminal of a fifth number (B 1) by encryption in Cipher Block Chaining of the fourth number (R a_pcd ∥R' b_pcd) by using the first key (k) and a first initialization vector equal to "0", the fifth number (B 1) comprising at least first and second juxtaposed portions (B 1,1, B 1,2; B 1,1a, B 1,1b, B 1,2a, B 1,2b), the second phase ending with the transmission of the fifth number (B 1) by the contactless communication terminal to the contactless communication circuit; and a third phase comprising the determination of a sixth number (R' b) by the contactless communication circuit (PICC) based on a second number (R b), the determination of a seventh number (B 1,2_picc) by encryption by a cipher block chaining operating mode of the sixth number (R' b) by using the first key (k) and a second initialization vector equal to the first portion (B 1,1; B 1,1b) of the fifth number (B 1), and the interruption by the contactless communication circuit of the authentication if the seventh number (B 1,2_picc) is different from the second portion (B 1,2), of the fifth number (B 1), the fifth number (B 1) being decrypted by the contactless communication circuit by using the first key (k) to provide the fourth number (R a_pcd ∥R' b_pcd)· a first phase comprising the determination by the contactless communication circuit of a first number (A 1) equal to the result of the encryption of a second number (Rb) with a first key (k), the second number (Rb) being a random number, the first phase ending with the transmission of the first number (A 1) by the contactless communication circuit to the contactless communication terminal; a second phase comprising the determination by the contactless communication terminal of a third number (R b_pcd) by decryption of the first number (A 1) by using the first key (k), the determination by the contactless communication terminal of a fourth number (R a_pcd ∥R' b_pcd) based on the third number (R b_pcd) and the determination by the contactless communication terminal of a fifth number (B 1) by encryption in Cipher Block Chaining of the fourth number (R a_pcd ∥R' b_pcd) by using the first key (k) and a first initialization vector equal to "0", the fifth number (B 1) comprising at least first and second juxtaposed portions (B 1,1, B 1,2; B 1,1a, B 1,1b, B 1,2a, B 1,2b), the second phase ending with the transmission of the fifth number (B 1) by the contactless communication terminal to the contactless communication circuit; and a third phase comprising the determination of a sixth number (R' b) by the contactless communication circuit (PICC) based on a second number (R b), the determination of a seventh number (B 1,2_picc) by encryption by a cipher block chaining operating mode of the sixth number (R' b) by using the first key (k) and a second initialization vector equal to the first portion (B 1,1; B 1,1b) of the fifth number (B 1), and the interruption by the contactless communication circuit of the authentication if the seventh number (B 1,2_picc) is different from the second portion (B 1,2), of the fifth number (B 1), the fifth number (B 1) being decrypted by the contactless communication circuit by using the first key (k) to provide the fourth number (R a_pcd ∥R' b_pcd)·