Method for verifying the validity of a certificate of a second party by an identity card of a proving party through a third party, wherein: a) operating a certification authority to issue an assertion token which is a signature of a message with a private key of the certification authority, said message comprising an anonymous identifier associated to a certificate of the second party, b) transmitting the assertion token and the second party certificate from the second party to the identity card in response to a request of access to a service of the service provider, c) in response to receiving the assertion token and the certificate, operating the identity card to verify the correctness of the signature of the assertion token and the correctness of a certification chain and upon successful verification, encrypting an anonymous identifier of the certificate with a public encryption key PKEnc CA] of the certification authority, d) operating (32, 33) the identity card to transmit to the third party a name/identifier CAref of the certification authority issuing the certificate and the encrypted anonymous identifier, e) - in response to receiving the name/identifier CAref and the encrypted anonymous identifier, operating the third party to request the revocation status of the certificate by forwarding the encrypted anonymous identifier to the certification authority associated to the received name/identifier CAref, f) - in response to receiving the encrypted anonymous identifier, operating the certification authority to decrypt the encrypted anonymous identifier and to check the revocation status of the certificate associated to the decrypted anonymous identifier, g) - operating the certification authority to send the result of the revocation status to the third party which transmits it to the identity card. a) operating a certification authority to issue an assertion token which is a signature of a message with a private key of the certification authority, said message comprising an anonymous identifier associated to a certificate of the second party, b) transmitting the assertion token and the second party certificate from the second party to the identity card in response to a request of access to a service of the service provider, c) in response to receiving the assertion token and the certificate, operating the identity card to verify the correctness of the signature of the assertion token and the correctness of a certification chain and upon successful verification, encrypting an anonymous identifier of the certificate with a public encryption key PKEnc CA] of the certification authority, d) operating (32, 33) the identity card to transmit to the third party a name/identifier CAref of the certification authority issuing the certificate and the encrypted anonymous identifier, e) - in response to receiving the name/identifier CAref and the encrypted anonymous identifier, operating the third party to request the revocation status of the certificate by forwarding the encrypted anonymous identifier to the certification authority associated to the received name/identifier CAref, f) - in response to receiving the encrypted anonymous identifier, operating the certification authority to decrypt the encrypted anonymous identifier and to check the revocation status of the certificate associated to the decrypted anonymous identifier, g) - operating the certification authority to send the result of the revocation status to the third party which transmits it to the identity card.