An authentication method between a server and a client is provided. The authentication method includes transmitting, to the client, an inquiry message including a first modified secret key generated based on a first secret key and a first blinding value, receiving, from the client, a response message including a response value generated based on the first blinding value, a second secret key, and an error value, calculating the error value from the response value, and determining whether authentication of the client has succeeded based on the error value.