A communications system comprising: an identification information transmission apparatus comprising: an encryption unit configured to encrypt identification information for identifying a person or an object using a first encryption key; a first communications unit configured to transmit the encrypted identification information to an active communications apparatus connected with a first server; and a second communications unit configured to transmit the encrypted identification information to a communications apparatus connected with a second server, and configured to receive a second encryption key different from the first encryption key used to encrypt the identification information from the communications apparatus connected with the second server, wherein the encryption unit is configured to, after reception of the second encryption key, switch the encryption key used to encrypt the identification information from the first encryption key to the second encryption key; wherein the first server is configured to receive the encrypted identification information from the identification information transmission apparatus, determine whether the encryption key needs to be switched, and, if the encryption key needs to be switched, generate the second encryption key; wherein the second server is configured to carry out an authentication operation using the identification information that the communications apparatus receives from the identification information transmission apparatus, and, if authentication is successful, acquire the second encryption key from the first server and transmit the second encryption key to the communications apparatus; and the communications apparatus is configured to, when the communications apparatus receives the second encryption key from the second server, transmit the second encryption key to the identification information transmission apparatus. an identification information transmission apparatus comprising: an encryption unit configured to encrypt identification information for identifying a person or an object using a first encryption key; a first communications unit configured to transmit the encrypted identification information to an active communications apparatus connected with a first server; and a second communications unit configured to transmit the encrypted identification information to a communications apparatus connected with a second server, and configured to receive a second encryption key different from the first encryption key used to encrypt the identification information from the communications apparatus connected with the second server, wherein the encryption unit is configured to, after reception of the second encryption key, switch the encryption key used to encrypt the identification information from the first encryption key to the second encryption key; an encryption unit configured to encrypt identification information for identifying a person or an object using a first encryption key; a first communications unit configured to transmit the encrypted identification information to an active communications apparatus connected with a first server; and a second communications unit configured to transmit the encrypted identification information to a communications apparatus connected with a second server, and configured to receive a second encryption key different from the first encryption key used to encrypt the identification information from the communications apparatus connected with the second server, wherein the encryption unit is configured to, after reception of the second encryption key, switch the encryption key used to encrypt the identification information from the first encryption key to the second encryption key; wherein the first server is configured to receive the encrypted identification information from the identification information transmission apparatus, determine whether the encryption key needs to be switched, and, if the encryption key needs to be switched, generate the second encryption key; wherein the second server is configured to carry out an authentication operation using the identification information that the communications apparatus receives from the identification information transmission apparatus, and, if authentication is successful, acquire the second encryption key from the first server and transmit the second encryption key to the communications apparatus; and the communications apparatus is configured to, when the communications apparatus receives the second encryption key from the second server, transmit the second encryption key to the identification information transmission apparatus.