A method for allocating an IP address to a set-top box, comprising: receiving, by a dynamic host configuration protocol, DHCP, server, a verification request message sent by a set-top box, wherein the verification request message carries option information of the DHCP server, which comprises: first identity cipher text information of the set-top box, software version information of the set-top box, and a user serial number, and the first identity cipher text information is generated by the set-top box according to identity information of the set-top box by using a first encryption algorithm; sending, by the DHCP server, the first identity cipher text information of the set-top box, the software version information of the set-top box, and the user serial number included in the option information to an authentication server; deciphering), by the authentication server, the first identity cipher text information according to the user serial number and a preset first decryption algorithm, to obtain the identity information of the set-top box; verifying, by the authentication server, the identity information of the set-top box according to the software version information; sending, by the authentication server, verification success indication information to the dynamic host configuration protocol server if verification is successful, wherein the verification success indication information is used to instruct the dynamic host configuration protocol server to allocate an IP address to the set-top box; and updating the first decryption algorithm; wherein the updating the first decryption algorithm comprises: at the set-top box, receiving the update data including a second encryption algorithm from the broadcast television network at the authentication server, receiving a decryption algorithm update indication message, wherein the decryption algorithm update indication message comprises a second decryption algorithm; and obtaining the second decryption algorithm from the decryption algorithm update indication message, so as to adopt the second decryption algorithm to obtain the identity information of the set-top box from second identity cipher text information after receiving a verification request message sent by the set-top box next time, wherein the second identity cipher text information is generated by the set-top box according to the identity information of the set-top box by using the second encryption algorithm. receiving, by a dynamic host configuration protocol, DHCP, server, a verification request message sent by a set-top box, wherein the verification request message carries option information of the DHCP server, which comprises: first identity cipher text information of the set-top box, software version information of the set-top box, and a user serial number, and the first identity cipher text information is generated by the set-top box according to identity information of the set-top box by using a first encryption algorithm; sending, by the DHCP server, the first identity cipher text information of the set-top box, the software version information of the set-top box, and the user serial number included in the option information to an authentication server; deciphering), by the authentication server, the first identity cipher text information according to the user serial number and a preset first decryption algorithm, to obtain the identity information of the set-top box; verifying, by the authentication server, the identity information of the set-top box according to the software version information; sending, by the authentication server, verification success indication information to the dynamic host configuration protocol server if verification is successful, wherein the verification success indication information is used to instruct the dynamic host configuration protocol server to allocate an IP address to the set-top box; and updating the first decryption algorithm; wherein the updating the first decryption algorithm comprises: at the set-top box, receiving the update data including a second encryption algorithm from the broadcast television network at the authentication server, receiving a decryption algorithm update indication message, wherein the decryption algorithm update indication message comprises a second decryption algorithm; and obtaining the second decryption algorithm from the decryption algorithm update indication message, so as to adopt the second decryption algorithm to obtain the identity information of the set-top box from second identity cipher text information after receiving a verification request message sent by the set-top box next time, wherein the second identity cipher text information is generated by the set-top box according to the identity information of the set-top box by using the second encryption algorithm. at the set-top box, receiving the update data including a second encryption algorithm from the broadcast television network at the authentication server, receiving a decryption algorithm update indication message, wherein the decryption algorithm update indication message comprises a second decryption algorithm; and obtaining the second decryption algorithm from the decryption algorithm update indication message, so as to adopt the second decryption algorithm to obtain the identity information of the set-top box from second identity cipher text information after receiving a verification request message sent by the set-top box next time, wherein the second identity cipher text information is generated by the set-top box according to the identity information of the set-top box by using the second encryption algorithm.