A method of supporting a mobility of a Downloadable Conditional Access System (DCAS) host is provided. The method includes: by the second authentication proxy server: performing mutual authentication with a secure micro of the host to generate a session key; requesting an integrated personalization system to download a secure micro client to the host, wherein the secure micro client is encoded using the session key; and transmitting, to a DPS, mapping information between the second authentication proxy server and the secure micro of the host, wherein, in response to receiving the mapping information, the DPS instructs a CAS server to transmit an entitlement management message to the network of the second authentication proxy server without transmitting the entitlement management message to the network of the first authentication proxy server.