A Downloadable Conditional Access System, DCAS, server (110, 310, 420), comprising: a message transmission unit to transmit a DCAS message to a Digital Multimedia Broadcasting, DMB, terminal (120, 320, 410) through a first data channel, the DCAS message including DCAS information, wherein the DCAS information includes at least one of type information of the common conditional access client image, version information of the common conditional access client image, service identifier, ID, information of the second data channel, information about whether the common conditional access client image is encrypted, ID information of the DCAS server (110, 310, 420), hardware version information and software version information of a DCAS platform in the DMB terminal (120, 320, 410), and conditional access solution vendor ID information; an image transmission unit to transmit a common conditional access client image to the DMB terminal (120, 320, 410) through a second data channel, wherein the common conditional access client image includes a conditional access-related software module, wherein the conditional access-related software module indicates an EMM/ECM processing module for CW extraction; and an information transmission unit to perform, after the transmitting, to the DMB terminal (120, 320, 410), the DCAS message by the message transmission unit and the common conditional access client image by the image transmission unit, authentication of the DMB terminal (120, 320, 410) when the DMB terminal (120, 320, 410) requests personalized information through a mobile communication channel, and to transmit the personalized information to the DMB terminal (120, 320, 410) through the mobile communication channel, the personalized information being associated with management of the common conditional access client image and being used for decoding the common conditional access client image. a message transmission unit to transmit a DCAS message to a Digital Multimedia Broadcasting, DMB, terminal (120, 320, 410) through a first data channel, the DCAS message including DCAS information, wherein the DCAS information includes at least one of type information of the common conditional access client image, version information of the common conditional access client image, service identifier, ID, information of the second data channel, information about whether the common conditional access client image is encrypted, ID information of the DCAS server (110, 310, 420), hardware version information and software version information of a DCAS platform in the DMB terminal (120, 320, 410), and conditional access solution vendor ID information; an image transmission unit to transmit a common conditional access client image to the DMB terminal (120, 320, 410) through a second data channel, wherein the common conditional access client image includes a conditional access-related software module, wherein the conditional access-related software module indicates an EMM/ECM processing module for CW extraction; and an information transmission unit to perform, after the transmitting, to the DMB terminal (120, 320, 410), the DCAS message by the message transmission unit and the common conditional access client image by the image transmission unit, authentication of the DMB terminal (120, 320, 410) when the DMB terminal (120, 320, 410) requests personalized information through a mobile communication channel, and to transmit the personalized information to the DMB terminal (120, 320, 410) through the mobile communication channel, the personalized information being associated with management of the common conditional access client image and being used for decoding the common conditional access client image.