Flexible chipset pairing — No restrictions on use of smartcards in secure chip based CAS

In this paper, we propose a new key distribution scheme for the flexible chipset pairing. Chipset pairing is the system that smartcard outputs encrypted CW (Control Word) to the STB, and the STB decrypts an encrypted CW by using the embedded secure chip. The drawback of this chipset pairing is that one smartcard is able to use for only one specified STB since it is the system using the STB bound to a smartcard. Our proposed scheme overcomes a drawback of current chipset pairing by using CRT (Chinese Remainder Theorem). To be specific, with this scheme, one smartcard can be used for multiple STBs, not only single, and apply to current chipset pairing without great changes.