Research And Implementation Of Head-end Of Conditional Access System Based On SOPC

With the rapid development of Digital television industry, requirementsfor multifarious value-incremental business will increase quickly. Conditionalaccess system (CAS) guarantees that only those entitled customers can watchspecial program. CAS is the key technology for TV service operators to launchthe Pay-TV business as well as all sorts of value-incremental business.Nowadays, CAS has grown mature both at home and abroad， even a lot ofproducts have been sold and used. Nevertheless, as it is concerned with ourlaminated market, the research of diminutive conditional access system whichaims to provide service for country town or countryside still has prodigiousmerit.In such a complex context, we did independent research on the diminutiveconditional access systerm according to DVB standard. The paper mainlyinnovate to perfect CAS on the base of precursor’s achievement.The CASmainly comprises two parts: encryptor and scrambler. The encryptor consistsof ECMG and EMMG. The content included in this paper is as follows:(1) The CAS design has great improvement compared with previous one. Ithas many extended functions: Muxer functions such as rate ajustmentand scheduling output; scrambling TS with multiple pares of CW;Inducing SOPC system to fufill the ethernet comunication with ECMG、EMMG and network administration software.(2) The paper has studied on the common encryption algorithm, and madefuther analyze of CSA、DES、IDEA、RSA algorithms which used in ourCAS.(3) The paper has deep exploration on the principle and the mechanism ofECMG and EMMG. We had applied encryption algorithm to the systemso as to protect CW and fufilled the synchronization of the CW and ECM.All this has been done to make terminals decrypt and descramble the TScorrectly.We make many tests on CAS to prove the functions right. The tests have mainly verify those functions: CSA algorithm, scrambling TS with randomCW, encrytion algorithm,muxer functions,scrambling the program named bycustomer and so on.In future, we will induce SMS、key-circulation mechanism to perfect ourCAS.