The first key technique : using plain - text cipher and md5 message - digest algorithm to ensure stb and dhcp server ' s certificate and secure the stb and server ' s communications - the second key technique : using hmac algorithm to realize the safe functions - the third key technique : using ipsec to realize safe functions o those three methods " complexity increases in turn and the degree of the security increases as well which depend on the frame of the methods and the complexity of the algorithm . all theose three methods use the unique serial - number or a special slip - window to defend replay attack 主要采用三种安全方案实现：第一种：利用约定的明文密码验证机顶盒与dhcp服务器的合法身份， md5验证信息合法性：第二种：利用hmac算法验证机顶盒与服务器身份，信息合法性；第三种：利用ipsec验证机顶盒与dhcp服务器身份与信息合法性。每一种方案中皆采用包序号唯一法或者滑动窗口法保证重放攻击。此三种方案复杂度依次增加，安全度依次升高，主要取决于算法的复杂度与架构的搭建。
After strict formal analysis with ban logic , the result have proved that the authentication protocol is secure . the improved access control scheme is realized by the mode of single - key - lock - pair . under new access control scheme , user can own several kinds of access right upon one file under the new scheme without the supposition that the access rights is increase by degrees , and the possibility of overflow problem is significantly reduced by our new method 作为对原双向认证访问控制方案的改进，改进后的双向身份认证协议可以很好的抵抗中间人攻击和重放攻击，经过严密的ban逻辑形式分析和论证，结果表明该协议是安全的；改进后的访问控制方案用单钥-锁对方案实现，除保持了一般单钥-锁对方案的良好动态特性外，在不需要访问权限递增假设下，实现了用户对文件的多种访问控制权限，并大大减小了溢出问题的发生可能
This thesis applies respectively the improved one - time password authentication mechanism and the elliptic curve digital signature algorithm status authentication mechanism to business - to - client ( b2c ) and business - to - business ( b2b ) electronic commerce systems , and provides a new framework model of electronic commerce status authentication systems . at last , this thesis gives an implementation of the status authentication system , which can resist the small - number attack and replay attack 将改进的一次性口令认证技术和有限域上椭圆曲线密码技术分别应用于b2c和b2b电子商务身份认证系统中，提出一种新的电子商务身份认证系统结构模型，并实现了该电子商务身份认证系统，该身份认证系统可以有效地抵御重放攻击和小数攻击。
