網際網路的快速發展，儲存於資訊系統中的資料，無疑是企業最重要的數位資產，然而因為人員管理制度不當，將對企業造成極大的困擾，尤其是目前利用個人帳號與通行碼來確認使用者身份，已不足以應付，如何針對此項問題，加強系統的安全防護，必定成為未來的重要課題之一。
With the Internet rapid developing, one of the most challenging problems in man-aging large networked systems is the complexity of security administration. Most or-ganizations think that security is paramount to database administrators seeking to pro-tect their gigabytes of vital business data from the prying eyes of unauthorized outsiders and insiders attempting to exceed their authority. All relational database management systems provide some sort of intrinsic security mechanisms designed to minimize these threats.
For the general hierarchy access control problem, Akl and Taylor suggested a well known scheme for the cryptographic key assignment. In this study, we will analyze the advantage and disadvantage of Akl and Taylor's scheme and propose a new scheme of key exchange based on Diffie-Hellman （DH）algorithm. In practical use today, DH algorithm is enabling technology and effectiveness for nearly every encryption in use in the Internet today.
In addition, the aim of this study presents a new digital signature verification model to make the transmission more secure during the process of key exchange. It applies the singly linked to allow a sequence of dynamically allocated storage elements in Log DB. It will use Hash Function algorithm to achieve the integrity and authentication of dynamic data since hash functions are generally faster than digital signature algorithms.
