Key management is critical technic of realizing database encryption . in this dissertation, after analysing and comparing several popular key managemet scheme . we make improvement of two-phase key management scheme according to the matter of fact, and achieve two-phase key management scheme from user key to user class key and to data class key, through creating system table in database . at the same time, we work out key using sequence of chaotic nonlinear system . chaotic sequence is complex and recalcitrant to analysis and unpredictableness, and it can offer good complexity and comparable randomness . experiment result proves that using chaotic sequence can create good key 本文首先分析比較了幾種常用的密鑰管理方案,然后針對應用的實際情況,對兩級密鑰管理方案進行了改進,通過在數(shù)據(jù)庫中建立系統(tǒng)表實現(xiàn)了由用戶密鑰得到用戶類密鑰、以及由用戶類密鑰得到數(shù)據(jù)類密鑰的兩級密鑰管理。同時,本文利用由混沌非線性系統(tǒng)迭代產生的序列來生成密鑰?;煦缧蛄薪Y構復雜,難以分析和預測,能提供很好的復雜性、類隨機性。