The first level is the traditional DiscretionaryAccessControl (DAC).
第一级是传统的自主访问控制(Discretionary Access Control, DAC)。
2
DiscretionaryAccessControl is one of necessary and most common secure mechanisms in the secure operating system.
自主访问控制机制是安全操作系统必不可少的、应用最广泛的安全机制之一。
3
Discretionaryaccesscontrol (DAC) is the kernel of most protection mechanism, and the research on safety of DAC concerns whether rights can be leaked to unauthorized subjects.