Aadssume you are given two $(02)$ bits to capture access operations on a directory. Answer

the following questions:

a$.$ Name the four operations that can be performed on the file or directory to provide

integrity and availability data

$(5$ marks$).$

b$.$ How would you use Four $(04)$ operations available from the given two $(02)$ bits?

$(5$ marks$).$

c$.$ How would you control the creation and deletion of files? $(5$marks$).$

d$.$ How would you implement the concept of "hidden" files with these access

operations? $($Hidden files are only visible to authorized subjects.$)(5$ marks$)$

a$.$ Define the term a partial ordering. $(5$ marks$).$

b$.$ State the reason partial ordering of abilities does not institute a lattice $(5$ marks$).$

a$.$ What is a reference monitor and its role in operating system access control

security

$(5$ marks$).$

b$.$ Construct the lattice of security levels 'public', 'confidential', and 'strictly

confidential', and for the categories ADMIN, LECTURES, and STUDENTS. $(5$

marks$)$

c$.$ Which objects with security label $($confidential$,($STUDENTS$))$ in a need$-$to$-$

know policy? $(5$ marks$)$

d$.$ How many labels can be constructed from $n$ security levels and $m$ categories? For

illustration, consider the values $n=16$ and $m=64.$ In general, the number of

labels is $n{3}^m.$

$(5$marks$).$

axdvanced security