Kung-Robinson Algorithm

Read Phase: read, write to temporary storage (log)

Validation Phase:
<valid:=true;
for t:=ts+1 to tf do
if (writeset[t] readset[T]= then
valid:=false;
if valid then {write phase; increment counter,
assign T a sequence number}

Write Phase: write log to database

Access Matrix

Lock-key Method

---- combine capability and access control method

Evaluation of three

propagation: control of propagation
Review: determine all subject who have access to an object
Revocation: revocation of access right
Reclamation: when all capabilities disappear, the object is for garbage collection.