2. BACKGROUND AND RELATEDWORK
2.1 Problem Description
Covert channels can be described using the analogy of
two prisoners attempting to escape. Simmons proposed the
`prisoner problem' in 1983, which is the standard model used
when describing covert channel communication [13]. The
model describes two people, Alice and Bob, who are impris-
oned and intend to escape. In order to agree upon an escape
plan, they must communicate, but a third party (Wendy the
Warden) monitors their communications. If Wendy detects
anything suspicious, she throws the two into solitary con-
nement, cutting o all communication and making their
escape impossible. In order to hatch an escape plan, Alice
and Bob must exchange messages that appear innocent, but
contain hidden information that Wendy will not notice.