  CIS2 is a steganographic scheme proposed in the information hiding
literature, belonging into the small category of algorithms being both stego
and topologically secure. Due to its stego-security, this scheme is able to
face attacks that take place into the "watermark only attack" framework. Its
topological security reinforce its capability to face attacks in other
frameworks as "known message attack" or "known original attack", in the
Simmons' prisoner problem. In this research work, the study of topological
properties of C I S 2 is enlarged by describing this scheme as iterations over
the real line, and investigating other security properties of topological
nature as the Lyapunov exponent. Results show that this scheme is able to
withdraw a malicious attacker in the "estimated original attack" context too.
