  The cipher block chaining (CBC) block cipher mode of operation presents a
very popular way of encrypting which is used in various applications. In
previous research work, we have mathematically proven that, under some
conditions, this mode of operation can admit a chaotic behavior according to
Devaney. Proving that CBC mode is chaotic is only the beginning of the study of
its security. The next step, which is the purpose of this paper, is to develop
the quantitative study of the chaotic CBC mode of operation by evaluating the
level of sensibility and expansivity for this mode.
