Abstract
Recently, the idea of using chaos to design digital ciphers and analog secure
communication systems has provoked a great deal of research efforts since early 1990s.
Meanwhile, security analysis of various proposed chaotic cryptosystems also attracts
increasing attention, and some chaotic cryptosystems have been found insecure. This paper
discusses the security weaknesses of a proposed cryptographic algorithm with chaos at the
physical level. Some simple linear maps have a well known chaotic behavior in specific
interval. But when studding their long-time dynamics with computers, the result is different
from the true long-time chaotic dynamics, even in a high-precision floating-point arithmetic.
This phenomenon will affect the security of a proposed cryptosystem for practical
implementation with finite computing precision and for the use of the iteration number n as
the secret key. In addition, we present some possible improvements to the encryption scheme
to obtain higher security.