  In this paper, a new stream cipher is designed as a clock-controlled one, but
with a new mechanism of altering steps based on system theory in such a way
that the structures used in it are resistant to conventional attacks. Our
proposed algorithm (PALS) uses the main key with the length of 256 bits and a
32-bit message key. The most important criteria considered in designing the
PALS are resistance to known attacks, maximum period, high linear complexity,
and good statistical properties. As a result, the output keystream is very
similar to the perfectly random sequences and resistant to conventional attacks
such as correlation attacks, algebraic attack, divide & conquer attack,
time-memory tradeoff attack and AIDA/cube attacks. The base structure of the
PALS is a clock-controlled combination generator with memory and we obtained
all the features according to design criteria with this structure. PALS can be
used in many applications, especially in financial cryptography due to its
proper security features
