<s>
In	O
cryptography	O
,	O
F-FCSR	B-Algorithm
is	O
a	O
stream	B-Algorithm
cipher	I-Algorithm
developed	O
by	O
Thierry	O
Berger	O
,	O
François	O
Arnault	O
,	O
and	O
Cédric	O
Lauradoux	O
.	O
</s>
<s>
The	O
core	O
of	O
the	O
cipher	O
is	O
a	O
Feedback	B-Algorithm
with	I-Algorithm
Carry	I-Algorithm
Shift	I-Algorithm
Register	I-Algorithm
(	O
FCSR	B-Algorithm
)	O
automaton	O
,	O
which	O
is	O
similar	O
to	O
a	O
LFSR	B-Architecture
,	O
but	O
they	O
perform	O
operations	O
with	O
carries	O
so	O
their	O
transition	O
function	O
is	O
nonlinear	O
.	O
</s>
<s>
F-FCSR	B-Algorithm
was	O
one	O
of	O
the	O
eight	O
algorithms	O
selected	O
for	O
the	O
eCRYPT	O
network	O
's	O
eSTREAM	O
Portfolio	O
,	O
but	O
it	O
was	O
later	O
removed	O
because	O
further	O
analysis	O
showed	O
weaknesses	O
.	O
</s>
