<s>
In	O
cryptography	O
,	O
FEA-M	B-Algorithm
(	O
Fast	O
Encryption	O
Algorithm	O
for	O
Multimedia	O
)	O
is	O
a	O
block	O
cipher	O
developed	O
in	O
2001	O
by	O
X	O
.	O
Yi	O
,	O
C	O
.	O
H	O
.	O
Tan	O
,	O
C	O
.	O
K	O
.	O
Siew	O
,	O
and	O
M	O
.	O
R	O
.	O
Syed	O
.	O
</s>
<s>
With	O
the	O
unusually	O
large	O
block	O
size	O
of	O
4096	O
bits	O
,	O
all	O
of	O
FEA-M	B-Algorithm
'	O
s	O
calculations	O
operate	O
on	O
64×64	O
binary	O
matrices	B-Architecture
.	O
</s>
<s>
Unlike	O
most	O
block	O
ciphers	O
,	O
FEA-M	B-Algorithm
does	O
not	O
use	O
multiple	O
rounds	O
of	O
encryption	O
.	O
</s>
<s>
Since	O
only	O
invertible	O
matrices	B-Architecture
can	O
be	O
used	O
for	O
the	O
key	O
,	O
the	O
effective	O
key	O
size	O
is	O
about	O
4094.2	O
bits	O
.	O
</s>
<s>
FEA-M	B-Algorithm
is	O
insecure	O
;	O
an	O
attack	O
found	O
by	O
Youssef	O
and	O
Tavares	O
(	O
2003	O
)	O
recovers	O
the	O
secret	O
key	O
using	O
only	O
1	O
known	O
plaintext	O
and	O
2	O
chosen	O
plaintexts	O
.	O
</s>
