<s>
In	O
cryptography	O
,	O
Treyfer	B-Algorithm
is	O
a	O
block	O
cipher/MAC	O
designed	O
in	O
1997	O
by	O
Gideon	O
Yuval	O
.	O
</s>
<s>
Aimed	O
at	O
smart	O
card	O
applications	O
,	O
the	O
algorithm	O
is	O
extremely	O
simple	O
and	O
compact	O
;	O
it	O
can	O
be	O
implemented	O
in	O
just	O
29	O
bytes	O
of	O
8051	B-Architecture
machine	B-Language
code	I-Language
.	O
</s>
<s>
Treyfer	B-Algorithm
has	O
a	O
rather	O
small	O
key	O
size	O
and	O
block	O
size	O
of	O
64	O
bits	O
each	O
.	O
</s>
<s>
All	O
operations	O
are	O
byte-oriented	O
,	O
and	O
there	O
is	O
a	O
single	O
8×	O
8-bit	O
S-box	B-Algorithm
.	O
</s>
<s>
The	O
S-box	B-Algorithm
is	O
left	O
undefined	O
;	O
the	O
implementation	O
can	O
simply	O
use	O
whatever	O
data	O
is	O
available	O
in	O
memory	O
.	O
</s>
<s>
In	O
each	O
round	O
,	O
each	O
byte	O
has	O
added	O
to	O
it	O
the	O
S-box	B-Algorithm
value	O
of	O
the	O
sum	O
of	O
a	O
key	O
byte	O
and	O
the	O
previous	O
data	O
byte	O
,	O
then	O
it	O
is	O
rotated	O
left	O
one	O
bit	O
.	O
</s>
<s>
Due	O
to	O
the	O
simplicity	O
of	O
its	O
key	B-Algorithm
schedule	I-Algorithm
,	O
using	O
the	O
same	O
eight	O
key	O
bytes	O
in	O
each	O
round	O
,	O
Treyfer	B-Algorithm
was	O
one	O
of	O
the	O
first	O
ciphers	O
shown	O
to	O
be	O
susceptible	O
to	O
a	O
slide	O
attack	O
.	O
</s>
<s>
This	O
cryptanalysis	O
,	O
which	O
is	O
independent	O
of	O
the	O
number	O
of	O
rounds	O
and	O
the	O
choice	O
of	O
S-box	B-Algorithm
,	O
requires	O
232	O
known	O
plaintexts	O
and	O
244	O
computation	O
time	O
.	O
</s>
