<s>
In	O
cryptography	O
,	O
the	O
S-1	B-Algorithm
block	I-Algorithm
cipher	I-Algorithm
was	O
a	O
block	O
cipher	O
posted	O
in	O
source	O
code	O
form	O
on	O
Usenet	B-Application
on	O
11	O
August	O
1995	O
.	O
</s>
<s>
Although	O
incorrect	O
security	O
markings	O
immediately	O
indicated	O
a	O
hoax	O
,	O
there	O
were	O
several	O
features	O
of	O
the	O
code	O
which	O
suggested	O
it	O
might	O
be	O
leaked	O
source	O
code	O
for	O
the	O
Skipjack	B-Algorithm
cipher	O
,	O
which	O
was	O
still	O
classified	O
at	O
the	O
time	O
.	O
</s>
<s>
However	O
once	O
David	O
Wagner	O
had	O
discovered	O
a	O
severe	O
design	O
flaw	O
,	O
involving	O
the	O
key	B-Algorithm
schedule	I-Algorithm
but	O
not	O
the	O
underlying	O
round	O
function	O
,	O
it	O
was	O
generally	O
accepted	O
as	O
being	O
a	O
hoax	O
—	O
but	O
one	O
with	O
an	O
astonishing	O
amount	O
of	O
work	O
behind	O
it	O
.	O
</s>
<s>
When	O
Skipjack	B-Algorithm
was	O
eventually	O
declassified	O
in	O
1998	O
,	O
it	O
was	O
indeed	O
found	O
to	O
be	O
totally	O
unlike	O
S-1	O
.	O
</s>
