<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
(	O
HPC	B-Algorithm
)	O
is	O
a	O
variable-block-size	O
block	O
cipher	O
designed	O
by	O
Richard	O
Schroeppel	O
,	O
which	O
was	O
an	O
unsuccessful	O
candidate	O
in	O
the	O
competition	O
for	O
selecting	O
the	O
U.S.	O
Advanced	B-Algorithm
Encryption	I-Algorithm
Standard	I-Algorithm
(	O
AES	B-Algorithm
)	O
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
was	O
the	O
only	O
AES	B-Algorithm
candidate	O
designed	O
exclusively	O
by	O
U.S.	O
cryptographers	O
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
is	O
in	O
the	O
public	O
domain	O
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
consists	O
of	O
5	O
different	O
sub-ciphers	O
:	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
algorithms	O
all	O
use	O
64-bit	O
words	O
internally	O
.	O
</s>
<s>
The	O
cipher	O
is	O
designed	O
to	O
run	O
on	O
64-bit	O
machines	B-General_Concept
,	O
which	O
can	O
easily	O
perform	O
simple	O
operations	O
on	O
64-bit	O
words	O
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
can	O
take	O
a	O
key	O
of	O
any	O
number	O
of	O
bits	O
for	O
any	O
one	O
of	O
the	O
five	O
subciphers	O
.	O
</s>
<s>
HPC-Short	O
uses	O
two	O
fixed	O
permutations	O
in	O
addition	O
,	O
and	O
HPC-Tiny	O
consists	O
of	O
many	O
special	O
sub-cases	O
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
can	O
also	O
be	O
used	O
to	O
encrypt	O
values	O
in	O
a	O
range	O
that	O
do	O
not	O
translate	O
to	O
strings	O
with	O
an	O
integral	O
number	O
of	O
bits	O
;	O
for	O
instance	O
,	O
it	O
can	O
encrypt	O
a	O
number	O
from	O
0	O
to	O
N	O
by	O
producing	O
another	O
number	O
from	O
0	O
to	O
N	O
.	O
It	O
does	O
this	O
by	O
using	O
the	O
smallest	O
subcipher	O
that	O
can	O
handle	O
the	O
input	O
as	O
a	O
bit	O
string	O
,	O
and	O
applying	O
it	O
to	O
the	O
input	O
as	O
a	O
bit	O
string	O
,	O
repeatedly	O
,	O
until	O
the	O
output	O
is	O
in	O
the	O
proper	O
range	O
.	O
</s>
<s>
Schroeppel	O
claimed	O
that	O
the	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
was	O
the	O
fastest	O
AES	B-Algorithm
candidate	O
on	O
a	O
64-bit	O
architecture	O
;	O
Schroeppel	O
claimed	O
that	O
it	O
was	O
twice	O
as	O
fast	O
as	O
its	O
nearest	O
competitor	O
,	O
DFC	B-Algorithm
,	O
and	O
three	O
times	O
as	O
fast	O
as	O
the	O
other	O
candidates	O
,	O
and	O
that	O
its	O
performance	O
on	O
a	O
32-bit	O
machine	O
was	O
adequate	O
.	O
</s>
<s>
'	O
s	O
analysis	O
ranked	O
the	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
4th	O
best	O
(	O
376	O
cycles	O
)	O
on	O
a	O
64-bit	O
machine	O
,	O
although	O
for	O
Rijndael	B-Algorithm
and	O
Twofish	B-Algorithm
,	O
the	O
performance	O
was	O
only	O
estimated	O
.	O
</s>
<s>
On	O
a	O
32-bit	O
Pentium	B-Device
,	O
Hasty	O
Pudding	O
encryption	O
was	O
rated	O
by	O
Schneier	O
et	O
al	O
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
's	O
key	O
setup	O
was	O
rated	O
as	O
relatively	O
slow	O
;	O
120000	O
cycles	O
on	O
a	O
Pentium	B-Device
.	O
</s>
<s>
There	O
have	O
been	O
relatively	O
few	O
results	O
on	O
attacking	O
the	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
Early	O
in	O
the	O
AES	B-Algorithm
process	O
,	O
David	O
Wagner	O
noted	O
that	O
relatively	O
large	O
classes	O
of	O
Hasty	O
Pudding	O
keys	O
were	O
equivalent	O
in	O
that	O
they	O
led	O
to	O
the	O
same	O
key	O
table	O
.	O
</s>
<s>
Despite	O
the	O
relative	O
lack	O
of	O
cryptanalysis	O
,	O
the	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
was	O
criticized	O
for	O
its	O
hard-to-understand	O
design	O
and	O
its	O
lack	O
of	O
grounding	O
in	O
research	O
results	O
.	O
</s>
<s>
Schroeppel	O
has	O
offered	O
a	O
bottle	O
of	O
Dom	O
Pérignon	O
champagne	O
to	O
the	O
best	O
paper	O
presenting	O
progress	O
on	O
the	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
It	O
did	O
not	O
make	O
the	O
second	O
round	O
of	O
consideration	O
for	O
AES	B-Algorithm
.	O
</s>
<s>
The	O
Hasty	B-Algorithm
Pudding	I-Algorithm
cipher	I-Algorithm
is	O
considered	O
the	O
first	O
tweakable	O
block	O
cipher	O
.	O
</s>
