<s>
The	O
MD6	B-Algorithm
Message-Digest	B-Algorithm
Algorithm	I-Algorithm
is	O
a	O
cryptographic	B-Algorithm
hash	I-Algorithm
function	I-Algorithm
.	O
</s>
<s>
It	O
uses	O
a	O
Merkle	O
tree-like	O
structure	O
to	O
allow	O
for	O
immense	O
parallel	O
computation	O
of	O
hashes	B-Algorithm
for	O
very	O
long	O
inputs	O
.	O
</s>
<s>
Authors	O
claim	O
a	O
performance	O
of	O
28	O
cycles	O
per	O
byte	O
for	O
MD6-256	O
on	O
an	O
Intel	O
Core	O
2	O
Duo	O
and	O
provable	O
resistance	O
against	O
differential	O
cryptanalysis	O
.	O
</s>
<s>
The	O
source	O
code	O
of	O
the	O
reference	O
implementation	O
was	O
released	O
under	O
MIT	B-License
license	I-License
.	O
</s>
<s>
In	O
December	O
2008	O
,	O
Douglas	O
Held	O
of	O
Fortify	O
Software	O
discovered	O
a	O
buffer	B-General_Concept
overflow	I-General_Concept
in	O
the	O
original	O
MD6	B-Algorithm
hash	B-Algorithm
algorithm	O
's	O
reference	O
implementation	O
.	O
</s>
<s>
MD6	B-Algorithm
was	O
submitted	O
to	O
the	O
NIST	B-Algorithm
SHA-3	I-Algorithm
competition	I-Algorithm
.	O
</s>
<s>
However	O
,	O
on	O
July	O
1	O
,	O
2009	O
,	O
Rivest	O
posted	O
a	O
comment	O
at	O
NIST	O
that	O
MD6	B-Algorithm
is	O
not	O
yet	O
ready	O
to	O
be	O
a	O
candidate	O
for	O
SHA-3	O
because	O
of	O
speed	O
issues	O
,	O
a	O
"	O
gap	O
in	O
the	O
proof	O
that	O
the	O
submitted	O
version	O
of	O
MD6	B-Algorithm
is	O
resistant	O
to	O
differential	O
attacks	O
"	O
,	O
and	O
an	O
inability	O
to	O
supply	O
such	O
a	O
proof	O
for	O
a	O
faster	O
reduced-round	O
version	O
,	O
although	O
Rivest	O
also	O
stated	O
at	O
the	O
MD6	B-Algorithm
website	O
that	O
it	O
is	O
not	O
withdrawn	O
formally	O
.	O
</s>
<s>
MD6	B-Algorithm
did	O
not	O
advance	O
to	O
the	O
second	O
round	O
of	O
the	O
SHA-3	B-Algorithm
competition	I-Algorithm
.	O
</s>
<s>
In	O
September	O
2011	O
,	O
a	O
paper	O
presenting	O
an	O
improved	O
proof	O
that	O
MD6	B-Algorithm
and	O
faster	O
reduced-round	O
versions	O
are	O
resistant	O
to	O
differential	O
attacks	O
was	O
posted	O
to	O
the	O
MD6	B-Algorithm
website	O
.	O
</s>
