<s>
MurmurHash	B-Error_Name
is	O
a	O
non-cryptographic	O
hash	B-Algorithm
function	O
suitable	O
for	O
general	O
hash-based	O
lookup	O
.	O
</s>
<s>
Unlike	O
cryptographic	B-Algorithm
hash	I-Algorithm
functions	I-Algorithm
,	O
it	O
is	O
not	O
specifically	O
designed	O
to	O
be	O
difficult	O
to	O
reverse	O
by	O
an	O
adversary	O
,	O
making	O
it	O
unsuitable	O
for	O
cryptographic	B-Algorithm
purposes	O
.	O
</s>
<s>
The	O
current	O
version	O
is	O
MurmurHash3	O
,	O
which	O
yields	O
a	O
32-bit	O
or	O
128-bit	O
hash	B-Error_Name
value	I-Error_Name
.	O
</s>
<s>
MurmurHash3	O
was	O
released	O
alongside	O
SMHasher	O
—	O
a	O
hash	B-Algorithm
function	I-Algorithm
test	O
suite	O
.	O
</s>
<s>
MurmurHash2A	O
(	O
32-bit	O
,	O
x86	O
)	O
-	O
A	O
fixed	O
variant	O
using	O
Merkle	B-Algorithm
–	I-Algorithm
Damgård	I-Algorithm
construction	I-Algorithm
.	O
</s>
<s>
It	O
is	O
not	O
a	O
true	O
64-bit	O
hash	B-Algorithm
due	O
to	O
insufficient	O
mixing	O
of	O
the	O
stripes	O
.	O
</s>
<s>
The	O
original	O
MurmurHash	B-Error_Name
was	O
created	O
as	O
an	O
attempt	O
to	O
make	O
a	O
faster	O
function	O
than	O
Lookup3	O
.	O
</s>
<s>
Although	O
successful	O
,	O
it	O
had	O
n't	O
been	O
tested	O
thoroughly	O
and	O
was	O
n't	O
capable	O
of	O
providing	O
64-bit	O
hashes	B-Algorithm
as	O
in	O
Lookup3	O
.	O
</s>
<s>
It	O
had	O
a	O
rather	O
elegant	O
design	O
,	O
that	O
would	O
be	O
later	O
built	O
upon	O
in	O
MurmurHash2	O
,	O
combining	O
a	O
multiplicative	O
hash	B-Algorithm
(	O
similar	O
to	O
Fowler	B-Error_Name
–	I-Error_Name
Noll	I-Error_Name
–	I-Error_Name
Vo	I-Error_Name
hash	I-Error_Name
function	I-Error_Name
)	O
with	O
a	O
Xorshift	B-Algorithm
.	O
</s>
<s>
The	O
canonical	O
implementation	O
is	O
in	O
C++	B-Language
,	O
but	O
there	O
are	O
efficient	O
ports	O
for	O
a	O
variety	O
of	O
popular	O
languages	O
,	O
including	O
Python	B-Language
,	O
C	B-Language
,	O
Go	B-Application
,	O
C#	B-Application
,	O
D	B-Application
,	O
,	O
Perl	B-Language
,	O
Ruby	B-Language
,	O
Rust	B-Application
,	O
PHP	B-Application
,	O
Common	B-Language
Lisp	I-Language
,	O
Haskell	B-Language
,	O
Elm	B-Language
,	O
Clojure	B-Language
,	O
Scala	B-Application
,	O
Java	B-Language
,	O
Erlang	B-Operating_System
,	O
Swift	B-Application
,	O
Object	B-Language
Pascal	I-Language
,	O
Kotlin	B-Language
,	O
and	O
JavaScript	B-Language
.	O
</s>
<s>
It	O
has	O
been	O
adopted	O
into	O
a	O
number	O
of	O
open-source	O
projects	O
,	O
most	O
notably	O
libstdc++	B-Language
(	O
ver	O
4.6	O
)	O
,	O
nginx	B-Operating_System
(	O
ver	O
1.0.1	O
)	O
,	O
Rubinius	B-Application
,	O
libmemcached	O
(	O
the	O
C	B-Language
driver	O
for	O
Memcached	B-Application
)	O
,	O
npm	B-Language
(	O
nodejs	O
package	O
manager	O
)	O
,	O
maatkit	O
,	O
Hadoop	B-Application
,	O
Kyoto	O
Cabinet	O
,	O
Cassandra	B-Application
,	O
Solr	B-Language
,	O
vowpal	B-Algorithm
wabbit	I-Algorithm
,	O
Elasticsearch	B-Application
,	O
Guava	B-Language
,	O
Kafka	B-Language
and	O
.	O
</s>
<s>
Hash	B-Algorithm
functions	I-Algorithm
can	O
be	O
vulnerable	O
to	O
collision	B-Algorithm
attacks	I-Algorithm
,	O
where	O
a	O
user	O
can	O
choose	O
input	O
data	O
in	O
such	O
a	O
way	O
so	O
as	O
to	O
intentionally	O
cause	O
hash	B-Algorithm
collisions	O
.	O
</s>
<s>
Jean-Philippe	O
Aumasson	O
and	O
Daniel	O
J	O
.	O
Bernstein	O
were	O
able	O
to	O
show	O
that	O
even	O
implementations	O
of	O
MurmurHash	B-Error_Name
using	O
a	O
randomized	O
seed	O
are	O
vulnerable	O
to	O
so-called	O
HashDoS	O
attacks	O
.	O
</s>
<s>
With	O
the	O
use	O
of	O
differential	O
cryptanalysis	O
they	O
were	O
able	O
to	O
generate	O
inputs	O
that	O
would	O
lead	O
to	O
a	O
hash	B-Algorithm
collision	O
.	O
</s>
<s>
The	O
authors	O
of	O
the	O
attack	O
recommend	O
to	O
use	O
their	O
own	O
SipHash	B-Error_Name
instead	O
.	O
</s>
<s>
A	O
sample	O
C	B-Language
implementation	O
follows	O
(	O
for	O
little-endian	O
CPUs	O
)	O
:	O
</s>
