<s>
RIPEMD	B-Algorithm
(	O
RIPE	O
Message	B-Algorithm
Digest	I-Algorithm
)	O
is	O
a	O
family	O
of	O
cryptographic	B-Algorithm
hash	I-Algorithm
functions	I-Algorithm
developed	O
in	O
1992	O
(	O
the	O
original	O
RIPEMD	B-Algorithm
)	O
and	O
1996	O
(	O
other	O
variants	O
)	O
.	O
</s>
<s>
There	O
are	O
five	O
functions	O
in	O
the	O
family	O
:	O
RIPEMD	B-Algorithm
,	O
RIPEMD-128	B-Algorithm
,	O
RIPEMD-160	B-Algorithm
,	O
RIPEMD-256	B-Algorithm
,	O
and	O
RIPEMD-320	B-Algorithm
,	O
of	O
which	O
RIPEMD-160	B-Algorithm
is	O
the	O
most	O
common	O
.	O
</s>
<s>
The	O
original	O
RIPEMD	B-Algorithm
,	O
as	O
well	O
as	O
RIPEMD-128	B-Algorithm
,	O
is	O
not	O
considered	O
secure	O
because	O
128-bit	O
result	O
is	O
too	O
small	O
and	O
also	O
(	O
for	O
the	O
original	O
RIPEMD	B-Algorithm
)	O
because	O
of	O
design	O
weaknesses	O
.	O
</s>
<s>
The	O
256	O
-	O
and	O
320-bit	O
versions	O
of	O
RIPEMD	B-Algorithm
provide	O
the	O
same	O
level	O
of	O
security	O
as	O
RIPEMD-128	B-Algorithm
and	O
RIPEMD-160	B-Algorithm
,	O
respectively	O
;	O
they	O
are	O
designed	O
for	O
applications	O
where	O
the	O
security	O
level	O
is	O
sufficient	O
but	O
longer	O
hash	B-Algorithm
result	O
is	O
necessary	O
.	O
</s>
<s>
While	O
RIPEMD	B-Algorithm
functions	O
are	O
less	O
popular	O
than	O
SHA-1	B-Algorithm
and	O
SHA-2	B-Algorithm
,	O
they	O
are	O
used	O
,	O
among	O
others	O
,	O
in	O
Bitcoin	B-Protocol
and	O
other	O
cryptocurrencies	O
based	O
on	O
Bitcoin	B-Protocol
.	O
</s>
<s>
The	O
original	O
RIPEMD	B-Algorithm
function	O
was	O
designed	O
in	O
the	O
framework	O
of	O
the	O
EU	O
project	O
RIPE	O
(	O
RACE	O
Integrity	O
Primitives	O
Evaluation	O
)	O
in	O
1992	O
.	O
</s>
<s>
Its	O
design	O
was	O
based	O
on	O
the	O
MD4	B-Algorithm
hash	I-Algorithm
function	O
.	O
</s>
<s>
In	O
1996	O
,	O
in	O
response	O
to	O
security	O
weaknesses	O
found	O
in	O
the	O
original	O
RIPEMD	B-Algorithm
,	O
Hans	O
Dobbertin	O
,	O
Antoon	O
Bosselaers	O
and	O
Bart	O
Preneel	O
at	O
the	O
COSIC	B-General_Concept
research	O
group	O
at	O
the	O
Katholieke	O
Universiteit	O
Leuven	O
in	O
Leuven	O
,	O
Belgium	O
published	O
four	O
strengthened	O
variants	O
:	O
RIPEMD-128	B-Algorithm
,	O
RIPEMD-160	B-Algorithm
,	O
RIPEMD-256	B-Algorithm
,	O
and	O
RIPEMD-320	B-Algorithm
.	O
</s>
<s>
In	O
August	O
2004	O
,	O
a	O
collision	O
was	O
reported	O
for	O
the	O
original	O
RIPEMD	B-Algorithm
.	O
</s>
<s>
This	O
does	O
not	O
apply	O
to	O
RIPEMD-160	B-Algorithm
.	O
</s>
<s>
The	O
160-bit	O
RIPEMD-160	B-Algorithm
hashes	B-Algorithm
(	O
also	O
termed	O
RIPE	O
message	B-Algorithm
digests	I-Algorithm
)	O
are	O
typically	O
represented	O
as	O
40-digit	O
hexadecimal	O
numbers	O
.	O
</s>
<s>
The	O
following	O
demonstrates	O
a	O
43-byte	O
ASCII	B-Protocol
input	O
and	O
the	O
corresponding	O
RIPEMD-160	B-Algorithm
hash	B-Algorithm
:	O
</s>
<s>
RIPEMD-160	B-Algorithm
behaves	O
with	O
the	O
desired	O
avalanche	O
effect	O
of	O
cryptographic	B-Algorithm
hash	I-Algorithm
functions	I-Algorithm
(	O
small	O
changes	O
,	O
e.g.	O
</s>
<s>
changing	O
to	O
,	O
result	O
in	O
a	O
completely	O
different	O
hash	B-Algorithm
)	O
:	O
</s>
<s>
The	O
hash	B-Algorithm
of	O
a	O
zero-length	O
string	O
is	O
:	O
</s>
<s>
Below	O
is	O
a	O
list	O
of	O
cryptography	O
libraries	O
that	O
support	O
RIPEMD	B-Algorithm
(	O
specifically	O
RIPEMD-160	B-Algorithm
)	O
:	O
</s>
