<s>
Kupyna	B-Algorithm
(	O
)	O
is	O
a	O
cryptographic	B-Algorithm
hash	I-Algorithm
function	I-Algorithm
defined	O
in	O
the	O
Ukrainian	O
national	O
standard	O
DSTU	B-Algorithm
7564:2014	I-Algorithm
.	O
</s>
<s>
It	O
was	O
created	O
to	O
replace	O
an	O
obsolete	O
GOST	B-Algorithm
hash	B-Algorithm
function	I-Algorithm
defined	O
in	O
the	O
old	O
standard	O
GOST	B-Algorithm
34.11-95	O
,	O
similar	O
to	O
Streebog	B-Algorithm
hash	B-Algorithm
function	I-Algorithm
standardized	O
in	O
Russia	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
hash	B-Algorithm
function	I-Algorithm
,	O
the	O
standard	O
also	O
describes	O
message	B-Algorithm
authentication	I-Algorithm
code	I-Algorithm
generation	O
using	O
Kupyna	B-Algorithm
with	O
digest	O
sizes	O
256	O
,	O
384	O
and	O
512	O
bits	O
.	O
</s>
<s>
Kupyna	B-Algorithm
hash	B-Algorithm
function	I-Algorithm
uses	O
Davies	O
–	O
Meyer	O
compression	O
function	O
based	O
on	O
Even	B-Algorithm
–	I-Algorithm
Mansour	I-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
The	O
compression	O
function	O
consists	O
of	O
two	O
fixed	O
permutations	O
,	O
T⊕	O
and	O
T+	O
,	O
which	O
are	O
taken	O
from	O
the	O
Kalyna	B-Algorithm
block	O
cipher	O
and	O
consist	O
of	O
four	O
operations	O
:	O
AddRoundConstant	O
,	O
SubBytes	O
,	O
ShiftBytes	O
and	O
MixColumns	O
.	O
</s>
<s>
The	O
round	O
function	O
uses	O
four	O
different	O
S-boxes	B-Algorithm
.	O
</s>
<s>
The	O
function	O
can	O
return	O
a	O
digest	O
of	O
arbitrary	O
length	O
from	O
8	O
to	O
512	O
bits	O
;	O
function	O
which	O
returns	O
n-bit	O
digest	O
is	O
called	O
Kupyna-n	O
.	O
</s>
<s>
Kupyna	B-Algorithm
is	O
Ukrainian	O
name	O
for	O
Polygonatum	O
odoratum	O
.	O
</s>
<s>
Hash	B-Algorithm
values	O
of	O
empty	O
string	O
.	O
</s>
<s>
As	O
with	O
all	O
cryptographic	B-Algorithm
hash	I-Algorithm
functions	I-Algorithm
,	O
even	O
a	O
small	O
change	O
in	O
the	O
message	O
will	O
(	O
with	O
overwhelming	O
probability	O
)	O
result	O
in	O
a	O
hash	B-Algorithm
differing	O
from	O
the	O
original	O
in	O
,	O
on	O
average	O
,	O
half	O
of	O
the	O
output	O
bits	O
,	O
due	O
to	O
the	O
avalanche	O
effect	O
.	O
</s>
<s>
Christoph	O
Dobraunig	O
,	O
Maria	O
Eichlseder	O
,	O
and	O
Florian	O
Mendel	O
describe	O
a	O
collision	O
attack	O
using	O
rebound	O
attack	O
on	O
Kupyna-256	O
reduced	O
to	O
4	O
rounds	O
with	O
time	O
complexity	O
267	O
and	O
on	O
Kupyna-256	O
reduced	O
to	O
5	O
rounds	O
with	O
time	O
complexity	O
2120	O
,	O
based	O
on	O
rebound	O
attacks	O
on	O
Grøstl	B-Algorithm
.	O
</s>
<s>
Jian	O
Zou	O
and	O
Le	O
Dong	O
also	O
describe	O
a	O
collision	O
attack	O
on	O
Kupyna-256	O
reduced	O
to	O
5	O
rounds	O
with	O
time	O
complexity	O
2120	O
,	O
as	O
well	O
as	O
pseudo-preimage	O
attack	O
on	O
6-round	O
Kupyna-256	O
with	O
time	O
and	O
memory	O
complexities	O
2250	O
and	O
on	O
8-round	O
Kupyna-512	O
with	O
time	O
and	O
memory	O
complexities	O
2498	O
.	O
</s>
<s>
They	O
note	O
that	O
these	O
attacks	O
do	O
not	O
threat	O
any	O
security	O
claims	O
of	O
Kupyna	B-Algorithm
.	O
</s>
<s>
Onur	O
Duman	O
published	O
differential	B-General_Concept
fault	I-General_Concept
analysis	I-General_Concept
on	O
Kupyna	B-Algorithm
when	O
it	O
is	O
used	O
for	O
MAC	O
schemes	O
.	O
</s>
