<s>
In	O
information	O
security	O
,	O
message	B-Error_Name
authentication	I-Error_Name
or	O
data	B-Error_Name
origin	I-Error_Name
authentication	I-Error_Name
is	O
a	O
property	O
that	O
a	O
message	O
has	O
not	O
been	O
modified	O
while	O
in	O
transit	O
(	O
data	O
integrity	O
)	O
and	O
that	O
the	O
receiving	O
party	O
can	O
verify	O
the	O
source	O
of	O
the	O
message	O
.	O
</s>
<s>
Message	B-Error_Name
authentication	I-Error_Name
does	O
not	O
necessarily	O
include	O
the	O
property	O
of	O
non-repudiation	O
.	O
</s>
<s>
Message	B-Error_Name
authentication	I-Error_Name
is	O
typically	O
achieved	O
by	O
using	O
message	B-Algorithm
authentication	I-Algorithm
codes	I-Algorithm
(	O
MACs	O
)	O
,	O
authenticated	B-Algorithm
encryption	I-Algorithm
(	O
AE	O
)	O
or	O
digital	O
signatures	O
.	O
</s>
<s>
The	O
message	B-Algorithm
authentication	I-Algorithm
code	I-Algorithm
,	O
also	O
known	O
as	O
digital	O
authenticator	O
,	O
is	O
used	O
as	O
an	O
integrity	O
check	O
based	O
on	O
a	O
secret	O
key	O
shared	O
by	O
two	O
parties	O
to	O
authenticate	O
information	O
transmitted	O
between	O
them	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
using	O
a	O
cryptographic	B-Algorithm
hash	I-Algorithm
or	O
symmetric	B-Algorithm
encryption	I-Algorithm
algorithm	I-Algorithm
.	O
</s>
<s>
communicating	O
devices	O
)	O
,	O
and	O
the	O
authentication	O
will	O
fail	O
in	O
the	O
existence	O
of	O
a	O
third	O
party	O
possessing	O
the	O
key	O
since	O
the	O
algorithm	O
will	O
no	O
longer	O
be	O
able	O
to	O
detect	O
forgeries	B-General_Concept
(	O
i.e.	O
</s>
<s>
Some	O
cryptographers	O
distinguish	O
between	O
"	O
message	B-Error_Name
authentication	I-Error_Name
without	O
secrecy	O
"	O
systems	O
–	O
which	O
allow	O
the	O
intended	O
receiver	O
to	O
verify	O
the	O
source	O
of	O
the	O
message	O
,	O
but	O
they	O
do	O
n't	O
bother	O
hiding	O
the	O
plaintext	O
contents	O
of	O
the	O
message	O
–	O
from	O
authenticated	B-Algorithm
encryption	I-Algorithm
systems	O
.	O
</s>
<s>
Some	O
cryptographers	O
have	O
researched	O
subliminal	O
channel	O
systems	O
that	O
send	O
messages	O
that	O
appear	O
to	O
use	O
a	O
"	O
message	B-Error_Name
authentication	I-Error_Name
without	O
secrecy	O
"	O
system	O
,	O
but	O
in	O
fact	O
also	O
transmit	O
a	O
secret	O
message	O
.	O
</s>
<s>
Data	B-Error_Name
origin	I-Error_Name
authentication	I-Error_Name
and	O
non-repudiation	O
have	O
been	O
also	O
studied	O
in	O
the	O
framework	O
of	O
quantum	O
cryptography	O
.	O
</s>
