<s>
Authenticated	B-Algorithm
Encryption	I-Algorithm
(	O
AE	O
)	O
are	O
forms	O
of	O
encryption	O
which	O
simultaneously	O
assure	O
the	O
confidentiality	O
and	O
authenticity	B-Error_Name
of	O
data	O
.	O
</s>
<s>
A	O
typical	O
programming	B-Application
interface	I-Application
for	O
an	O
AE	O
implementation	O
provides	O
the	O
following	O
functions	O
:	O
</s>
<s>
Input	O
:	O
plaintext	O
,	O
key	O
,	O
and	O
optionally	O
a	O
header	O
(	O
also	O
known	O
as	O
additional	O
authenticated	O
data	O
,	O
AAD	O
or	O
associated	O
data	O
,	O
AD	O
)	O
in	O
plaintext	O
that	O
will	O
not	O
be	O
encrypted	O
,	O
but	O
will	O
be	O
covered	O
by	O
authenticity	B-Error_Name
protection	O
.	O
</s>
<s>
Output	O
:	O
ciphertext	O
and	O
authentication	O
tag	O
(	O
message	B-Algorithm
authentication	I-Algorithm
code	I-Algorithm
or	O
MAC	O
)	O
.	O
</s>
<s>
The	O
header	O
part	O
is	O
intended	O
to	O
provide	O
authenticity	B-Error_Name
and	O
integrity	O
protection	O
for	O
networking	O
or	O
storage	O
metadata	O
for	O
which	O
confidentiality	O
is	O
unnecessary	O
,	O
but	O
authenticity	B-Error_Name
is	O
desired	O
.	O
</s>
<s>
The	O
need	O
for	O
authenticated	B-Algorithm
encryption	I-Algorithm
emerged	O
from	O
the	O
observation	O
that	O
securely	O
combining	O
separate	O
confidentiality	O
and	O
authentication	O
block	O
cipher	O
operation	O
modes	O
could	O
be	O
error	O
prone	O
and	O
difficult	O
.	O
</s>
<s>
This	O
was	O
confirmed	O
by	O
a	O
number	O
of	O
practical	O
attacks	O
introduced	O
into	O
production	O
protocols	O
and	O
applications	O
by	O
incorrect	O
implementation	O
,	O
or	O
lack	O
of	O
authentication	O
(	O
including	O
SSL/TLS	B-Protocol
)	O
.	O
</s>
<s>
In	O
particular	O
,	O
strong	O
interest	O
in	O
possibly	O
secure	O
modes	O
was	O
sparked	O
by	O
the	O
publication	O
of	O
Charanjit	O
Jutla	O
's	O
integrity-aware	O
CBC	O
and	O
integrity-aware	B-Algorithm
parallelizable	I-Algorithm
,	O
IAPM	B-Algorithm
,	O
modes	O
in	O
2000	O
(	O
see	O
OCB	B-Algorithm
and	O
chronology	O
)	O
.	O
</s>
<s>
Six	O
different	O
authenticated	B-Algorithm
encryption	I-Algorithm
modes	O
(	O
namely	O
offset	B-Algorithm
codebook	I-Algorithm
mode	I-Algorithm
2.0	I-Algorithm
,	O
OCB2.0	O
;	O
Key	B-Algorithm
Wrap	I-Algorithm
;	O
counter	B-Algorithm
with	I-Algorithm
CBC-MAC	I-Algorithm
,	O
CCM	O
;	O
encrypt	B-Algorithm
then	I-Algorithm
authenticate	I-Algorithm
then	I-Algorithm
translate	I-Algorithm
,	O
EAX	O
;	O
encrypt-then-MAC	O
,	O
EtM	O
;	O
and	O
Galois/counter	B-Algorithm
mode	I-Algorithm
,	O
GCM	B-Algorithm
)	O
have	O
been	O
standardized	O
in	O
ISO/IEC	O
19772:2009	O
.	O
</s>
<s>
More	O
authenticated	B-Algorithm
encryption	I-Algorithm
methods	O
were	O
developed	O
in	O
response	O
to	O
NIST	O
solicitation	O
.	O
</s>
<s>
Sponge	B-Algorithm
functions	I-Algorithm
can	O
be	O
used	O
in	O
duplex	O
mode	O
to	O
provide	O
authenticated	B-Algorithm
encryption	I-Algorithm
.	O
</s>
<s>
In	O
2013	O
,	O
the	O
CAESAR	O
competition	O
was	O
announced	O
to	O
encourage	O
design	O
of	O
authenticated	B-Algorithm
encryption	I-Algorithm
modes	O
.	O
</s>
<s>
In	O
2015	O
,	O
ChaCha20-Poly1305	B-Algorithm
is	O
added	O
as	O
an	O
alternative	O
AE	O
construction	O
to	O
GCM	B-Algorithm
in	O
IETF	O
protocols	O
.	O
</s>
<s>
It	O
is	O
required	O
,	O
for	O
example	O
,	O
by	O
network	O
packets	O
or	O
frames	O
where	O
the	O
header	O
needs	O
visibility	O
,	O
the	O
payload	O
needs	O
confidentiality	O
,	O
and	O
both	O
need	O
integrity	O
and	O
authenticity	B-Error_Name
.	O
</s>
<s>
Used	O
in	O
,	O
e.g.	O
,	O
SSH	B-Protocol
.	O
</s>
<s>
Even	O
though	O
the	O
E&M	O
approach	O
has	O
not	O
been	O
proved	O
to	O
be	O
strongly	O
unforgeable	O
in	O
itself	O
,	O
it	O
is	O
possible	O
to	O
apply	O
some	O
minor	O
modifications	O
to	O
SSH	B-Protocol
to	O
make	O
it	O
strongly	O
unforgeable	O
despite	O
the	O
approach	O
.	O
</s>
<s>
AEAD	O
is	O
used	O
in	O
SSL/TLS	B-Protocol
.	O
</s>
<s>
Even	O
though	O
the	O
MtE	O
approach	O
has	O
not	O
been	O
proven	O
to	O
be	O
strongly	O
unforgeable	O
in	O
itself	O
,	O
the	O
SSL/TLS	B-Protocol
implementation	O
has	O
been	O
proven	O
to	O
be	O
strongly	O
unforgeable	O
by	O
Krawczyk	O
who	O
showed	O
that	O
SSL/TLS	B-Protocol
was	O
,	O
in	O
fact	O
,	O
secure	O
because	O
of	O
the	O
encoding	O
used	O
alongside	O
the	O
MtE	O
mechanism	O
.	O
</s>
<s>
Despite	O
the	O
theoretical	O
security	O
,	O
deeper	O
analysis	O
of	O
SSL/TLS	B-Protocol
modeled	O
the	O
protection	O
as	O
MAC-then-pad-then-encrypt	O
,	O
i.e.	O
</s>
<s>
Padding	O
errors	O
often	O
result	O
in	O
the	O
detectable	O
errors	O
on	O
the	O
recipient	O
's	O
side	O
,	O
which	O
in	O
turn	O
lead	O
to	O
padding	B-Application
oracle	I-Application
attacks	I-Application
,	O
such	O
as	O
Lucky	B-Protocol
Thirteen	I-Protocol
.	O
</s>
