<s>
In	O
cryptography	O
,	O
Triple	B-Algorithm
DES	I-Algorithm
(	O
3DES	B-Algorithm
or	O
TDES	B-Algorithm
)	O
,	O
officially	O
the	O
Triple	B-Algorithm
Data	I-Algorithm
Encryption	I-Algorithm
Algorithm	I-Algorithm
(	O
TDEA	B-Algorithm
or	O
Triple	B-Algorithm
DEA	I-Algorithm
)	O
,	O
is	O
a	O
symmetric-key	B-Algorithm
block	O
cipher	O
,	O
which	O
applies	O
the	O
DES	B-Algorithm
cipher	O
algorithm	O
three	O
times	O
to	O
each	O
data	O
block	O
.	O
</s>
<s>
The	O
Data	B-Algorithm
Encryption	I-Algorithm
Standard	I-Algorithm
's	O
(	O
DES	B-Algorithm
)	O
56-bit	O
key	O
is	O
no	O
longer	O
considered	O
adequate	O
in	O
the	O
face	O
of	O
modern	O
cryptanalytic	O
techniques	O
and	O
supercomputing	O
power	O
.	O
</s>
<s>
A	O
CVE	O
released	O
in	O
2016	O
,	O
CVE-2016-2183	O
disclosed	O
a	O
major	O
security	O
vulnerability	O
in	O
DES	B-Algorithm
and	O
3DES	B-Algorithm
encryption	O
algorithms	O
.	O
</s>
<s>
This	O
CVE	O
,	O
combined	O
with	O
the	O
inadequate	O
key	O
size	O
of	O
DES	B-Algorithm
and	O
3DES	B-Algorithm
,	O
NIST	O
has	O
deprecated	O
DES	B-Algorithm
and	O
3DES	B-Algorithm
for	O
new	O
applications	O
in	O
2017	O
,	O
and	O
for	O
all	O
applications	O
by	O
the	O
end	O
of	O
2023	O
.	O
</s>
<s>
It	O
has	O
been	O
replaced	O
with	O
the	O
more	O
secure	O
,	O
more	O
robust	O
AES	B-Algorithm
.	O
</s>
<s>
While	O
the	O
government	O
and	O
industry	O
standards	O
abbreviate	O
the	O
algorithm	O
's	O
name	O
as	O
TDES	B-Algorithm
(	O
Triple	B-Algorithm
DES	I-Algorithm
)	O
and	O
TDEA	B-Algorithm
(	O
Triple	B-Algorithm
Data	I-Algorithm
Encryption	I-Algorithm
Algorithm	I-Algorithm
)	O
,	O
RFC	O
1851	O
referred	O
to	O
it	O
as	O
3DES	B-Algorithm
from	O
the	O
time	O
it	O
first	O
promulgated	O
the	O
idea	O
,	O
and	O
this	O
namesake	O
has	O
since	O
come	O
into	O
wide	O
use	O
by	O
most	O
vendors	O
,	O
users	O
,	O
and	O
cryptographers	O
.	O
</s>
<s>
In	O
1978	O
,	O
a	O
triple	O
encryption	O
method	O
using	O
DES	B-Algorithm
with	O
two	O
56-bit	O
keys	O
was	O
proposed	O
by	O
Walter	O
Tuchman	O
;	O
in	O
1981	O
Merkle	O
and	O
Hellman	O
proposed	O
a	O
more	O
secure	O
triple	O
key	O
version	O
of	O
3DES	B-Algorithm
with	O
112	O
bits	O
of	O
security	O
.	O
</s>
<s>
The	O
Triple	B-Algorithm
Data	I-Algorithm
Encryption	I-Algorithm
Algorithm	I-Algorithm
is	O
variously	O
defined	O
in	O
several	O
standards	O
documents	O
:	O
</s>
<s>
The	O
original	O
DES	B-Algorithm
cipher	O
's	O
key	O
size	O
of	O
56	O
bits	O
was	O
generally	O
sufficient	O
when	O
that	O
algorithm	O
was	O
designed	O
,	O
but	O
the	O
availability	O
of	O
increasing	O
computational	O
power	O
made	O
brute-force	O
attacks	O
feasible	O
.	O
</s>
<s>
Triple	B-Algorithm
DES	I-Algorithm
provides	O
a	O
relatively	O
simple	O
method	O
of	O
increasing	O
the	O
key	O
size	O
of	O
DES	B-Algorithm
to	O
protect	O
against	O
such	O
attacks	O
,	O
without	O
the	O
need	O
to	O
design	O
a	O
completely	O
new	O
block	O
cipher	O
algorithm	O
.	O
</s>
<s>
A	O
naive	O
approach	O
to	O
increase	O
strength	O
of	O
a	O
block	O
encryption	O
algorithm	O
with	O
short	O
key	O
length	O
(	O
like	O
DES	B-Algorithm
)	O
would	O
be	O
to	O
use	O
two	O
keys	O
instead	O
of	O
one	O
,	O
and	O
encrypt	O
each	O
block	O
twice	O
:	O
.	O
</s>
<s>
Therefore	O
,	O
Triple	B-Algorithm
DES	I-Algorithm
uses	O
a	O
"	O
key	O
bundle	O
"	O
that	O
comprises	O
three	O
DES	B-Algorithm
keys	O
,	O
,	O
and	O
,	O
each	O
of	O
56	O
bits	O
(	O
excluding	O
parity	B-Error_Name
bits	I-Error_Name
)	O
.	O
</s>
<s>
That	O
is	O
,	O
DES	B-Algorithm
encrypt	O
with	O
,	O
DES	B-Algorithm
decrypt	O
with	O
,	O
then	O
DES	B-Algorithm
encrypt	O
with	O
.	O
</s>
<s>
This	O
improves	O
the	O
strength	O
of	O
the	O
algorithm	O
when	O
using	O
keying	O
option	O
2	O
and	O
provides	O
backward	B-General_Concept
compatibility	I-General_Concept
with	O
DES	B-Algorithm
with	O
keying	O
option	O
3	O
.	O
</s>
<s>
This	O
provides	O
a	O
shorter	O
key	O
length	O
of	O
56*2	O
or	O
112	O
bits	O
and	O
a	O
reasonable	O
compromise	O
between	O
DES	B-Algorithm
and	O
Keying	O
option	O
1	O
,	O
with	O
the	O
same	O
caveat	O
as	O
above	O
.	O
</s>
<s>
This	O
is	O
an	O
improvement	O
over	O
"	O
double	B-Algorithm
DES	I-Algorithm
"	O
which	O
only	O
requires	O
256	O
steps	O
to	O
attack	O
.	O
</s>
<s>
This	O
is	O
backward	B-General_Concept
compatible	I-General_Concept
with	O
DES	B-Algorithm
,	O
since	O
two	O
operations	O
cancel	O
out	O
.	O
</s>
<s>
ISO/IEC	O
18033-3	O
never	O
allowed	O
this	O
option	O
,	O
and	O
NIST	O
no	O
longer	O
allows	O
K1	O
=	O
K2	O
or	O
K2	O
=	O
K3	O
.	O
</s>
<s>
Each	O
DES	B-Algorithm
key	O
is	O
8	O
odd-parity	B-Error_Name
bytes	O
,	O
with	O
56	O
bits	O
of	O
key	O
and	O
8	O
bits	O
of	O
error-detection	O
.	O
</s>
<s>
NIST	O
(	O
and	O
the	O
current	O
TCG	O
specifications	O
version	O
2.0	O
of	O
approved	O
algorithms	O
for	O
Trusted	O
Platform	O
Module	O
)	O
also	O
disallows	O
using	O
any	O
one	O
of	O
the	O
64	O
following	O
64-bit	O
values	O
in	O
any	O
keys	O
(	O
note	O
that	O
32	O
of	O
them	O
are	O
the	O
binary	O
complement	O
of	O
the	O
32	O
others	O
;	O
and	O
that	O
32	O
of	O
these	O
keys	O
are	O
also	O
the	O
reverse	O
permutation	O
of	O
bytes	O
of	O
the	O
32	O
others	O
)	O
,	O
listed	O
here	O
in	O
hexadecimal	O
(	O
in	O
each	O
byte	O
,	O
the	O
least	O
significant	O
bit	O
is	O
an	O
odd-parity	B-Error_Name
generated	O
bit	O
,	O
it	O
is	O
discarded	O
when	O
forming	O
the	O
effective	O
56-bit	O
keys	O
)	O
:	O
</s>
<s>
With	O
these	O
restrictions	O
on	O
allowed	O
keys	O
,	O
Triple	B-Algorithm
DES	I-Algorithm
has	O
been	O
reapproved	O
with	O
keying	O
options	O
1	O
and	O
2	O
only	O
.	O
</s>
<s>
As	O
with	O
all	O
block	O
ciphers	O
,	O
encryption	O
and	O
decryption	O
of	O
multiple	O
blocks	O
of	O
data	O
may	O
be	O
performed	O
using	O
a	O
variety	O
of	O
modes	B-Algorithm
of	I-Algorithm
operation	I-Algorithm
,	O
which	O
can	O
generally	O
be	O
defined	O
independently	O
of	O
the	O
block	O
cipher	O
algorithm	O
.	O
</s>
<s>
For	O
example	O
,	O
ANS	O
X9.52	O
specifies	O
that	O
for	O
cipher	O
block	O
chaining	O
,	O
the	O
initialization	B-Algorithm
vector	I-Algorithm
shall	O
be	O
different	O
each	O
time	O
,	O
whereas	O
ISO/IEC	O
10116	O
does	O
not	O
.	O
</s>
<s>
FIPS	O
PUB	O
46-3	O
and	O
ISO/IEC	O
18033-3	O
define	O
only	O
the	O
single	O
block	O
algorithm	O
,	O
and	O
do	O
not	O
place	O
any	O
restrictions	O
on	O
the	O
modes	B-Algorithm
of	I-Algorithm
operation	I-Algorithm
for	O
multiple	O
blocks	O
.	O
</s>
<s>
In	O
general	O
,	O
Triple	B-Algorithm
DES	I-Algorithm
with	O
three	O
independent	O
keys	O
(	O
keying	O
option1	O
)	O
has	O
a	O
key	O
length	O
of	O
168bits	O
(	O
three	O
56-bit	O
DES	B-Algorithm
keys	O
)	O
,	O
but	O
due	O
to	O
the	O
meet-in-the-middle	O
attack	O
,	O
the	O
effective	O
security	O
it	O
provides	O
is	O
only	O
112bits	O
.	O
</s>
<s>
This	O
can	O
be	O
considered	O
insecure	O
,	O
and	O
,	O
as	O
consequence	O
Triple	B-Algorithm
DES	I-Algorithm
has	O
been	O
deprecated	O
by	O
NIST	O
in	O
2017	O
.	O
</s>
<s>
The	O
short	O
block	O
size	O
of	O
64bits	O
makes	O
3DES	B-Algorithm
vulnerable	O
to	O
block	O
collision	O
attacks	O
if	O
it	O
is	O
used	O
to	O
encrypt	O
large	O
amounts	O
of	O
data	O
with	O
the	O
same	O
key	O
.	O
</s>
<s>
Practical	O
Sweet32	O
attack	O
on	O
3DES-based	O
cipher-suites	O
in	O
TLS	O
required	O
blocks	O
(	O
785GB	O
)	O
for	O
a	O
full	O
attack	O
,	O
but	O
researchers	O
were	O
lucky	O
to	O
get	O
a	O
collision	O
just	O
after	O
around	O
blocks	O
,	O
which	O
took	O
only	O
25minutes	O
.	O
</s>
<s>
OpenSSL	B-Language
does	O
not	O
include	O
3DES	B-Algorithm
by	O
default	O
since	O
version	O
1.1.0	O
(	O
August	O
2016	O
)	O
and	O
considers	O
it	O
a	O
"	O
weak	O
cipher	O
"	O
.	O
</s>
<s>
The	O
electronic	O
payment	O
industry	O
uses	O
Triple	B-Algorithm
DES	I-Algorithm
and	O
continues	O
to	O
develop	O
and	O
promulgate	O
standards	O
based	O
upon	O
it	O
,	O
such	O
as	O
EMV	O
.	O
</s>
<s>
Earlier	O
versions	O
of	O
Microsoft	B-Application
OneNote	I-Application
,	O
Microsoft	B-Application
Outlook	I-Application
2007	O
and	O
Microsoft	B-Protocol
System	I-Protocol
Center	I-Protocol
Configuration	I-Protocol
Manager	I-Protocol
2012	O
use	O
Triple	B-Algorithm
DES	I-Algorithm
to	O
password-protect	O
user	O
content	O
and	O
system	O
data	O
.	O
</s>
<s>
However	O
,	O
in	O
December	O
2018	O
,	O
Microsoft	O
announced	O
the	O
retirement	O
of	O
3DES	B-Algorithm
throughout	O
their	O
Office	O
365	O
service	O
.	O
</s>
<s>
Firefox	B-Application
and	O
Mozilla	B-Application
Thunderbird	I-Application
use	O
Triple	B-Algorithm
DES	I-Algorithm
in	O
CBC	O
mode	O
to	O
encrypt	O
website	O
authentication	O
login	O
credentials	O
when	O
using	O
a	O
master	O
password	O
.	O
</s>
<s>
Below	O
is	O
a	O
list	O
of	O
cryptography	O
libraries	O
that	O
support	O
Triple	B-Algorithm
DES	I-Algorithm
:	O
</s>
<s>
Some	O
implementations	O
above	O
may	O
not	O
include	O
3DES	B-Algorithm
in	O
the	O
default	O
build	O
,	O
in	O
later	O
or	O
more	O
recent	O
versions	O
.	O
</s>
