<s>
Datagram	B-Protocol
Transport	I-Protocol
Layer	I-Protocol
Security	I-Protocol
(	O
DTLS	B-Protocol
)	O
is	O
a	O
communications	O
protocol	O
providing	O
security	O
to	O
datagram-based	O
applications	O
by	O
allowing	O
them	O
to	O
communicate	O
in	O
a	O
way	O
designed	O
to	O
prevent	O
eavesdropping	O
,	O
tampering	O
,	O
or	O
message	O
forgery	O
.	O
</s>
<s>
The	O
DTLS	B-Protocol
protocol	O
is	O
based	O
on	O
the	O
stream-oriented	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
(	O
TLS	O
)	O
protocol	O
and	O
is	O
intended	O
to	O
provide	O
similar	O
security	O
guarantees	O
.	O
</s>
<s>
The	O
DTLS	B-Protocol
protocol	O
datagram	B-Protocol
preserves	O
the	O
semantics	O
of	O
the	O
underlying	O
transport	O
—	O
the	O
application	O
does	O
not	O
suffer	O
from	O
the	O
delays	O
associated	O
with	O
stream	B-Architecture
protocols	O
,	O
but	O
because	O
it	O
uses	O
UDP	B-Protocol
or	O
SCTP	B-Protocol
,	O
the	O
application	O
has	O
to	O
deal	O
with	O
packet	B-Protocol
reordering	I-Protocol
,	O
loss	O
of	O
datagram	B-Protocol
and	O
data	O
larger	O
than	O
the	O
size	O
of	O
a	O
datagram	B-Protocol
network	B-Protocol
packet	I-Protocol
.	O
</s>
<s>
Because	O
DTLS	B-Protocol
uses	O
UDP	B-Protocol
or	O
SCTP	B-Protocol
rather	O
than	O
TCP	O
,	O
it	O
avoids	O
the	O
"	O
TCP	O
meltdown	O
problem	O
"	O
,	O
when	O
being	O
used	O
to	O
create	O
a	O
VPN	O
tunnel	O
.	O
</s>
<s>
The	O
following	O
documents	O
define	O
DTLS	B-Protocol
:	O
</s>
<s>
for	O
use	O
with	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	B-Protocol
)	O
,	O
</s>
<s>
for	O
use	O
with	O
Datagram	B-Protocol
Congestion	I-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
DCCP	B-Protocol
)	O
,	O
</s>
<s>
for	O
use	O
with	O
Stream	B-Protocol
Control	I-Protocol
Transmission	I-Protocol
Protocol	I-Protocol
(	O
SCTP	B-Protocol
)	O
encapsulation	O
,	O
</s>
<s>
for	O
use	O
with	O
Secure	B-Protocol
Real-time	I-Protocol
Transport	I-Protocol
Protocol	I-Protocol
(	O
SRTP	O
)	O
subsequently	O
called	O
DTLS-SRTP	O
in	O
a	O
draft	O
with	O
Secure	O
Real-Time	O
Transport	O
Control	O
Protocol	O
(	O
SRTCP	B-Protocol
)	O
.	O
</s>
<s>
DTLS	B-Protocol
1.0	O
is	O
based	O
on	O
TLS	O
1.1	O
,	O
DTLS	B-Protocol
1.2	O
is	O
based	O
on	O
TLS	O
1.2	O
,	O
and	O
DTLS	B-Protocol
1.3	O
is	O
based	O
on	O
TLS	O
1.3	O
.	O
</s>
<s>
There	O
is	O
no	O
DTLS	B-Protocol
1.1	O
because	O
this	O
version-number	O
was	O
skipped	O
in	O
order	O
to	O
harmonize	O
version	O
numbers	O
with	O
TLS	O
.	O
</s>
<s>
Like	O
previous	O
DTLS	B-Protocol
versions	O
,	O
DTLS	B-Protocol
1.3	O
is	O
intended	O
to	O
provide	O
"	O
equivalent	O
security	O
guarantees	O
[	O
to	O
TLS	O
1.3	O
]	O
with	O
the	O
exception	O
of	O
order	O
protection/non	O
-replayability	O
"	O
.	O
</s>
<s>
Cisco	O
AnyConnect	O
VPN	O
Client	O
uses	O
TLS	O
and	O
invented	O
DTLS	B-Protocol
based	O
VPN	O
.	O
</s>
<s>
OpenConnect	B-Application
is	O
an	O
open	O
source	O
AnyConnect-compatible	O
client	O
and	O
ocserv	B-Application
server	O
that	O
supports	O
(	O
D	O
)	O
TLS	O
.	O
</s>
<s>
Web	O
browsers	O
:	O
Google	B-Application
Chrome	I-Application
,	O
Opera	B-Application
and	O
Firefox	B-Application
support	O
DTLS-SRTP	O
for	O
WebRTC	B-Protocol
.	O
</s>
<s>
Firefox	B-Application
86	O
and	O
onward	O
does	O
not	O
support	O
DTLS	B-Protocol
1.0	O
.	O
</s>
<s>
In	O
February	O
2013	O
two	O
researchers	O
from	O
Royal	O
Holloway	O
,	O
University	O
of	O
London	O
discovered	O
a	O
timing	O
attack	O
which	O
allowed	O
them	O
to	O
recover	O
(	O
parts	O
of	O
the	O
)	O
plaintext	O
from	O
a	O
DTLS	B-Protocol
connection	O
using	O
the	O
OpenSSL	B-Language
or	O
GnuTLS	B-Application
implementation	O
of	O
DTLS	B-Protocol
when	O
Cipher	O
Block	O
Chaining	O
mode	O
encryption	O
was	O
used	O
.	O
</s>
