<s>
High-bandwidth	B-Protocol
Digital	I-Protocol
Content	I-Protocol
Protection	I-Protocol
(	O
HDCP	B-Protocol
)	O
is	O
a	O
form	O
of	O
digital	O
copy	B-Application
protection	I-Application
developed	O
by	O
Intel	O
Corporation	O
to	O
prevent	O
copying	O
of	O
digital	O
audio	O
and	O
video	O
content	O
as	O
it	O
travels	O
across	O
connections	O
.	O
</s>
<s>
Types	O
of	O
connections	O
include	O
DisplayPort	B-Protocol
(	O
DP	B-Protocol
)	O
,	O
Digital	B-Protocol
Visual	I-Protocol
Interface	I-Protocol
(	O
DVI	B-Protocol
)	O
,	O
and	O
High-Definition	B-Protocol
Multimedia	I-Protocol
Interface	I-Protocol
(	O
HDMI	B-Protocol
)	O
,	O
as	O
well	O
as	O
less	O
popular	O
or	O
now	O
deprecated	O
protocols	O
like	O
Gigabit	O
Video	O
Interface	O
(	O
GVIF	O
)	O
and	O
Unified	B-Protocol
Display	I-Protocol
Interface	I-Protocol
(	O
UDI	B-Protocol
)	O
.	O
</s>
<s>
The	O
system	O
is	O
meant	O
to	O
stop	O
HDCP-encrypted	O
content	O
from	O
being	O
played	O
on	O
unauthorized	O
devices	O
or	O
devices	O
which	O
have	O
been	O
modified	O
to	O
copy	O
HDCP	B-Protocol
content	O
.	O
</s>
<s>
In	O
order	O
to	O
make	O
a	O
device	O
that	O
plays	O
HDCP-enabled	O
content	O
,	O
the	O
manufacturer	O
must	O
obtain	O
a	O
license	O
for	O
the	O
patent	O
from	O
Intel	O
subsidiary	O
Digital	O
Content	B-Application
Protection	I-Application
LLC	O
,	O
pay	O
an	O
annual	O
fee	O
,	O
and	O
submit	O
to	O
various	O
conditions	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
device	O
cannot	O
be	O
designed	O
to	O
copy	O
;	O
it	O
must	O
"	O
frustrate	O
attempts	O
to	O
defeat	O
the	O
content	B-Application
protection	I-Application
requirements	O
"	O
;	O
it	O
must	O
not	O
transmit	O
high	O
definition	O
protected	O
video	O
to	O
non-HDCP	O
receivers	O
;	O
and	O
DVD-Audio	O
works	O
can	O
be	O
played	O
only	O
at	O
CD-audio	O
quality	O
by	O
non-HDCP	O
digital	O
audio	O
outputs	O
(	O
analog	O
audio	O
outputs	O
have	O
no	O
quality	O
limits	O
)	O
.	O
</s>
<s>
If	O
the	O
device	O
has	O
a	O
feature	O
like	O
Intel	O
Management	O
Engine	O
disabled	O
,	O
HDCP	B-Protocol
will	O
not	O
work	O
.	O
</s>
<s>
Cryptanalysis	O
researchers	O
demonstrated	O
flaws	O
in	O
HDCP	B-Protocol
as	O
early	O
as	O
2001	O
.	O
</s>
<s>
In	O
September	O
2010	O
,	O
an	O
HDCP	B-Protocol
master	O
key	O
that	O
allows	O
for	O
the	O
generation	O
of	O
valid	O
device	O
keys	O
was	O
released	O
to	O
the	O
public	O
,	O
rendering	O
the	O
key	O
revocation	O
feature	O
of	O
HDCP	B-Protocol
useless	O
.	O
</s>
<s>
HDCP	B-Protocol
uses	O
three	O
systems	O
:	O
</s>
<s>
Encryption	O
of	O
the	O
data	O
sent	O
over	O
DisplayPort	B-Protocol
,	O
DVI	B-Protocol
,	O
HDMI	B-Protocol
,	O
GVIF	O
,	O
or	O
UDI	B-Protocol
interfaces	O
prevents	O
eavesdropping	O
of	O
information	O
and	O
man-in-the-middle	O
attacks	O
.	O
</s>
<s>
Each	O
HDCP-capable	O
device	O
has	O
a	O
unique	O
set	O
of	O
40	O
56-bit	O
keys	O
.	O
</s>
<s>
Each	O
KSV	O
consists	O
of	O
40	O
bits	O
(	O
one	O
bit	O
for	O
each	O
HDCP	B-Protocol
key	O
)	O
,	O
with	O
20	O
bits	O
set	O
to	O
0	O
and	O
20	O
bits	O
set	O
to	O
1	O
.	O
</s>
<s>
Each	O
device	O
adds	O
its	O
own	O
secret	O
keys	O
together	O
(	O
using	O
unsigned	B-Algorithm
addition	O
modulo	O
256	O
)	O
according	O
to	O
a	O
KSV	O
received	O
from	O
another	O
device	O
.	O
</s>
<s>
Encryption	O
is	O
done	O
by	O
a	O
stream	B-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
Each	O
decoded	O
pixel	B-Algorithm
is	O
encrypted	O
by	O
applying	O
an	O
XOR	B-Application
operation	O
with	O
a	O
24-bit	O
number	O
produced	O
by	O
a	O
generator	O
.	O
</s>
<s>
The	O
HDCP	B-Protocol
specifications	O
ensure	O
constant	O
updating	O
of	O
keys	O
after	O
each	O
encoded	O
frame	O
.	O
</s>
<s>
HDCP	B-Protocol
devices	O
are	O
generally	O
divided	O
into	O
three	O
categories	O
:	O
</s>
<s>
Examples	O
include	O
set-top	O
boxes	O
,	O
DVD	O
,	O
HD	B-Operating_System
DVD	I-Operating_System
and	O
Blu-ray	O
Disc	O
players	O
,	O
and	O
computer	O
video	O
cards	O
.	O
</s>
<s>
A	O
source	O
has	O
only	O
an	O
HDCP/HDMI	O
transmitter	O
.	O
</s>
<s>
A	O
sink	O
has	O
one	O
or	O
more	O
HDCP/HDMI	O
receivers	O
.	O
</s>
<s>
Repeaters	O
have	O
HDMI	B-Protocol
inputs	O
and	O
outputs	O
.	O
</s>
<s>
Each	O
device	O
may	O
contain	O
one	O
or	O
more	O
HDCP	B-Protocol
transmitters	O
and/or	O
receivers	O
.	O
</s>
<s>
(	O
A	O
single	O
transmitter	O
or	O
receiver	O
chip	O
may	O
combine	O
HDCP	B-Protocol
and	O
HDMI	B-Protocol
functionality	O
.	O
)	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
the	O
Federal	O
Communications	O
Commission	O
(	O
FCC	O
)	O
approved	O
HDCP	B-Protocol
as	O
a	O
"	O
Digital	O
Output	O
Protection	O
Technology	O
"	O
on	O
4	O
August	O
2004	O
.	O
</s>
<s>
The	O
FCC	O
's	O
Broadcast	B-Device
flag	I-Device
regulations	O
,	O
which	O
were	O
struck	O
down	O
by	O
the	O
United	O
States	O
Court	O
of	O
Appeals	O
for	O
the	O
District	O
of	O
Columbia	O
Circuit	O
,	O
would	O
have	O
required	O
DRM	O
technologies	O
on	O
all	O
digital	O
outputs	O
from	O
HDTV	O
signal	O
demodulators	O
.	O
</s>
<s>
Congress	O
is	O
still	O
considering	O
legislation	O
that	O
would	O
implement	O
something	O
similar	O
to	O
the	O
Broadcast	B-Device
Flag	I-Device
.	O
</s>
<s>
The	O
HDCP	B-Protocol
standard	O
is	O
more	O
restrictive	O
than	O
the	O
FCC	O
's	O
Digital	O
Output	O
Protection	O
Technology	O
requirement	O
.	O
</s>
<s>
HDCP	B-Protocol
bans	O
compliant	O
products	O
from	O
converting	O
HDCP-restricted	O
content	O
to	O
full-resolution	O
analog	O
form	O
,	O
presumably	O
in	O
an	O
attempt	O
to	O
reduce	O
the	O
size	O
of	O
the	O
analog	O
hole	O
.	O
</s>
<s>
On	O
19	O
January	O
2005	O
,	O
the	O
European	O
Information	O
,	O
Communications	O
,	O
and	O
Consumer	O
Electronics	O
Technology	O
Industry	O
Associations	O
(	O
EICTA	O
)	O
announced	O
that	O
HDCP	B-Protocol
is	O
a	O
required	O
component	O
of	O
the	O
European	O
"	O
HD	O
ready	O
"	O
label	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
Vista	I-Application
and	O
Windows	B-Device
7	I-Device
both	O
use	O
HDCP	B-Protocol
in	O
computer	O
graphics	O
cards	O
and	O
monitors	O
.	O
</s>
<s>
HDCP	B-Protocol
strippers	O
decrypt	O
the	O
HDCP	B-Protocol
stream	O
and	O
transmit	O
an	O
unencrypted	O
HDMI	B-Protocol
video	O
signal	O
so	O
it	O
will	O
work	O
in	O
a	O
non-HDCP	O
display	O
.	O
</s>
<s>
It	O
is	O
currently	O
unclear	O
whether	O
such	O
devices	O
would	O
remain	O
working	O
if	O
the	O
HDCP	B-Protocol
licensing	O
body	O
issued	O
key-revocation	O
lists	O
,	O
which	O
may	O
be	O
installed	O
via	O
new	O
media	O
(	O
e.g.	O
</s>
<s>
In	O
2001	O
,	O
Scott	O
Crosby	O
of	O
Carnegie	O
Mellon	O
University	O
wrote	O
a	O
paper	O
with	O
Ian	O
Goldberg	O
,	O
Robert	O
Johnson	O
,	O
Dawn	O
Song	O
,	O
and	O
David	O
Wagner	O
called	O
"	O
A	O
Cryptanalysis	O
of	O
the	O
High-bandwidth	B-Protocol
Digital	I-Protocol
Content	I-Protocol
Protection	I-Protocol
System	O
"	O
,	O
and	O
presented	O
it	O
at	O
ACM-CCS8	O
DRM	O
Workshop	O
on	O
5	O
November	O
.	O
</s>
<s>
The	O
authors	O
concluded	O
that	O
HDCP	B-Protocol
's	O
linear	O
key	O
exchange	O
is	O
a	O
fundamental	O
weakness	O
,	O
and	O
discussed	O
ways	O
to	O
:	O
</s>
<s>
Around	O
the	O
same	O
time	O
,	O
Niels	O
Ferguson	O
independently	O
claimed	O
to	O
have	O
broken	O
the	O
HDCP	B-Protocol
scheme	O
,	O
but	O
he	O
did	O
not	O
publish	O
his	O
research	O
,	O
citing	O
legal	O
concerns	O
arising	O
from	O
the	O
controversial	O
Digital	O
Millennium	O
Copyright	O
Act	O
.	O
</s>
<s>
In	O
November	O
2011	O
Professor	O
Tim	O
Güneysu	O
of	O
Ruhr-Universität	O
Bochum	O
revealed	O
he	O
had	O
broken	O
the	O
HDCP	B-Protocol
1.3	O
encryption	O
standard	O
.	O
</s>
<s>
On	O
14	O
September	O
2010	O
,	O
Engadget	B-Application
reported	O
the	O
release	O
of	O
a	O
possible	O
genuine	O
HDCP	B-Protocol
master	O
key	O
which	O
can	O
create	O
device	O
keys	O
that	O
can	O
authenticate	O
with	O
other	O
HDCP	B-Protocol
compliant	O
devices	O
without	O
obtaining	O
valid	O
keys	O
from	O
The	O
Digital	O
Content	B-Application
Protection	I-Application
LLC	O
.	O
</s>
<s>
This	O
master	O
key	O
would	O
neutralize	O
the	O
key	O
revocation	O
feature	O
of	O
HDCP	B-Protocol
,	O
because	O
new	O
keys	O
can	O
be	O
created	O
when	O
old	O
ones	O
are	O
revoked	O
.	O
</s>
<s>
Since	O
the	O
master	O
key	O
is	O
known	O
,	O
it	O
follows	O
that	O
an	O
unlicensed	O
HDCP	B-Protocol
decoding	O
device	O
could	O
simply	O
use	O
the	O
master	O
key	O
to	O
dynamically	O
generate	O
new	O
keys	O
on	O
the	O
fly	O
,	O
making	O
revocation	O
impossible	O
.	O
</s>
<s>
It	O
was	O
not	O
immediately	O
clear	O
who	O
discovered	O
the	O
key	O
or	O
how	O
they	O
discovered	O
it	O
,	O
though	O
the	O
discovery	O
was	O
announced	O
via	O
a	O
Twitter	B-Application
update	O
which	O
linked	O
to	O
a	O
Pastebin	O
snippet	O
containing	O
the	O
key	O
and	O
instructions	O
on	O
how	O
to	O
use	O
it	O
.	O
</s>
<s>
Engadget	B-Application
said	O
the	O
attacker	O
may	O
have	O
used	O
the	O
method	O
proposed	O
by	O
Crosby	O
in	O
2001	O
to	O
retrieve	O
the	O
master	O
key	O
,	O
although	O
they	O
cited	O
a	O
different	O
researcher	O
.	O
</s>
<s>
Intel	O
has	O
threatened	O
legal	O
action	O
against	O
anyone	O
producing	O
hardware	O
to	O
circumvent	O
the	O
HDCP	B-Protocol
,	O
possibly	O
under	O
the	O
Digital	O
Millennium	O
Copyright	O
Act	O
.	O
</s>
<s>
The	O
attack	O
used	O
the	O
fact	O
that	O
the	O
pairing	O
process	O
sends	O
the	O
Km	O
key	O
obfuscated	O
with	O
an	O
XOR	B-Application
.	O
</s>
<s>
Further	O
,	O
the	O
input	O
parameters	O
for	O
the	O
XOR	B-Application
and	O
the	O
AES	B-Algorithm
above	O
it	O
are	O
fixed	O
from	O
the	O
receiver	O
side	O
,	O
meaning	O
the	O
transmitter	O
can	O
enforce	O
repeating	O
the	O
same	O
operation	O
.	O
</s>
<s>
Since	O
E( )	O
is	O
based	O
on	O
XOR	B-Application
it	O
undoes	O
itself	O
,	O
thus	O
exposing	O
the	O
Km	O
of	O
the	O
legitimate	O
device	O
.	O
</s>
<s>
An	O
episode	O
of	O
AMC	O
's	O
series	O
Breaking	O
Bad	O
was	O
leaked	O
to	O
the	O
Internet	O
in	O
UHD	O
format	O
;	O
its	O
metadata	O
indicated	O
it	O
was	O
an	O
HDMI	B-Protocol
cap	O
,	O
meaning	O
it	O
was	O
captured	O
through	O
HDMI	B-Protocol
interface	O
that	O
removed	O
HDCP	B-Protocol
2.2	O
protection	O
.	O
</s>
<s>
On	O
4	O
November	O
2015	O
,	O
Chinese	O
company	O
LegendSky	O
Tech	O
Co.	O
,	O
already	O
known	O
for	O
their	O
other	O
HDCP	B-Protocol
rippers/splitters	O
under	O
the	O
HDFury	O
brand	O
,	O
released	O
the	O
HDFury	O
Integral	O
,	O
a	O
device	O
that	O
can	O
remove	O
HDCP	B-Protocol
2.2	O
from	O
HDCP-enabled	O
UHD	O
works	O
.	O
</s>
<s>
On	O
31	O
December	O
2015	O
,	O
Warner	O
Bros	O
and	O
Digital	O
Content	B-Application
Protection	I-Application
,	O
LLC	O
(	O
DCP	O
,	O
the	O
owners	O
of	O
HDCP	B-Protocol
)	O
filed	O
a	O
lawsuit	O
against	O
LegendSky	O
.	O
</s>
<s>
Nevertheless	O
,	O
the	O
lawsuit	O
was	O
ultimately	O
dropped	O
after	O
LegendSky	O
argued	O
that	O
the	O
device	O
did	O
not	O
"	O
strip	O
"	O
HDCP	B-Protocol
content	B-Application
protection	I-Application
but	O
rather	O
downgraded	O
it	O
to	O
an	O
older	O
version	O
,	O
a	O
measure	O
which	O
is	O
explicitly	O
permitted	O
in	O
DCP	O
's	O
licensing	O
manual	O
.	O
</s>
<s>
HDCP	B-Protocol
can	O
cause	O
problems	O
for	O
users	O
who	O
want	O
to	O
connect	O
multiple	O
screens	O
to	O
a	O
device	O
;	O
for	O
example	O
,	O
a	O
bar	O
with	O
several	O
televisions	O
connected	O
to	O
one	O
satellite	O
receiver	O
or	O
when	O
a	O
user	O
has	O
a	O
closed	O
laptop	O
and	O
uses	O
an	O
external	O
display	O
as	O
the	O
only	O
monitor	O
.	O
</s>
<s>
HDCP	B-Protocol
devices	O
can	O
create	O
multiple	O
keys	O
,	O
allowing	O
each	O
screen	O
to	O
operate	O
,	O
but	O
the	O
number	O
varies	O
from	O
device	O
to	O
device	O
;	O
e.g.	O
,	O
a	O
Dish	O
or	O
Sky	O
satellite	O
receiver	O
can	O
generate	O
16	O
keys	O
.	O
</s>
<s>
The	O
technology	O
sometimes	O
causes	O
handshaking	B-Protocol
problems	O
where	O
devices	O
cannot	O
establish	O
a	O
connection	O
,	O
especially	O
with	O
older	O
high-definition	O
displays	O
.	O
</s>
<s>
Edward	O
Felten	O
wrote	O
"	O
the	O
main	O
practical	O
effect	O
of	O
HDCP	B-Protocol
has	O
been	O
to	O
create	O
one	O
more	O
way	O
in	O
which	O
your	O
electronics	O
could	O
fail	O
to	O
work	O
properly	O
with	O
your	O
TV	O
,	O
"	O
and	O
concluded	O
in	O
the	O
aftermath	O
of	O
the	O
master	O
key	O
fiasco	O
that	O
HDCP	B-Protocol
has	O
been	O
"	O
less	O
a	O
security	O
system	O
than	O
a	O
tool	O
for	O
shaping	O
the	O
consumer	O
electronics	O
market.	O
"	O
</s>
<s>
video	O
games	O
)	O
suffer	O
from	O
control	B-Application
latency	I-Application
,	O
because	O
it	O
requires	O
additional	O
processing	O
for	O
encoding/decoding	O
.	O
</s>
<s>
There	O
is	O
also	O
the	O
problem	O
that	O
all	O
Apple	O
laptop	O
products	O
,	O
presumably	O
in	O
order	O
to	O
reduce	O
switching	O
time	O
,	O
when	O
confronted	O
with	O
an	O
HDCP-compliant	O
sink	O
device	O
,	O
automatically	O
enable	O
HDCP	B-Protocol
encryption	O
from	O
the	O
HDMI	B-Protocol
/	O
Mini	O
DisplayPort	B-Protocol
/	O
USB-C	O
connector	O
port	O
.	O
</s>
<s>
This	O
is	O
a	O
problem	O
if	O
the	O
user	O
wishes	O
to	O
use	O
recording	O
or	O
videoconferencing	O
facilities	O
further	O
down	O
the	O
chain	O
,	O
because	O
these	O
devices	O
most	O
often	O
do	O
not	O
decrypt	O
HDCP-enabled	O
content	O
(	O
since	O
HDCP	B-Protocol
is	O
meant	O
to	O
avoid	O
direct	O
copying	O
of	O
content	O
,	O
and	O
such	O
devices	O
could	O
conceivably	O
do	O
exactly	O
that	O
)	O
.	O
</s>
<s>
This	O
applies	O
even	O
if	O
the	O
output	O
is	O
not	O
HDCP-requiring	O
content	O
,	O
like	O
a	O
PowerPoint	B-Application
presentation	O
or	O
merely	O
the	O
device	O
's	O
UI	O
.	O
</s>
<s>
Some	O
sink	O
devices	O
have	O
the	O
ability	O
to	O
disable	O
their	O
HDCP	B-Protocol
reporting	O
entirely	O
,	O
however	O
,	O
preventing	O
this	O
issue	O
from	O
blocking	O
content	O
to	O
videoconferencing	O
or	O
recording	O
.	O
</s>
<s>
However	O
,	O
HDCP	B-Protocol
content	O
will	O
then	O
refuse	O
to	O
play	O
on	O
many	O
source	O
devices	O
if	O
this	O
is	O
disabled	O
while	O
the	O
sink	O
device	O
is	O
connected	O
.	O
</s>
<s>
When	O
connecting	O
a	O
HDCP	B-Protocol
2.2	O
source	O
device	O
through	O
compatible	O
distribution	O
to	O
a	O
video	O
wall	O
made	O
of	O
multiple	O
legacy	O
displays	O
the	O
ability	O
to	O
display	O
an	O
image	O
can	O
not	O
be	O
guaranteed	O
.	O
</s>
<s>
Type	O
1	O
is	O
a	O
flag	O
preventing	O
content	O
from	O
going	O
to	O
v1.x	O
HDCP	B-Protocol
.	O
</s>
<s>
The	O
2.x	O
version	O
of	O
HDCP	B-Protocol
is	O
not	O
a	O
continuation	O
of	O
HDCPv1	O
,	O
and	O
is	O
rather	O
a	O
completely	O
different	O
link	O
protection	O
.	O
</s>
<s>
Version	O
2.x	O
employs	O
industry-standard	O
encryption	O
algorithms	O
,	O
such	O
as	O
128-bit	O
AES	B-Algorithm
with	O
3072	O
or	O
1024-bit	O
RSA	B-Architecture
public	O
key	O
and	O
256-bit	O
HMAC-SHA256	B-Algorithm
hash	O
function	O
.	O
</s>
<s>
While	O
all	O
of	O
the	O
HDCP	B-Protocol
v1.x	O
specifications	O
support	O
backward	O
compatibility	O
to	O
previous	O
versions	O
of	O
the	O
specification	O
,	O
HDCPv2	O
devices	O
may	O
interface	O
with	O
HDCPv1	O
hardware	O
only	O
by	O
natively	O
supporting	O
HDCPv1	O
,	O
or	O
by	O
using	O
a	O
dedicated	O
converter	O
device	O
.	O
</s>
<s>
HDCP	B-Protocol
2.x	O
features	O
a	O
new	O
authentication	O
protocol	O
,	O
and	O
a	O
locality	O
check	O
to	O
ensure	O
the	O
receiver	O
is	O
relatively	O
close	O
(	O
it	O
must	O
respond	O
to	O
the	O
locality	O
check	O
within	O
7	O
ms	O
on	O
a	O
normal	O
DVI/HDMI	O
link	O
)	O
.	O
</s>
<s>
There	O
are	O
still	O
a	O
few	O
commonalities	O
between	O
HDCP	B-Protocol
v2	O
and	O
v1	O
.	O
</s>
