<s>
Rooting	B-Application
is	O
the	O
process	O
by	O
which	O
users	O
of	O
Android	B-Application
devices	O
can	O
attain	O
privileged	O
control	O
(	O
known	O
as	O
root	B-Application
access	I-Application
)	O
over	O
various	O
subsystems	O
of	O
the	O
device	O
,	O
usually	O
smartphones	O
.	O
</s>
<s>
Because	O
Android	B-Application
is	O
based	O
on	O
a	O
modified	O
version	O
of	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
rooting	B-Application
an	O
Android	B-Application
device	O
gives	O
similar	O
access	O
to	O
administrative	O
(	O
superuser	B-Application
)	O
permissions	O
as	O
on	O
Linux	B-Application
or	O
any	O
other	O
Unix-like	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
such	O
as	O
FreeBSD	B-Operating_System
or	O
macOS	B-Application
.	O
</s>
<s>
Rooting	B-Application
is	O
often	O
performed	O
with	O
the	O
goal	O
of	O
overcoming	O
limitations	O
that	O
carriers	O
and	O
hardware	O
manufacturers	O
put	O
on	O
some	O
devices	O
.	O
</s>
<s>
Thus	O
,	O
rooting	B-Application
gives	O
the	O
ability	O
(	O
or	O
permission	O
)	O
to	O
alter	O
or	O
replace	O
system	O
applications	B-Application
and	O
settings	O
,	O
run	O
specialized	O
applications	B-Application
(	O
"	O
apps	O
"	O
)	O
that	O
require	O
administrator-level	O
permissions	O
or	O
perform	O
other	O
operations	O
that	O
are	O
otherwise	O
inaccessible	O
to	O
a	O
normal	O
Android	B-Application
user	O
.	O
</s>
<s>
On	O
some	O
devices	O
,	O
rooting	B-Application
can	O
also	O
facilitate	O
the	O
complete	O
removal	O
and	O
replacement	O
of	O
the	O
device	O
's	O
operating	O
system	O
,	O
usually	O
with	O
a	O
more	O
recent	O
release	O
of	O
its	O
current	O
operating	O
system	O
.	O
</s>
<s>
Root	B-Application
access	I-Application
is	O
sometimes	O
compared	O
to	O
jailbreaking	B-Application
devices	O
running	O
the	O
Apple	O
iOS	B-Application
operating	O
system	O
.	O
</s>
<s>
However	O
,	O
these	O
are	O
different	O
concepts	O
:	O
Jailbreaking	B-Application
is	O
the	O
bypass	O
of	O
several	O
types	O
of	O
Apple	O
prohibitions	O
for	O
the	O
end	O
user	O
,	O
including	O
modifying	O
the	O
operating	O
system	O
(	O
enforced	O
by	O
a	O
"	O
locked	O
bootloader	B-Application
"	O
)	O
,	O
installing	O
non-officially	O
approved	O
(	O
not	O
available	O
on	O
the	O
App	B-Application
Store	I-Application
)	O
applications	B-Application
via	O
sideloading	B-Protocol
,	O
and	O
granting	O
the	O
user	O
elevated	O
administration-level	O
privileges	O
(	O
rooting	B-Application
)	O
.	O
</s>
<s>
Many	O
vendors	O
such	O
as	O
HTC	B-Application
,	O
Sony	O
,	O
OnePlus	O
,	O
Asus	O
,	O
Xiaomi	O
and	O
Google	B-Application
explicitly	O
provide	O
the	O
ability	O
to	O
unlock	O
devices	O
,	O
and	O
even	O
replace	O
the	O
operating	O
system	O
entirely	O
.	O
</s>
<s>
Similarly	O
,	O
the	O
ability	O
to	O
sideload	B-Protocol
applications	B-Application
is	O
typically	O
permissible	O
on	O
Android	B-Application
devices	O
without	O
root	O
permissions	O
.	O
</s>
<s>
Thus	O
,	O
it	O
is	O
primarily	O
the	O
third	O
aspect	O
of	O
iOS	B-Application
jailbreaking	I-Application
(	O
giving	O
users	O
administrative	B-Application
privileges	I-Application
)	O
that	O
most	O
directly	O
correlates	O
to	O
Android	B-Application
rooting	I-Application
.	O
</s>
<s>
Rooting	B-Application
is	O
distinct	O
from	O
SIM	O
unlocking	O
and	O
bootloader	B-Application
unlocking	I-Application
.	O
</s>
<s>
The	O
former	O
allows	O
removing	O
the	O
SIM	O
card	O
lock	O
on	O
a	O
phone	O
,	O
while	O
the	O
latter	O
allows	O
rewriting	O
the	O
phone	O
's	O
boot	O
partition	B-Application
(	O
for	O
example	O
,	O
to	O
install	O
or	O
replace	O
the	O
operating	O
system	O
)	O
.	O
</s>
<s>
Rooting	B-Application
lets	O
all	O
user-installed	O
applications	B-Application
run	O
privileged	O
commands	O
typically	O
unavailable	O
to	O
the	O
devices	O
in	O
the	O
stock	O
configuration	O
.	O
</s>
<s>
Rooting	B-Application
is	O
required	O
for	O
more	O
advanced	O
and	O
potentially	O
dangerous	O
operations	O
including	O
modifying	O
or	O
deleting	O
system	O
files	O
,	O
removing	O
pre-installed	B-Application
applications	I-Application
,	O
and	O
low-level	O
access	O
to	O
the	O
hardware	O
itself	O
(	O
rebooting	O
,	O
controlling	O
status	O
lights	O
,	O
or	O
recalibrating	O
touch	O
inputs	O
.	O
)	O
</s>
<s>
A	O
typical	O
rooting	B-Application
installation	O
also	O
installs	O
the	O
Superuser	B-Application
application	O
,	O
which	O
supervises	O
applications	B-Application
that	O
are	O
granted	O
root	O
or	O
superuser	B-Application
rights	O
by	O
requesting	O
approval	O
from	O
the	O
user	O
before	O
granting	O
said	O
permissions	O
.	O
</s>
<s>
A	O
secondary	O
operation	O
,	O
unlocking	O
the	O
device	O
's	O
bootloader	B-Application
verification	O
,	O
is	O
required	O
to	O
remove	O
or	O
replace	O
the	O
installed	O
operating	O
system	O
.	O
</s>
<s>
In	O
contrast	O
to	O
iOS	B-Application
jailbreaking	I-Application
,	O
rooting	B-Application
is	O
not	O
needed	O
to	O
run	O
applications	B-Application
distributed	O
outside	O
of	O
the	B-Application
Google	I-Application
Play	O
Store	O
,	O
sometimes	O
called	O
sideloading	B-Protocol
.	O
</s>
<s>
The	O
Android	B-Application
OS	I-Application
supports	O
this	O
feature	O
natively	O
in	O
two	O
ways	O
:	O
through	O
the	O
"	O
Unknown	O
sources	O
"	O
option	O
in	O
the	O
Settings	O
menu	O
and	O
through	O
the	O
Android	B-Application
Debug	I-Application
Bridge	I-Application
.	O
</s>
<s>
However	O
,	O
some	O
US	O
carriers	O
,	O
including	O
AT&T	O
,	O
prevented	O
the	O
installation	O
of	O
applications	B-Application
not	O
on	O
the	O
Play	O
Store	O
in	O
firmware	B-Application
,	O
although	O
several	O
devices	O
are	O
not	O
subject	O
to	O
this	O
rule	O
,	O
including	O
the	O
Samsung	B-Application
Infuse	O
4G	O
;	O
AT&T	O
lifted	O
the	O
restriction	O
on	O
most	O
devices	O
by	O
the	O
middle	O
of	O
2011	O
.	O
</s>
<s>
,	O
the	O
Amazon	B-Application
Kindle	I-Application
Fire	I-Application
defaults	O
to	O
the	O
Amazon	B-Application
Appstore	B-Application
instead	O
of	O
Google	B-Application
Play	I-Application
,	O
though	O
like	O
most	O
other	O
Android	B-Application
devices	O
,	O
Kindle	B-Application
Fire	I-Application
allows	O
sideloading	B-Protocol
of	O
applications	B-Application
from	O
unknown	O
sources	O
,	O
and	O
the	O
"	O
easy	O
installer	O
"	O
application	O
on	O
the	O
Amazon	B-Application
Appstore	B-Application
makes	O
this	O
easy	O
.	O
</s>
<s>
Other	O
vendors	O
of	O
Android	B-Application
devices	O
may	O
look	O
to	O
other	O
sources	O
in	O
the	O
future	O
.	O
</s>
<s>
Access	O
to	O
alternate	O
apps	O
may	O
require	O
rooting	B-Application
but	O
rooting	B-Application
is	O
not	O
always	O
necessary	O
.	O
</s>
<s>
Rooting	B-Application
an	O
Android	B-Application
phone	I-Application
lets	O
the	O
owner	O
add	O
,	O
edit	O
or	O
delete	O
system	O
files	O
,	O
which	O
in	O
turn	O
lets	O
them	O
perform	O
various	O
tweaks	O
and	O
use	O
apps	O
that	O
require	O
root	B-Application
access	I-Application
.	O
</s>
<s>
Advantages	O
of	O
rooting	B-Application
include	O
the	O
possibility	O
for	O
complete	O
control	O
over	O
the	O
appearance	O
,	O
feel	O
,	O
and	O
behaviour	O
of	O
the	O
device	O
.	O
</s>
<s>
As	O
a	O
superuser	B-Application
has	O
access	O
to	O
the	O
device	O
's	O
system	O
files	O
,	O
all	O
aspects	O
of	O
the	O
operating	O
system	O
can	O
be	O
customized	O
with	O
the	O
only	O
real	O
limitation	O
being	O
the	O
level	O
of	O
coding	O
expertise	O
.	O
</s>
<s>
Support	O
for	O
theming	B-Application
,	O
allowing	O
everything	O
to	O
be	O
visually	O
changed	O
from	O
the	O
color	O
and	O
type	O
of	O
the	O
battery	O
status	O
indicator	O
to	O
the	O
boot	B-Operating_System
animation	I-Operating_System
that	O
appears	O
while	O
the	O
device	O
is	O
booting	O
,	O
the	O
status	O
bar	O
,	O
control	O
menu	O
,	O
virtual	O
on-screen	O
navigation	O
buttons	O
,	O
and	O
more	O
.	O
</s>
<s>
Full	O
control	O
of	O
the	O
kernel	B-Operating_System
,	O
which	O
,	O
for	O
example	O
,	O
allows	O
overclocking	B-Application
and	O
underclocking	O
the	O
CPU	O
and	O
GPU	O
.	O
</s>
<s>
Full	O
application	O
control	O
,	O
including	O
the	O
ability	O
to	O
fully	O
back	B-Protocol
up	I-Protocol
,	O
restore	O
,	O
or	O
batch-edit	O
applications	B-Application
,	O
or	O
to	O
remove	O
bloatware	O
that	O
comes	O
pre-installed	B-Application
on	O
some	O
phones	O
.	O
</s>
<s>
Custom	O
automated	O
system-level	O
processes	O
through	O
the	O
use	O
of	O
third-party	O
applications	B-Application
.	O
</s>
<s>
Ability	O
to	O
install	O
software	O
(	O
such	O
as	O
Xposed	O
,	O
Magisk	B-Application
,	O
SuperSU	B-Application
,	O
BusyBox	B-Application
,	O
etc	O
.	O
)	O
</s>
<s>
that	O
allows	O
additional	O
levels	O
of	O
control	O
on	O
a	O
rooted	O
device	O
or	O
management	O
of	O
root	B-Application
access	I-Application
.	O
</s>
<s>
Access	O
to	O
more	O
Unix	B-Application
shell	I-Application
commands	O
,	O
both	O
standalone	O
and	O
through	O
Android	B-Application
Debug	I-Application
Bridge	I-Application
.	O
</s>
<s>
Ability	O
to	O
bypass	O
restrictions	O
by	O
vendors	O
or	O
Google	B-Application
,	O
such	O
as	O
scoped	O
storage	O
,	O
which	O
compromised	O
file	O
system	O
access	O
and	O
compatibility	O
to	O
established	O
third-party	O
mobile	B-Application
applications	I-Application
such	O
as	O
file	B-Application
managers	I-Application
.	O
</s>
<s>
Ability	O
to	O
downgrade	O
applications	B-Application
directly	O
,	O
without	O
uninstallation	O
which	O
involves	O
deleting	O
their	O
user	O
data	O
.	O
</s>
<s>
APIs	B-Application
may	O
vary	O
per	O
vendor	O
.	O
</s>
<s>
For	O
example	O
,	O
on	O
Samsung	B-Operating_System
Galaxy	I-Operating_System
devices	O
,	O
this	O
is	O
done	O
by	O
applying	O
a	O
value	O
to	O
the	O
/sys/devices/platform/sec-battery/power_supply/battery/siop_level	O
system	B-Application
file	I-Application
,	O
where	O
100	O
represents	O
the	O
highest	O
technically	O
supported	O
charging	O
rate	O
.	O
</s>
<s>
Some	O
disadvantages	O
of	O
rooting	B-Application
include	O
:	O
</s>
<s>
On	O
certain	O
brands	O
such	O
as	O
Samsung	B-Application
and	O
Motorola	O
,	O
rooting	B-Application
can	O
void	O
one	O
's	O
warranty	O
.	O
</s>
<s>
If	O
used	O
incorrectly	O
,	O
rooting	B-Application
can	O
cause	O
stability	O
issues	O
with	O
the	O
software	O
or	O
hardware	O
.	O
</s>
<s>
Certain	O
devices	O
,	O
including	O
those	O
from	O
Huawei	O
and	O
any	O
brand	O
sold	O
by	O
Verizon	B-Application
lack	O
the	O
ability	O
to	O
get	O
easily	O
rooted	O
,	O
unless	O
a	O
privilege	O
escalation	O
exploit	O
is	O
found	O
in	O
the	O
device	O
's	O
operating	O
system	O
version	O
.	O
</s>
<s>
Rooting	B-Application
allows	O
the	O
user	O
to	O
obtain	O
privileged	O
access	O
to	O
a	O
phone	O
.	O
</s>
<s>
It	O
does	O
not	O
allow	O
a	O
user	O
to	O
install	O
a	O
new	O
OS	O
(	O
custom	O
firmware	B-Application
or	O
custom	B-Application
ROM	I-Application
)	O
or	O
recovery	O
image	O
,	O
and	O
it	O
does	O
n't	O
allow	O
a	O
phone	O
that	O
locked	O
to	O
a	O
certain	O
carrier	O
to	O
be	O
used	O
on	O
another	O
one	O
.	O
</s>
<s>
Bootloader	B-Application
unlocking	I-Application
is	O
sometimes	O
a	O
first	O
step	O
used	O
to	O
root	O
the	O
device	O
;	O
however	O
,	O
it	O
is	O
not	O
the	O
same	O
as	O
rooting	B-Application
the	O
device	O
.	O
</s>
<s>
Most	O
devices	O
come	O
with	O
a	O
locked	O
bootloader	B-Application
,	O
which	O
prevents	O
users	O
from	O
installing	O
a	O
new	O
bootloader	B-Application
.	O
</s>
<s>
The	O
bootloader	B-Application
runs	O
on	O
device	O
start-up	O
and	O
is	O
in	O
charge	O
of	O
loading	O
the	O
operating	O
system	O
on	O
the	O
phone	O
.	O
</s>
<s>
Nonetheless	O
,	O
people	O
still	O
perform	O
this	O
operation	O
,	O
as	O
unlocking	O
the	O
bootloader	B-Application
allows	O
users	O
to	O
install	O
custom	O
ROMs	O
.	O
</s>
<s>
Not	O
all	O
devices	O
can	O
be	O
bootloader	B-Application
unlocked	O
.	O
</s>
<s>
The	O
process	O
of	O
unlocking	O
the	O
bootloader	B-Application
might	O
involve	O
a	O
factory	O
reset	O
,	O
erasing	O
all	O
user	O
data	O
,	O
third-party	O
applications	B-Application
,	O
and	O
configuration	O
.	O
</s>
<s>
Some	O
rooting	B-Application
methods	O
involve	O
the	O
use	O
of	O
a	O
command	B-Application
prompt	I-Application
and	O
a	O
development	O
interface	O
called	O
the	O
Android	B-Application
Debug	I-Application
Bridge	I-Application
(	O
also	O
known	O
as	O
ADB	O
)	O
,	O
while	O
other	O
methods	O
may	O
use	O
existing	O
vulnerabilities	O
in	O
devices	O
.	O
</s>
<s>
Due	O
to	O
similarly	O
modeled	O
devices	O
often	O
having	O
a	O
multitude	O
of	O
changes	O
,	O
rooting	B-Application
methods	O
for	O
one	O
device	O
when	O
used	O
for	O
a	O
different	O
variant	O
can	O
result	O
in	O
bricking	O
the	O
device	O
.	O
</s>
<s>
"	O
Systemless	O
root	O
"	O
is	O
a	O
variant	O
of	O
rooting	B-Application
in	O
which	O
the	O
underlying	O
device	O
file	O
system	O
is	O
not	O
modified	O
.	O
</s>
<s>
Systemless	O
root	O
uses	O
various	O
techniques	O
to	O
gain	O
root	B-Application
access	I-Application
without	O
modifying	O
the	O
system	O
partition	B-Application
of	O
a	O
device	O
.	O
</s>
<s>
Some	O
root	O
applications	B-Application
may	O
include	O
a	O
"	O
hiding	O
"	O
function	O
,	O
which	O
makes	O
attempts	O
to	O
mask	O
the	O
effects	O
and	O
results	O
of	O
rooting	B-Application
,	O
often	O
by	O
whitelisting	O
certain	O
applications	B-Application
for	O
the	O
root	O
or	O
blocking	O
access	O
to	O
affected	O
files	O
.	O
</s>
<s>
Systemless	O
rooting	B-Application
has	O
the	O
advantage	O
of	O
not	O
triggering	O
the	O
software-based	O
version	O
of	O
SafetyNet	B-Application
,	O
an	O
Android	B-Application
feature	O
that	O
works	O
by	O
monitoring	O
changes	O
to	O
system	O
files	O
and	O
is	O
used	O
by	O
applications	B-Application
such	O
as	O
Google	B-Application
Pay	O
to	O
detect	O
whether	O
a	O
device	O
has	O
been	O
tampered	O
with	O
such	O
as	O
by	O
rooting	B-Application
.	O
</s>
<s>
However	O
,	O
hardware-backed	O
SafetyNet	B-Application
versions	O
may	O
be	O
triggered	O
by	O
systemless	O
rooting	B-Application
,	O
as	O
well	O
as	O
in	O
unrooted	O
devices	O
shipped	O
without	O
Google	B-Application
Mobile	I-Application
Services	I-Application
(	O
GMS	O
)	O
.	O
</s>
<s>
The	O
distinction	O
between	O
"	O
soft	O
rooting	B-Application
"	O
through	O
a	O
security	O
vulnerability	O
and	O
"	O
hard-rooting	O
"	O
by	O
flashing	O
a	O
su	B-Device
binary	B-Application
executable	I-Application
varies	O
from	O
exploit	O
to	O
exploit	O
,	O
and	O
manufacturer	O
to	O
manufacturer	O
.	O
</s>
<s>
Soft-rooting	O
requires	O
that	O
a	O
device	O
be	O
vulnerable	O
to	O
privilege	O
escalation	O
,	O
or	O
replacing	O
executable	B-Application
binaries	I-Application
.	O
</s>
<s>
Hard-rooting	O
is	O
supported	O
by	O
the	O
manufacturer	O
,	O
and	O
it	O
generally	O
only	O
exposed	O
for	O
devices	O
the	O
manufacturer	O
allows	O
.	O
</s>
<s>
The	O
process	O
of	O
rooting	B-Application
varies	O
widely	O
by	O
manufacturer	O
and	O
device	O
but	O
sometimes	O
includes	O
exploiting	O
one	O
or	O
more	O
security	O
bugs	O
in	O
the	O
firmware	B-Application
of	O
(	O
i.e.	O
,	O
in	O
the	O
version	O
of	O
the	O
Android	B-Application
OS	I-Application
installed	O
on	O
)	O
the	O
device	O
.	O
</s>
<s>
Once	O
an	O
exploit	O
is	O
discovered	O
,	O
a	O
custom	O
recovery	O
image	O
that	O
will	O
skip	O
the	O
digital	O
signature	O
check	O
of	O
firmware	B-Application
updates	O
can	O
be	O
flashed	O
.	O
</s>
<s>
Then	O
a	O
modified	O
firmware	B-Application
update	O
that	O
typically	O
includes	O
the	O
utilities	O
needed	O
to	O
run	O
apps	O
as	O
root	O
can	O
be	O
installed	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
su	B-Device
binary	B-Application
(	O
such	O
as	O
an	O
open-source	O
one	O
paired	O
with	O
the	O
Superuser	B-Application
or	O
SuperSU	B-Application
application	O
)	O
can	O
be	O
copied	O
to	O
a	O
location	O
in	O
the	O
current	O
process	O
 '	O
PATH	B-Application
(	O
e.g.	O
,	O
/system/xbin/	O
)	O
and	O
granted	O
executable	B-Application
permissions	O
with	O
the	O
chmod	B-Application
command	O
.	O
</s>
<s>
A	O
third-party	O
supervisor	O
application	O
,	O
like	O
Superuser	B-Application
or	O
SuperSU	B-Application
,	O
can	O
then	O
regulate	O
and	O
log	O
elevated	O
permission	O
requests	O
from	O
other	O
applications	B-Application
.	O
</s>
<s>
Many	O
guides	O
,	O
tutorials	O
,	O
and	O
automatic	O
processes	O
exist	O
for	O
popular	O
Android	B-Application
devices	O
facilitating	O
a	O
fast	O
and	O
easy	O
rooting	B-Application
process	O
.	O
</s>
<s>
The	O
process	O
of	O
rooting	B-Application
a	O
device	O
may	O
be	O
simple	O
or	O
complex	O
,	O
and	O
it	O
even	O
may	O
depend	O
upon	O
serendipity	O
.	O
</s>
<s>
For	O
example	O
,	O
shortly	O
after	O
the	O
release	O
of	O
the	O
HTC	B-Application
Dream	O
(	O
HTC	B-Application
G1	O
)	O
,	O
it	O
was	O
discovered	O
that	O
anything	O
typed	O
using	O
the	O
keyboard	O
was	O
being	O
interpreted	O
as	O
a	O
command	O
in	O
a	O
privileged	O
(	O
root	O
)	O
shell	O
.	O
</s>
<s>
Although	O
Google	B-Application
quickly	O
released	O
a	O
patch	O
to	O
fix	O
this	O
,	O
a	O
signed	O
image	O
of	O
the	O
old	O
firmware	B-Application
leaked	O
,	O
which	O
gave	O
users	O
the	O
ability	O
to	O
downgrade	O
and	O
use	O
the	O
original	O
exploit	O
to	O
gain	O
root	B-Application
access	I-Application
.	O
</s>
<s>
Installable	O
apps	O
have	O
managed	O
to	O
unlock	O
immediate	O
root	B-Application
access	I-Application
on	O
some	O
early	O
2010s	O
Samsung	B-Application
smartphones	O
.	O
</s>
<s>
This	O
has	O
also	O
been	O
referred	O
to	O
as	O
"	O
one-click	O
rooting	B-Application
"	O
.	O
</s>
<s>
A	O
security	O
researcher	O
,	O
Grant	O
Hernandez	O
,	O
demonstrated	O
a	O
use-after-free	O
exploit	O
in	O
Binder	O
,	O
Android	B-Application
's	O
IPC	O
framework	O
,	O
to	O
gain	O
root	B-Application
privileges	I-Application
.	O
</s>
<s>
Some	O
manufacturers	O
,	O
including	O
Xiaomi	O
,	O
OnePlus	O
,	O
and	O
Motorola	O
,	O
provide	O
official	O
support	O
for	O
unlocking	O
the	O
bootloader	B-Application
,	O
allowing	O
for	O
rooting	B-Application
without	O
exploiting	O
a	O
vulnerability	O
.	O
</s>
<s>
However	O
,	O
the	O
support	O
may	O
be	O
limited	O
only	O
to	O
certain	O
phones	O
–	O
for	O
example	O
,	O
LG	O
released	O
its	O
bootloader	B-Application
unlock	I-Application
tool	O
only	O
for	O
certain	O
models	O
of	O
its	O
phones	O
.	O
</s>
<s>
Also	O
,	O
a	O
manufacturer	O
could	O
discontinue	O
bootloader	B-Application
unlocking	I-Application
support	O
,	O
as	O
was	O
the	O
case	O
with	O
LG	O
and	O
Huawei	O
.	O
</s>
<s>
The	B-Application
Google	I-Application
Nexus	B-Device
and	O
Pixel	B-Device
line	O
of	O
devices	O
can	O
have	O
their	O
bootloader	B-Application
unlocked	O
by	O
simply	O
connecting	O
the	O
device	O
to	O
a	O
computer	O
while	O
in	O
bootloader	B-Application
mode	O
and	O
running	O
the	O
Fastboot	B-Application
protocol	O
with	O
the	O
command	O
fastboot	B-Application
oem	B-Application
unlock	I-Application
on	O
older	O
devices	O
,	O
or	O
fastboot	B-Application
flashing	O
unlock	O
on	O
newer	O
devices	O
.	O
</s>
<s>
After	O
a	O
warning	O
is	O
accepted	O
,	O
the	O
bootloader	B-Application
is	O
unlocked	O
,	O
so	O
a	O
new	O
system	O
image	O
can	O
be	O
written	O
directly	O
to	O
flash	O
without	O
the	O
need	O
for	O
an	O
exploit	O
.	O
</s>
<s>
Additionally	O
,	O
Pixel	B-Device
phones	O
sold	O
via	O
certain	O
carriers	O
like	O
Verizon	B-Application
do	O
not	O
support	O
bootloader	B-Application
unlocking	I-Application
,	O
while	O
others	O
such	O
as	O
T-Mobile	O
require	O
the	O
phone	O
to	O
be	O
paid	O
off	O
before	O
the	O
bootloader	B-Application
can	O
be	O
unlocked	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
many	O
manufacturers	O
have	O
tried	O
to	O
make	O
non-rootable	O
phones	O
with	O
more	O
elaborate	O
protections	O
(	O
like	O
the	O
Droid	B-Application
X	I-Application
)	O
,	O
but	O
exploits	O
are	O
usually	O
still	O
found	O
eventually	O
.	O
</s>
<s>
Until	O
2010	O
,	O
tablet	O
and	O
smartphone	O
manufacturers	O
,	O
as	O
well	O
as	O
mobile	O
carriers	O
,	O
were	O
mainly	O
unsupportive	O
of	O
third-party	O
firmware	B-Application
development	O
.	O
</s>
<s>
Moreover	O
,	O
firmware	B-Application
such	O
as	O
OmniROM	B-Application
and	O
CyanogenMod	B-Application
sometimes	O
offer	O
features	O
for	O
which	O
carriers	O
would	O
otherwise	O
charge	O
a	O
premium	O
,	O
such	O
as	O
tethering	O
.	O
</s>
<s>
Due	O
to	O
that	O
,	O
technical	O
obstacles	O
such	O
as	O
locked	O
bootloaders	B-Application
and	O
restricted	O
access	O
to	O
root	O
permissions	O
have	O
commonly	O
been	O
introduced	O
in	O
many	O
devices	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
late	O
December	O
2011	O
,	O
Barnes	O
&	O
Noble	O
and	O
Amazon.com,	B-Application
Inc	I-Application
.	I-Application
began	O
pushing	O
automatic	O
,	O
over-the-air	O
firmware	B-Application
updates	O
,	O
1.4.1	O
to	O
Nook	B-Application
Tablets	I-Application
and	O
6.2.1	O
to	O
Kindle	B-Application
Fires	I-Application
,	O
that	O
removed	O
one	O
method	O
to	O
gain	O
root	B-Application
access	I-Application
to	O
the	O
devices	O
.	O
</s>
<s>
The	O
Nook	B-Application
Tablet	I-Application
1.4.1	O
update	O
also	O
removed	O
users	O
 '	O
ability	O
to	O
sideload	B-Protocol
apps	O
from	O
sources	O
other	O
than	O
the	O
official	O
Barnes	O
&	O
Noble	O
app	B-Application
store	I-Application
(	O
without	O
modding	B-Device
)	O
.	O
</s>
<s>
However	O
,	O
as	O
community-developed	O
software	O
began	O
to	O
grow	O
popular	O
in	O
the	O
late	O
2009	O
to	O
early	O
2010	O
,	O
and	O
following	O
a	O
statement	O
by	O
the	O
Copyright	O
Office	O
and	O
Librarian	O
of	O
Congress	O
(	O
US	O
)	O
allowing	O
the	O
use	O
of	O
"	O
jailbroken	B-Application
"	O
mobile	O
devices	O
,	O
manufacturers	O
and	O
carriers	O
have	O
softened	O
their	O
position	O
regarding	O
CyanogenMod	B-Application
and	O
other	O
unofficial	O
firmware	B-Application
distributions	O
.	O
</s>
<s>
Some	O
manufacturers	O
,	O
including	O
HTC	B-Application
,	O
Samsung	B-Application
,	O
Motorola	O
and	O
Sony	O
Mobile	O
Communications	O
,	O
actively	O
provide	O
support	O
and	O
encourage	O
development	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
need	O
to	O
circumvent	O
hardware	O
restrictions	O
to	O
install	O
unofficial	O
firmware	B-Application
lessened	O
as	O
an	O
increasing	O
number	O
of	O
devices	O
shipped	O
with	O
unlocked	O
or	O
unlockable	O
bootloaders	B-Application
,	O
similar	O
to	O
the	O
Nexus	B-Device
and	O
Pixel	B-Device
series	O
of	O
phones	O
.	O
</s>
<s>
Device	O
manufacturer	O
HTC	B-Application
has	O
announced	O
that	O
it	O
will	O
support	O
aftermarket	O
software	O
developers	O
by	O
making	O
the	O
bootloaders	B-Application
of	O
all	O
new	O
devices	O
unlockable	O
.	O
</s>
<s>
However	O
,	O
carriers	O
,	O
such	O
as	O
Verizon	B-Application
and	O
more	O
recently	O
AT&T	O
,	O
have	O
continuously	O
blocked	O
OEMs	O
from	O
releasing	O
retail	O
devices	O
with	O
unlocked	B-Application
bootloaders	I-Application
,	O
opting	O
instead	O
for	O
"	O
developer	O
edition	O
"	O
devices	O
that	O
are	O
only	O
sold	O
unsubsidized	O
and	O
off-contract	O
.	O
</s>
<s>
These	O
are	O
similar	O
in	O
practice	O
to	O
Nexus	B-Device
devices	O
,	O
but	O
for	O
a	O
premium	O
and	O
with	O
no	O
contract	O
discounts	O
.	O
</s>
<s>
More	O
recently	O
,	O
since	O
2019	O
,	O
AT&T	O
has	O
allowed	O
Pixel	B-Device
devices	O
to	O
have	O
unlockable	O
bootloaders	B-Application
once	O
the	O
device	O
is	O
paid	O
off	O
.	O
</s>
<s>
In	O
2014	O
,	O
Samsung	B-Application
released	O
a	O
security	O
feature	O
called	O
Knox	B-Application
,	O
which	O
verifies	O
whether	O
system	O
and	O
boot	O
files	O
were	O
modified	O
.	O
</s>
<s>
If	O
custom	O
firmware	B-Application
was	O
flashed	O
,	O
the	O
eFuse	O
is	O
set	O
to	O
0x1	O
,	O
permanently	O
voiding	O
the	O
warranty	O
and	O
disabling	O
Knox-enabled	O
features	O
.	O
</s>
<s>
International	O
treaties	O
have	O
influenced	O
the	O
development	O
of	O
laws	O
affecting	O
rooting	B-Application
.	O
</s>
<s>
The	O
American	O
implementation	O
is	O
the	O
Digital	O
Millennium	O
Copyright	O
Act	O
(	O
DMCA	O
)	O
,	O
which	O
includes	O
a	O
process	O
for	O
establishing	O
exemptions	O
for	O
non-copyright-infringing	O
purposes	O
such	O
as	O
rooting	B-Application
.	O
</s>
<s>
In	O
2010	O
,	O
Electronic	O
Frontiers	O
Australia	O
said	O
that	O
it	O
is	O
unclear	O
whether	O
rooting	B-Application
is	O
legal	O
in	O
Australia	O
,	O
and	O
that	O
anti-circumvention	O
laws	O
may	O
apply	O
.	O
</s>
<s>
Rooting	B-Application
a	O
device	O
to	O
run	O
alternative	O
software	O
is	O
a	O
form	O
of	O
circumventing	O
digital	O
locks	O
for	O
the	O
purpose	O
of	O
software	O
interoperability	O
.	O
</s>
<s>
In	O
2011	O
,	O
Michael	O
Geist	O
,	O
a	O
Canadian	O
copyright	O
scholar	O
,	O
cited	O
iPhone	B-Application
jailbreaking	I-Application
as	O
a	O
non-copyright-related	O
activity	O
that	O
overly	O
broad	O
Copyright	O
Act	O
amendments	O
could	O
prohibit	O
.	O
</s>
<s>
Rooting	B-Application
may	O
be	O
a	O
form	O
of	O
circumvention	O
covered	O
by	O
that	O
law	O
,	O
but	O
this	O
has	O
not	O
been	O
tested	O
in	O
court	O
.	O
</s>
<s>
Rooting	B-Application
might	O
be	O
legal	O
in	O
Singapore	O
if	O
done	O
to	O
provide	O
interoperability	O
and	O
not	O
circumvent	O
copyright	O
,	O
but	O
that	O
has	O
not	O
been	O
tested	O
in	O
court	O
.	O
</s>
<s>
Under	O
the	O
Digital	O
Millennium	O
Copyright	O
Act	O
(	O
DMCA	O
)	O
rooting	B-Application
was	O
illegal	O
in	O
the	O
United	O
States	O
except	O
by	O
exemption	O
.	O
</s>
<s>
Copyright	O
Office	O
explicitly	O
recognized	O
an	O
exemption	O
to	O
the	O
DMCA	O
to	O
permit	O
rooting	B-Application
.	O
</s>
<s>
In	O
their	O
ruling	O
,	O
the	O
Library	O
of	O
Congress	O
affirmed	O
on	O
July	O
26	O
,	O
2010	O
,	O
that	O
rooting	B-Application
is	O
exempt	O
from	O
DMCA	O
rules	O
with	O
respect	O
to	O
circumventing	O
digital	O
locks	O
.	O
</s>
<s>
The	O
rooting	B-Application
of	O
smartphones	O
continues	O
to	O
be	O
legal	O
"	O
where	O
circumvention	O
is	O
accomplished	O
for	O
the	O
sole	O
purpose	O
of	O
enabling	O
interoperability	O
of	O
[	O
lawfully	O
obtained	O
software ]	O
applications	B-Application
with	O
computer	O
programs	O
on	O
the	O
telephone	O
handset	O
"	O
.	O
</s>
<s>
Tim	O
Wu	O
,	O
a	O
professor	O
at	O
Columbia	O
Law	O
School	O
,	O
argued	O
in	O
2007	O
that	O
jailbreaking	B-Application
is	O
"	O
legal	O
,	O
ethical	O
,	O
and	O
just	O
plain	O
fun	O
"	O
.	O
</s>
<s>
It	O
is	O
still	O
possible	O
to	O
employ	O
technical	O
countermeasures	O
to	O
prevent	O
rooting	B-Application
or	O
prevent	O
rooted	O
phones	O
from	O
functioning	O
.	O
</s>
<s>
It	O
is	O
also	O
unclear	O
whether	O
it	O
is	O
legal	O
to	O
traffic	O
in	O
the	O
tools	O
used	O
to	O
make	O
rooting	B-Application
easy	O
.	O
</s>
