<s>
The	O
zero	O
trust	O
security	O
model	O
,	O
also	O
known	O
as	O
zero	O
trust	O
architecture	O
(	O
ZTA	O
)	O
,	O
zero	O
trust	O
network	O
architecture	O
or	O
zero	O
trust	O
network	O
access	O
(	O
ZTNA	O
)	O
,	O
and	O
sometimes	O
known	O
as	O
perimeterless	O
security	O
,	O
describes	O
an	O
approach	O
to	O
the	O
design	O
and	O
implementation	O
of	O
IT	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
The	O
main	O
concept	O
behind	O
the	O
zero	O
trust	O
security	O
model	O
is	O
"	O
never	O
trust	O
,	O
always	O
verify	O
,	O
”	O
which	O
means	O
that	O
devices	O
should	O
not	O
be	O
trusted	O
by	O
default	O
,	O
even	O
if	O
they	O
are	O
connected	O
to	O
a	O
permissioned	O
network	O
such	O
as	O
a	O
corporate	O
LAN	B-General_Concept
and	O
even	O
if	O
they	O
were	O
previously	O
verified	O
.	O
</s>
<s>
Most	O
modern	O
corporate	O
networks	O
consist	O
of	O
many	O
interconnected	O
zones	O
,	O
cloud	B-Architecture
services	I-Architecture
and	O
infrastructure	O
,	O
connections	O
to	O
remote	O
and	O
mobile	O
environments	O
,	O
and	O
connections	O
to	O
non-conventional	O
IT	O
,	O
such	O
as	O
IoT	B-Operating_System
devices	O
.	O
</s>
<s>
The	O
reasoning	O
for	O
zero	O
trust	O
is	O
that	O
the	O
traditional	O
approach	O
—	O
trusting	O
devices	O
within	O
a	O
notional	O
"	O
corporate	O
perimeter	O
"	O
,	O
or	O
devices	O
connected	O
via	O
a	O
VPN	B-Application
—	O
is	O
not	O
relevant	O
in	O
the	O
complex	O
environment	O
of	O
a	O
corporate	O
network	O
.	O
</s>
<s>
This	O
brings	O
about	O
zero	O
trust	O
data	B-General_Concept
security	I-General_Concept
where	O
every	O
request	O
to	O
access	O
the	O
data	O
needs	O
to	O
be	O
authenticated	O
dynamically	O
and	O
ensure	O
least	O
privileged	O
access	O
to	O
resources	O
.	O
</s>
<s>
This	O
zero-trust	O
data	B-General_Concept
security	I-General_Concept
approach	O
can	O
protect	O
access	O
to	O
the	O
data	O
.	O
</s>
<s>
The	O
problems	O
of	O
the	O
'	O
Smartie	B-Language
 '	O
or	O
'	O
M&M	O
 '	O
model	O
of	O
the	O
network	O
was	O
described	O
by	O
a	O
Sun	O
Microsystems	O
engineer	O
in	O
a	O
Network	O
World	O
article	O
in	O
May	O
1994	O
,	O
who	O
described	O
fire	O
walls	O
perimeter	O
defence	O
,	O
as	O
a	O
hard	O
shell	O
around	O
a	O
soft	O
centre	O
,	O
"	O
like	O
a	O
Cadbury	O
Egg	O
”	O
.	O
</s>
<s>
In	O
2003	O
the	O
challenges	O
of	O
defining	O
the	O
perimeter	O
to	O
an	O
organisation	O
's	O
IT	B-General_Concept
systems	I-General_Concept
was	O
highlighted	O
by	O
the	O
Jericho	O
Forum	O
of	O
this	O
year	O
,	O
discussing	O
the	O
trend	O
of	O
what	O
was	O
then	O
coined	O
"	O
de-perimeterisation	O
"	O
.	O
</s>
<s>
In	O
2009	O
,	O
Google	B-Application
implemented	O
a	O
zero	O
trust	O
architecture	O
referred	O
to	O
as	O
BeyondCorp	B-Application
.	O
</s>
<s>
However	O
,	O
it	O
would	O
take	O
almost	O
a	O
decade	O
for	O
zero	O
trust	O
architectures	O
to	O
become	O
prevalent	O
,	O
driven	O
in	O
part	O
by	O
increased	O
adoption	O
of	O
mobile	O
and	O
cloud	B-Architecture
services	I-Architecture
.	O
</s>
<s>
In	O
2019	O
the	O
United	O
Kingdom	O
National	O
Cyber	O
Security	O
Centre	O
(	O
NCSC	O
)	O
recommended	O
that	O
network	O
architects	O
consider	O
a	O
zero	O
trust	O
approach	O
for	O
new	O
IT	O
deployments	O
,	O
particularly	O
where	O
significant	O
use	O
of	O
cloud	B-Architecture
services	I-Architecture
is	O
planned	O
.	O
</s>
