<s>
The	O
zero	B-General_Concept
trust	I-General_Concept
security	I-General_Concept
model	I-General_Concept
,	O
also	O
known	O
as	O
zero	B-General_Concept
trust	I-General_Concept
architecture	I-General_Concept
(	O
ZTA	O
)	O
,	O
zero	B-General_Concept
trust	I-General_Concept
network	O
architecture	O
or	O
zero	B-General_Concept
trust	I-General_Concept
network	O
access	O
(	O
ZTNA	B-General_Concept
)	O
,	O
and	O
sometimes	O
known	O
as	O
perimeterless	B-General_Concept
security	I-General_Concept
,	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	B-General_Concept
trust	I-General_Concept
security	I-General_Concept
model	I-General_Concept
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>
ZTNA	B-General_Concept
is	O
implemented	O
by	O
establishing	O
strong	O
identity	O
verification	O
,	O
validating	O
device	O
compliance	O
prior	O
to	O
granting	O
access	O
,	O
and	O
ensuring	O
least	O
privilege	O
access	O
to	O
only	O
explicitly	O
authorized	O
resources	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	B-General_Concept
trust	I-General_Concept
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>
The	O
zero	B-General_Concept
trust	I-General_Concept
approach	O
advocates	O
mutual	O
authentication	O
,	O
including	O
checking	O
the	O
identity	O
and	O
integrity	O
of	O
devices	O
without	O
respect	O
to	O
location	O
,	O
and	O
providing	O
access	O
to	O
applications	O
and	O
services	O
based	O
on	O
the	O
confidence	O
of	O
device	O
identity	O
and	O
device	O
health	O
in	O
combination	O
with	O
user	O
authentication	O
.	O
</s>
<s>
The	O
principles	O
of	O
zero	B-General_Concept
trust	I-General_Concept
can	O
be	O
applied	O
to	O
data	O
access	O
,	O
and	O
to	O
the	O
management	O
of	O
data	O
.	O
</s>
<s>
This	O
brings	O
about	O
zero	B-General_Concept
trust	I-General_Concept
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>
In	O
April	O
1994	O
,	O
the	O
term	O
"	O
zero	B-General_Concept
trust	I-General_Concept
"	O
was	O
coined	O
by	O
Stephen	O
Paul	O
Marsh	O
in	O
his	O
doctoral	O
thesis	O
on	O
computer	O
security	O
at	O
the	O
University	O
of	O
Stirling	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	B-General_Concept
trust	I-General_Concept
architecture	I-General_Concept
referred	O
to	O
as	O
BeyondCorp	B-Application
.	O
</s>
<s>
In	O
2010	O
the	O
term	O
zero	B-General_Concept
trust	I-General_Concept
model	I-General_Concept
was	O
used	O
by	O
analyst	O
John	O
Kindervag	O
of	O
Forrester	O
Research	O
to	O
denote	O
stricter	O
cybersecurity	O
programs	O
and	O
access	O
control	O
within	O
corporations	O
.	O
</s>
<s>
However	O
,	O
it	O
would	O
take	O
almost	O
a	O
decade	O
for	O
zero	B-General_Concept
trust	I-General_Concept
architectures	I-General_Concept
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
2018	O
,	O
work	O
undertaken	O
in	O
the	O
United	O
States	O
by	O
cybersecurity	O
researchers	O
at	O
NIST	O
and	O
NCCoE	O
led	O
to	O
the	O
publication	O
of	O
SP	O
800-207	O
,	O
Zero	B-General_Concept
Trust	I-General_Concept
Architecture	I-General_Concept
.	O
</s>
<s>
The	O
publication	O
defines	O
zero	B-General_Concept
trust	I-General_Concept
(	O
ZT	O
)	O
as	O
a	O
collection	O
of	O
concepts	O
and	O
ideas	O
designed	O
to	O
reduce	O
the	O
uncertainty	O
in	O
enforcing	O
accurate	O
,	O
per-request	O
access	O
decisions	O
in	O
information	O
systems	O
and	O
services	O
in	O
the	O
face	O
of	O
a	O
network	O
viewed	O
as	O
compromised	O
.	O
</s>
<s>
A	O
zero	B-General_Concept
trust	I-General_Concept
architecture	I-General_Concept
(	O
ZTA	O
)	O
is	O
an	O
enterprise	O
's	O
cyber	O
security	O
plan	O
that	O
utilizes	O
zero	B-General_Concept
trust	I-General_Concept
concepts	O
and	O
encompasses	O
component	O
relationships	O
,	O
workflow	O
planning	O
,	O
and	O
access	O
policies	O
.	O
</s>
<s>
Therefore	O
,	O
a	O
zero	B-General_Concept
trust	I-General_Concept
enterprise	O
is	O
the	O
network	O
infrastructure	O
(	O
physical	O
and	O
virtual	O
)	O
and	O
operational	O
policies	O
that	O
are	O
in	O
place	O
for	O
an	O
enterprise	O
as	O
a	O
product	O
of	O
a	O
zero	B-General_Concept
trust	I-General_Concept
architecture	I-General_Concept
plan	O
.	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	B-General_Concept
trust	I-General_Concept
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>
<s>
An	O
alternative	O
but	O
consistent	O
approach	O
is	O
taken	O
by	O
NCSC	O
,	O
in	O
identifying	O
the	O
key	O
principles	O
behind	O
zero	B-General_Concept
trust	I-General_Concept
architectures	I-General_Concept
:	O
</s>
