<s>
Data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
in	O
information	B-General_Concept
technology	I-General_Concept
means	O
data	O
that	O
is	O
housed	O
physically	O
on	O
computer	B-General_Concept
data	I-General_Concept
storage	I-General_Concept
in	O
any	O
digital	O
form	O
(	O
e.g.	O
</s>
<s>
cloud	O
storage	O
,	O
file	B-Application
hosting	I-Application
services	I-Application
,	O
databases	O
,	O
data	O
warehouses	O
,	O
spreadsheets	B-Application
,	O
archives	O
,	O
tapes	O
,	O
off-site	O
or	O
cloud	O
backups	O
,	O
mobile	B-Application
devices	I-Application
etc	O
.	O
)	O
.	O
</s>
<s>
Data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
includes	O
both	O
structured	O
and	O
unstructured	O
data	O
.	O
</s>
<s>
The	O
security	O
options	O
used	O
for	O
this	O
type	O
of	O
data	O
are	O
broadly	O
referred	O
to	O
as	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
protection	O
(	O
DARP	O
)	O
.	O
</s>
<s>
Data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
is	O
used	O
as	O
a	O
complement	O
to	O
the	O
terms	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
and	O
data	B-General_Concept
in	I-General_Concept
transit	I-General_Concept
which	O
together	O
define	O
the	O
three	O
states	O
of	O
digital	O
data	O
(	O
see	O
Figure	O
1	O
)	O
.	O
</s>
<s>
There	O
is	O
some	O
disagreement	O
regarding	O
the	O
difference	O
between	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
and	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
.	O
</s>
<s>
Data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
generally	O
refers	O
to	O
data	O
stored	O
in	O
persistent	O
storage	O
(	O
disk	O
,	O
tape	O
)	O
while	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
generally	O
refers	O
to	O
data	O
being	O
processed	O
by	O
a	O
computer	O
central	O
processing	O
unit	O
(	O
CPU	B-Device
)	O
or	O
in	O
random	B-Architecture
access	I-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
,	O
also	O
referred	O
to	O
as	O
main	O
memory	O
or	O
simply	O
memory	O
)	O
.	O
</s>
<s>
"	O
all	O
...	O
data	O
in	O
computer	B-General_Concept
storage	I-General_Concept
while	O
excluding	O
data	O
that	O
is	O
traversing	O
a	O
network	O
or	O
temporarily	O
residing	O
in	O
computer	O
memory	O
to	O
be	O
read	O
or	O
updated.	O
"	O
</s>
<s>
Data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
includes	O
but	O
is	O
not	O
limited	O
to	O
archived	O
data	O
,	O
data	O
which	O
is	O
not	O
accessed	O
or	O
changed	O
frequently	O
,	O
files	O
stored	O
on	O
hard	O
drives	O
,	O
USB	O
thumb	O
drives	O
,	O
files	O
stored	O
on	O
backup	O
tape	O
and	O
disks	O
,	O
and	O
also	O
files	O
stored	O
off-site	O
or	O
on	O
a	O
storage	O
area	O
network	O
(	O
SAN	O
)	O
.	O
"	O
</s>
<s>
Data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
has	O
also	O
been	O
taken	O
to	O
mean	O
“	O
active	O
data	O
”	O
in	O
the	O
context	O
of	O
being	O
in	O
a	O
database	O
or	O
being	O
manipulated	O
by	O
an	O
application	O
.	O
</s>
<s>
For	O
example	O
,	O
some	O
enterprise	O
encryption	O
gateway	O
solutions	O
for	O
the	O
cloud	O
claim	O
to	O
encrypt	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
,	O
data	B-General_Concept
in	I-General_Concept
transit	I-General_Concept
and	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
.	O
</s>
<s>
which	O
never	O
changes	O
)	O
,	O
regardless	O
of	O
its	O
storage	O
medium	O
,	O
is	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
and	O
active	O
data	O
subject	O
to	O
constant	O
or	O
frequent	O
change	O
is	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
.	O
</s>
<s>
The	O
imprecise	O
nature	O
of	O
terms	O
such	O
as	O
“	O
constant	O
”	O
and	O
“	O
frequent	O
”	O
means	O
that	O
some	O
stored	O
data	O
cannot	O
be	O
comprehensively	O
defined	O
as	O
either	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
or	O
in	O
use	O
.	O
</s>
<s>
These	O
definitions	O
could	O
be	O
taken	O
to	O
assume	O
that	O
Data	B-General_Concept
at	I-General_Concept
Rest	I-General_Concept
is	O
a	O
superset	O
of	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
;	O
however	O
,	O
data	B-General_Concept
in	I-General_Concept
use	I-General_Concept
,	O
subject	O
to	O
frequent	O
change	O
,	O
has	O
distinct	O
processing	O
requirements	O
from	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
,	O
whether	O
completely	O
static	O
or	O
subject	O
to	O
occasional	O
change	O
.	O
</s>
<s>
The	O
division	O
of	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
into	O
the	O
sub-categories	O
"	O
static	O
"	O
and	O
"	O
inconstant	O
"	O
addresses	O
this	O
distinction	O
(	O
see	O
Figure	O
2	O
)	O
..	O
</s>
<s>
Because	O
of	O
its	O
nature	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
is	O
of	O
increasing	O
concern	O
to	O
businesses	O
,	O
government	O
agencies	O
and	O
other	O
institutions	O
.	O
</s>
<s>
Mobile	B-Application
devices	I-Application
are	O
often	O
subject	O
to	O
specific	O
security	O
protocols	O
to	O
protect	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
from	O
unauthorized	O
access	O
when	O
lost	O
or	O
stolen	O
and	O
there	O
is	O
an	O
increasing	O
recognition	O
that	O
database	O
management	O
systems	O
and	O
file	O
servers	O
should	O
also	O
be	O
considered	O
as	O
at	O
risk	O
;	O
the	O
longer	O
data	O
is	O
left	O
unused	O
in	O
storage	O
,	O
the	O
more	O
likely	O
it	O
might	O
be	O
retrieved	O
by	O
unauthorized	O
individuals	O
outside	O
the	O
network	O
.	O
</s>
<s>
Data	O
encryption	O
,	O
which	O
prevents	O
data	O
visibility	O
in	O
the	O
event	O
of	O
its	O
unauthorized	O
access	O
or	O
theft	O
,	O
is	O
commonly	O
used	O
to	O
protect	O
data	B-General_Concept
in	I-General_Concept
motion	I-General_Concept
and	O
increasingly	O
promoted	O
for	O
protecting	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
.	O
</s>
<s>
The	O
encryption	O
of	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
should	O
only	O
include	O
strong	O
encryption	O
methods	O
such	O
as	O
AES	B-Algorithm
or	O
RSA	B-Architecture
.	O
</s>
<s>
Tokenization	O
is	O
a	O
non-mathematical	O
approach	O
to	O
protecting	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
that	O
replaces	O
sensitive	O
data	O
with	O
non-sensitive	O
substitutes	O
,	O
referred	O
to	O
as	O
tokens	O
,	O
which	O
have	O
no	O
extrinsic	O
or	O
exploitable	O
meaning	O
or	O
value	O
.	O
</s>
<s>
Lower	O
processing	O
and	O
storage	O
requirements	O
makes	O
tokenization	O
an	O
ideal	O
method	O
of	O
securing	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
in	O
systems	O
that	O
manage	O
large	O
volumes	O
of	O
data	O
.	O
</s>
<s>
A	O
further	O
method	O
of	O
preventing	O
unwanted	O
access	O
to	O
data	B-General_Concept
at	I-General_Concept
rest	I-General_Concept
is	O
the	O
use	O
of	O
data	O
federation	O
especially	O
when	O
data	O
is	O
distributed	O
globally	O
(	O
e.g.	O
</s>
