<s>
Pseudonymization	B-General_Concept
is	O
a	O
data	B-General_Concept
management	I-General_Concept
and	O
de-identification	O
procedure	O
by	O
which	O
personally	O
identifiable	O
information	O
fields	O
within	O
a	O
data	O
record	O
are	O
replaced	O
by	O
one	O
or	O
more	O
artificial	O
identifiers	O
,	O
or	O
pseudonyms	O
.	O
</s>
<s>
A	O
single	O
pseudonym	O
for	O
each	O
replaced	O
field	O
or	O
collection	O
of	O
replaced	O
fields	O
makes	O
the	O
data	O
record	O
less	O
identifiable	O
while	O
remaining	O
suitable	O
for	O
data	B-General_Concept
analysis	I-General_Concept
and	O
data	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Pseudonymization	B-General_Concept
(	O
or	O
pseudonymisation	B-General_Concept
,	O
the	O
spelling	O
under	O
European	O
guidelines	O
)	O
is	O
one	O
way	O
to	O
comply	O
with	O
the	O
European	O
Union	O
's	O
new	O
General	O
Data	O
Protection	O
Regulation	O
(	O
GDPR	O
)	O
demands	O
for	O
secure	O
data	O
storage	O
of	O
personal	O
information	O
.	O
</s>
<s>
Pseudonymized	B-General_Concept
data	O
can	O
be	O
restored	O
to	O
its	O
original	O
state	O
with	O
the	O
addition	O
of	O
information	O
which	O
allows	O
individuals	O
to	O
be	O
re-identified	O
.	O
</s>
<s>
The	O
European	O
Data	O
Protection	O
Supervisor	O
(	O
EDPS	O
)	O
on	O
9	O
December	O
2021	O
highlighted	O
pseudonymization	B-General_Concept
as	O
the	O
top	O
technical	O
supplementary	O
measure	O
for	O
Schrems	O
II	O
compliance	O
.	O
</s>
<s>
Less	O
than	O
two	O
weeks	O
later	O
,	O
the	O
EU	O
Commission	O
highlighted	O
pseudonymization	B-General_Concept
as	O
an	O
essential	O
element	O
of	O
the	O
equivalency	O
decision	O
for	O
South	O
Korea	O
,	O
which	O
is	O
the	O
status	O
that	O
was	O
lost	O
by	O
the	O
United	O
States	O
under	O
the	O
Schrems	O
II	O
ruling	O
by	O
the	O
Court	O
of	O
Justice	O
of	O
the	O
European	O
Union	O
(	O
CJEU	O
)	O
.	O
</s>
<s>
The	O
importance	O
of	O
GDPR-compliant	O
pseudonymization	B-General_Concept
increased	O
dramatically	O
in	O
June	O
2021	O
when	O
the	O
European	O
Data	O
Protection	O
Board	O
(	O
EDPB	O
)	O
and	O
the	O
European	O
Commission	O
highlighted	O
GDPR-compliant	O
Pseudonymisation	B-General_Concept
as	O
the	O
state-of-the-art	O
technical	O
supplementary	O
measure	O
for	O
the	O
ongoing	O
lawful	O
use	O
of	O
EU	O
personal	O
data	O
when	O
using	O
third	O
country	O
(	O
i.e.	O
,	O
non-EU	O
)	O
cloud	O
processors	O
or	O
remote	O
service	O
providers	O
under	O
the	O
"	O
Schrems	O
II	O
"	O
ruling	O
by	O
the	O
CJEU	O
.	O
</s>
<s>
Under	O
the	O
GDPR	O
and	O
final	O
EDPB	O
Schrems	O
II	O
Guidance	O
,	O
the	O
term	O
pseudonymization	B-General_Concept
requires	O
a	O
new	O
protected	O
“	O
state	O
”	O
of	O
data	O
,	O
producing	O
a	O
protected	O
outcome	O
that	O
:	O
</s>
<s>
GDPR-compliant	O
pseudonymization	B-General_Concept
requires	O
that	O
data	O
is	O
“	O
anonymous	O
”	O
in	O
the	O
strictest	O
EU	O
sense	O
of	O
the	O
word	O
–	O
globally	O
anonymous	O
–	O
but	O
for	O
-	O
the	O
additional	O
information	O
held	O
separately	O
and	O
made	O
available	O
under	O
controlled	O
conditions	O
as	O
authorized	O
by	O
the	O
data	O
controller	O
for	O
permitted	O
re-identification	O
of	O
individual	O
data	O
subjects	O
.	O
</s>
<s>
Before	O
the	O
Schrems	O
II	O
ruling	O
,	O
pseudonymization	B-General_Concept
was	O
a	O
technique	O
used	O
by	O
security	O
experts	O
or	O
government	O
officials	O
to	O
hide	O
personally	O
identifiable	O
information	O
to	O
maintain	O
data	O
structure	O
and	O
privacy	O
of	O
information	O
.	O
</s>
<s>
After	O
the	O
Schrems	O
II	O
ruling	O
,	O
GDPR-compliant	O
pseudonymization	B-General_Concept
must	O
satisfy	O
the	O
above-noted	O
elements	O
as	O
an	O
"	O
outcome	O
"	O
versus	O
merely	O
a	O
technique	O
.	O
</s>
<s>
The	O
choice	O
of	O
which	O
data	O
fields	O
are	O
to	O
be	O
pseudonymized	B-General_Concept
is	O
partly	O
subjective	O
.	O
</s>
<s>
Data	O
fields	O
that	O
are	O
less	O
identifying	O
,	O
such	O
as	O
date	O
of	O
attendance	O
,	O
are	O
usually	O
not	O
pseudonymized	B-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
given	O
prior	O
knowledge	O
of	O
a	O
few	O
attendance	O
dates	O
it	O
is	O
easy	O
to	O
identify	O
someone	O
's	O
data	O
in	O
a	O
pseudonymized	B-General_Concept
dataset	O
by	O
selecting	O
only	O
those	O
people	O
with	O
that	O
pattern	O
of	O
dates	O
.	O
</s>
<s>
This	O
is	O
an	O
example	O
of	O
an	O
inference	B-Algorithm
attack	I-Algorithm
.	O
</s>
<s>
The	O
weakness	O
of	O
pre-GDPR	O
pseudonymized	B-General_Concept
data	O
to	O
inference	B-Algorithm
attacks	I-Algorithm
is	O
commonly	O
overlooked	O
.	O
</s>
<s>
The	O
AOL	O
example	O
of	O
unauthorized	O
re-identification	O
did	O
not	O
require	O
access	O
to	O
separately	O
kept	O
“	O
additional	O
information	O
”	O
that	O
was	O
under	O
the	O
control	O
of	O
the	O
data	O
controller	O
as	O
is	O
now	O
required	O
for	O
GDPR	O
compliant	O
Pseudonymisation	B-General_Concept
,	O
outlined	O
below	O
under	O
the	O
section	O
"	O
New	O
Definition	O
for	O
Pseudonymization	B-General_Concept
Under	O
GDPR	O
"	O
.	O
</s>
<s>
Protecting	O
statistically	O
useful	O
pseudonymized	B-General_Concept
data	O
from	O
re-identification	O
requires	O
:	O
</s>
<s>
The	O
pseudonym	O
allows	O
tracking	O
back	O
of	O
data	O
to	O
its	O
origins	O
,	O
which	O
distinguishes	O
pseudonymization	B-General_Concept
from	O
anonymization	O
,	O
where	O
all	O
person-related	O
data	O
that	O
could	O
allow	O
backtracking	O
has	O
been	O
purged	O
.	O
</s>
<s>
Pseudonymization	B-General_Concept
is	O
an	O
issue	O
in	O
,	O
for	O
example	O
,	O
patient-related	O
data	O
that	O
has	O
to	O
be	O
passed	O
on	O
securely	O
between	O
clinical	O
centers	O
.	O
</s>
<s>
The	O
application	O
of	O
pseudonymization	B-General_Concept
to	O
e-health	B-Application
intends	O
to	O
preserve	O
the	O
patient	O
's	O
privacy	O
and	O
data	O
confidentiality	O
.	O
</s>
<s>
In	O
the	O
US	O
,	O
HIPAA	O
provides	O
guidelines	O
on	O
how	O
health	O
care	O
data	O
must	O
be	O
handled	O
and	O
data	O
de-identification	O
or	O
pseudonymization	B-General_Concept
is	O
one	O
way	O
to	O
simplify	O
HIPAA	O
compliance	O
.	O
</s>
<s>
However	O
,	O
plain	O
pseudonymization	B-General_Concept
for	O
privacy	O
preservation	O
often	O
reaches	O
its	O
limits	O
when	O
genetic	O
data	O
are	O
involved	O
(	O
see	O
also	O
genetic	O
privacy	O
)	O
.	O
</s>
<s>
Potential	O
solutions	O
are	O
the	O
combination	O
of	O
pseudonymization	B-General_Concept
with	O
fragmentation	O
and	O
encryption	O
.	O
</s>
<s>
An	O
example	O
of	O
application	O
of	O
pseudonymization	B-General_Concept
procedure	O
is	O
creation	O
of	O
datasets	O
for	O
de-identification	O
research	O
by	O
replacing	O
identifying	O
words	O
with	O
words	O
from	O
the	O
same	O
category	O
(	O
e.g.	O
</s>
<s>
Effective	O
as	O
of	O
May	O
25	O
,	O
2018	O
,	O
the	O
EU	O
General	O
Data	O
Protection	O
Regulation	O
(	O
GDPR	O
)	O
defines	O
pseudonymization	B-General_Concept
for	O
the	O
very	O
first	O
time	O
at	O
the	O
EU	O
level	O
in	O
Article	O
4(5 )	O
.	O
</s>
<s>
Under	O
Article	O
4(5 )	O
definitional	O
requirements	O
,	O
data	O
is	O
pseudonymized	B-General_Concept
if	O
it	O
cannot	O
be	O
attributed	O
to	O
a	O
specific	O
data	O
subject	O
without	O
the	O
use	O
of	O
separately	O
kept	O
"	O
additional	O
information.	O
”	O
Pseudonymized	B-General_Concept
data	O
embodies	O
the	O
state	O
of	O
the	O
art	O
in	O
Data	O
Protection	O
by	O
Design	O
and	O
by	O
Default	O
because	O
it	O
requires	O
protection	O
of	O
both	O
direct	O
and	O
indirect	O
identifiers	O
(	O
not	O
just	O
direct	O
)	O
.	O
</s>
<s>
GDPR	O
Data	O
Protection	O
by	O
Design	O
and	O
by	O
Default	O
principles	O
as	O
embodied	O
in	O
pseudonymization	B-General_Concept
require	O
protection	O
of	O
both	O
direct	O
and	O
indirect	O
identifiers	O
so	O
that	O
personal	O
data	O
is	O
not	O
cross-referenceable	O
(	O
or	O
re-identifiable	O
)	O
via	O
the	O
"	O
Mosaic	O
Effect	O
"	O
without	O
access	O
to	O
“	O
additional	O
information	O
”	O
that	O
is	O
kept	O
separately	O
by	O
the	O
controller	O
.	O
</s>
<s>
GDPR	O
Article	O
25(1 )	O
identifies	O
pseudonymization	B-General_Concept
as	O
an	O
“	O
appropriate	O
technical	O
and	O
organizational	O
measure	O
”	O
and	O
Article	O
25(2 )	O
requires	O
controllers	O
to	O
:	O
</s>
<s>
Technologies	O
like	O
pseudonymization	B-General_Concept
that	O
enforce	O
Data	O
Protection	O
by	O
Design	O
and	O
by	O
Default	O
show	O
individual	O
data	O
subjects	O
that	O
in	O
addition	O
to	O
coming	O
up	O
with	O
new	O
ways	O
to	O
derive	O
value	O
from	O
data	O
,	O
organizations	O
are	O
pursuing	O
equally	O
innovative	O
technical	O
approaches	O
to	O
protecting	O
data	O
privacy	O
—	O
an	O
especially	O
sensitive	O
and	O
topical	O
issue	O
given	O
the	O
epidemic	O
of	O
data	O
security	O
breaches	O
around	O
the	O
globe	O
.	O
</s>
<s>
Pseudonymisation	B-General_Concept
,	O
as	O
newly	O
defined	O
under	O
the	O
GDPR	O
,	O
is	O
a	O
means	O
of	O
helping	O
to	O
achieve	O
Data	O
Protection	O
by	O
Design	O
and	O
by	O
Default	O
to	O
earn	O
and	O
maintain	O
trust	O
and	O
more	O
effectively	O
serve	O
businesses	O
,	O
researchers	O
,	O
healthcare	O
providers	O
,	O
and	O
everyone	O
who	O
relies	O
on	O
the	O
integrity	O
of	O
data	O
.	O
</s>
<s>
GDPR	O
compliant	O
pseudonymization	B-General_Concept
not	O
only	O
enables	O
greater	O
privacy-respectful	O
use	O
of	O
data	O
in	O
today	O
's	O
"	O
big	B-Application
data	I-Application
"	O
world	O
of	O
data	O
sharing	O
and	O
combining	O
,	O
but	O
it	O
also	O
enables	O
data	O
controllers	O
and	O
processors	O
to	O
reap	O
explicit	O
benefits	O
under	O
the	O
GDPR	O
for	O
correctly	O
pseudonymized	B-General_Concept
data.The	O
benefits	O
of	O
properly	O
pseudonymized	B-General_Concept
data	O
are	O
highlighted	O
in	O
multiple	O
GDPR	O
Articles	O
,	O
including	O
:	O
</s>
<s>
Article	O
6(4 )	O
as	O
a	O
safeguard	O
to	O
help	O
ensure	O
the	O
compatibility	O
of	O
new	O
data	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Article	O
89(1 )	O
as	O
a	O
safeguard	O
in	O
connection	O
with	O
processing	O
for	O
archiving	O
purposes	O
in	O
the	O
public	O
interest	O
;	O
scientific	O
or	O
historical	O
research	O
purposes	O
;	O
or	O
statistical	O
purposes	O
;	O
moreover	O
,	O
the	O
benefits	O
of	O
pseudonymization	B-General_Concept
under	O
Article	O
89(1 )	O
also	O
provide	O
greater	O
flexibility	O
under	O
:	O
</s>
<s>
In	O
addition	O
,	O
properly	O
pseudonymized	B-General_Concept
data	O
is	O
recognized	O
in	O
Article	O
29	O
Working	O
Party	O
Opinion	O
06/2014	O
as	O
playing	O
“	O
…	O
a	O
role	O
with	O
regard	O
to	O
the	O
evaluation	O
of	O
the	O
potential	O
impact	O
of	O
the	O
processing	O
on	O
the	O
data	O
subject	O
...	O
tipping	O
the	O
balance	O
in	O
favour	O
of	O
the	O
controller	O
”	O
to	O
help	O
support	O
Legitimate	O
Interest	O
processing	O
as	O
a	O
legal	O
basis	O
under	O
Article	O
GDPR	O
6(1 )	O
(	O
f	O
)	O
.	O
</s>
<s>
Benefits	O
from	O
processing	O
personal	O
data	O
using	O
pseudonymized-enabled	O
Legitimate	O
Interest	O
as	O
a	O
legal	O
basis	O
under	O
the	O
GDPR	O
include	O
,	O
without	O
limitation	O
:	O
</s>
