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h
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tes
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re
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tralize
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t
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ty
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e
sig
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tatio
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h
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se
d
f
ra
m
e
wo
rk
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K
ey
w
o
r
d
s
:
C
er
tific
ate
au
th
o
r
ity
C
er
tific
ate
v
er
if
ica
tio
n
Dec
en
tr
alize
d
ap
p
licatio
n
Dig
ital c
er
tific
ate
Sm
ar
t c
o
n
tr
ac
ts
T
h
is i
s
a
n
o
p
e
n
a
c
c
e
ss
a
rticle
u
n
d
e
r th
e
CC B
Y
-
SA
li
c
e
n
se
.
C
o
r
r
e
s
p
o
nd
ing
A
uth
o
r
:
Ma
zlih
am
Mo
h
d
Su
’
u
d
Facu
lty
o
f
C
o
m
p
u
tin
g
an
d
I
n
f
o
r
m
atics,
Mu
ltime
d
ia
Un
iv
er
s
ity
C
y
b
er
jay
a,
Selan
g
o
r
,
Ma
lay
s
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E
m
ail: m
az
lih
am
@
m
m
u
.
ed
u
.
m
y
1.
I
NT
RO
D
UCT
I
O
N
Un
d
er
th
e
cu
r
r
en
t
s
itu
atio
n
,
m
is
lead
in
g
ce
r
tific
atio
n
s
ar
e
a
h
u
g
e
p
r
o
b
lem
.
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o
m
p
an
ies
th
at
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ec
r
u
it
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s
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d
s
o
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ir
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t
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tu
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ig
n
if
ican
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m
o
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y
to
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av
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th
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ed
u
ca
tio
n
al
cr
e
d
en
t
ials
an
d
tr
an
s
cr
ip
ts
co
n
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ir
m
e
d
.
W
e
p
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ed
t
h
e
i
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f
a
Dig
ital
C
e
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tific
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I
n
f
r
astru
ctu
r
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o
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th
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a
u
th
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ti
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tio
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o
f
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a
d
em
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d
eg
r
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tili
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g
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lo
ck
c
h
ain
tech
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o
lo
g
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t
o
s
o
lv
e
th
is
c
h
allen
g
e.
T
h
e
r
o
le
o
f
u
n
iv
e
r
s
ities
in
is
s
u
in
g
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ain
tain
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g
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ce
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tify
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g
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i
p
lo
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as
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co
s
tly
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d
tim
e
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co
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s
u
m
in
g
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Fak
e
ac
ad
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ic
cr
e
d
e
n
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ar
e
b
ec
o
m
in
g
in
cr
ea
s
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ly
co
m
m
o
n
in
th
e
c
o
u
n
tr
y
.
I
d
en
tif
y
in
g
it
th
r
o
u
g
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o
u
t
jo
b
v
ettin
g
,
esp
ec
ially
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g
o
v
er
n
m
en
t
p
o
s
ts
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co
r
r
u
p
ti
o
n
h
as
h
el
p
ed
th
e
r
is
e
o
f
th
is
w
r
o
n
g
d
o
in
g
.
C
o
m
p
an
i
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to
g
eth
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with
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o
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m
en
t
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f
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ajo
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tific
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u
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d
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p
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d
ay
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C
o
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s
p
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b
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eq
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tem
in
ef
f
icien
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[
1
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.
T
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ac
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s
titu
tio
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d
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(
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a
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alif
icatio
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id
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s
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ata
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r
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[
2
]
.
T
h
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in
teg
r
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n
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f
b
lo
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c
h
ain
tec
h
n
o
lo
g
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with
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s
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m
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ch
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b
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to
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s
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.
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ies
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[
3
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.
C
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u
n
ctio
n
s
as
wid
ely
ad
o
p
t
e
d
s
o
lu
tio
n
s
f
o
r
d
ata
in
teg
r
ity
s
in
ce
t
h
ey
en
a
b
le
th
e
v
alid
atio
n
o
f
f
iles
an
d
ce
r
tific
ates
with
o
u
t
m
o
d
if
icatio
n
s
to
o
r
i
g
in
al
co
n
ten
t.
B
lo
ck
s
o
f
tech
n
o
lo
g
y
c
r
ea
te
u
n
alter
a
b
le
y
et
tr
an
s
p
ar
en
t
f
r
am
ewo
r
k
s
to
m
an
ag
e
ce
r
tific
ate
f
ac
ilit
atio
n
a
n
d
v
alid
atio
n
task
s
.
I
n
ter
f
ac
e
v
er
if
icatio
n
b
ec
o
m
es
s
ec
u
r
e
th
r
o
u
g
h
cr
y
p
to
g
r
ap
h
ic
h
ash
f
u
n
ctio
n
s
b
ec
au
s
e
th
ese
to
o
ls
p
r
o
d
u
ce
s
p
ec
if
ic
d
ig
ital
ce
r
tific
ate
f
in
g
er
p
r
in
ts
[
4
]
.
Z
er
o
-
k
n
o
wled
g
e
p
r
o
o
f
tech
n
iq
u
es
in
v
esti
g
ate
m
eth
o
d
s
to
au
th
e
n
ticate
ce
r
tific
ates
wh
ile
m
ain
ta
in
in
g
s
ec
r
e
cy
ab
o
u
t
s
en
s
itiv
e
in
f
o
r
m
atio
n
s
o
as
to
im
p
r
o
v
e
p
r
iv
ac
y
a
n
d
s
ec
u
r
ity
[
5
]
.
T
h
e
d
ev
el
o
p
m
en
t
o
f
d
e
ce
n
tr
alize
d
s
y
s
tem
s
h
as
ad
d
r
ess
ed
m
u
ltip
le
ch
allen
g
es
in
ce
r
tific
ates
m
an
ag
e
m
en
t
b
u
t
s
ca
lab
ilit
y
p
r
o
b
lem
s
wh
en
p
r
o
ce
s
s
in
g
n
u
m
er
o
u
s
ce
r
tific
ates
an
d
h
i
g
h
co
s
ts
an
d
o
p
er
atio
n
al
co
m
p
lex
ity
as
well
as
co
n
f
u
s
in
g
u
s
er
in
ter
f
ac
es
an
d
p
r
iv
ac
y
r
is
k
s
wh
en
v
er
if
y
in
g
ce
r
tific
ates
p
er
s
is
t
as
o
n
g
o
in
g
is
s
u
es
[
6
]
.
T
h
e
p
r
o
p
o
s
ed
r
esear
ch
d
ev
elo
p
s
a
n
in
n
o
v
ativ
e
b
l
o
ck
ch
ain
s
y
s
tem
f
o
r
d
ig
ital
ce
r
tific
atio
n
wh
ic
h
f
ix
es
ex
is
tin
g
s
y
s
tem
d
ef
icien
cies.
A
d
if
f
er
en
t
ap
p
r
o
ac
h
co
m
b
in
es
r
ea
l
-
tim
e
v
er
if
icatio
n
ca
p
ab
ilit
ies
with
ze
r
o
-
k
n
o
wled
g
e
p
r
o
o
f
m
ec
h
an
is
m
s
an
d
a
web
-
b
ased
ap
p
licatio
n
(
C
E
R
T
I
FICATE
L
Y)
to
p
r
o
v
id
e
s
ec
u
r
e
an
d
c
o
n
v
e
n
ien
t
s
er
v
ice.
T
h
e
s
y
s
tem
ac
h
iev
es
n
u
m
er
o
u
s
u
p
g
r
ad
es
th
r
o
u
g
h
i
n
s
tan
t
ce
r
tific
ate
au
th
en
ticati
o
n
alo
n
g
with
f
r
ee
d
ata
r
etr
i
ev
al
an
d
i
n
cr
ea
s
es
p
r
iv
ac
y
th
r
o
u
g
h
ze
r
o
-
k
n
o
wled
g
e
p
r
o
o
f
an
d
th
e
ca
p
ab
ilit
y
to
p
r
o
ce
s
s
lar
g
e
tr
an
s
ac
tio
n
l
o
ad
s
.
Po
s
s
ib
le
s
o
lu
tio
n
s
in
clu
d
e
a
d
atab
ase
with
o
u
t
th
e
a
b
ilit
y
to
u
p
d
ate
it,
a
d
ig
ital
s
ig
n
atu
r
e
,
o
r
a
b
lo
ck
ch
ain
.
A
h
ash
f
u
n
ctio
n
i
s
a
f
u
n
ctio
n
th
at
ac
ce
p
ts
a
d
at
a
in
p
u
t
a
n
d
p
r
o
d
u
ce
s
a
p
r
ed
ic
tab
le
r
esu
lt
o
u
tp
u
t
v
alu
e
b
ased
o
n
th
at
in
p
u
t
v
alu
e.
W
h
en
ex
ec
u
tin
g
th
e
h
ash
,
t
h
e
o
u
tp
u
t
will
alwa
y
s
r
ec
eiv
e
th
e
s
am
e
f
in
al
wo
r
k
f
o
r
wh
atev
er
x
in
p
u
t v
alu
e.
As
a
r
esu
lt,
a
h
ash
f
u
n
ctio
n
tak
es in
p
u
t (
th
at
ca
n
b
e
an
y
d
ata
,
s
u
ch
as in
teg
er
s
,
an
d
f
iles
)
an
d
p
r
o
d
u
ce
s
a
h
ash
.
A
h
ex
ad
ec
im
al
n
u
m
b
er
is
c
o
m
m
o
n
ly
u
s
ed
to
r
ep
r
esen
t
a
h
ash
.
C
r
y
p
to
g
r
ap
h
y
Hash
f
u
n
ctio
n
s
.
T
h
er
e
ar
e
m
an
y
u
s
es
f
o
r
h
ash
f
u
n
ctio
n
s
,
b
u
t
f
ile
i
n
teg
r
it
y
c
h
ec
k
is
o
n
e
o
f
t
h
e
m
o
s
t
co
m
m
o
n
.
Hash
f
u
n
ctio
n
s
o
n
d
ata
f
iles
ar
e
g
en
er
ated
with
it.
T
h
is
ap
p
licatio
n
g
iv
es th
e
u
s
er
co
n
f
id
en
ce
in
th
e
d
ata’
s
ac
cu
r
ac
y
.
I
n
th
is
p
ap
er
we
h
a
v
e
d
e
v
elo
p
ed
a
s
o
lu
tio
n
th
at
ca
n
g
en
e
r
ate
a
b
l
o
ck
ch
ain
b
ased
d
ig
ital
c
er
tific
ate
an
d
it
ca
n
b
e
v
er
if
iab
le
a
n
y
o
r
g
an
izatio
n
o
r
in
s
titu
te
o
r
a
s
tu
d
e
n
t its
elf
.
−
T
h
e
in
s
titu
te
ca
n
g
en
e
r
ate
a
d
i
g
ital c
er
tific
ate
u
s
in
g
b
lo
c
k
ch
ain
tech
n
o
lo
g
y
.
−
T
h
e
s
tu
d
en
t
o
r
an
y
v
er
i
f
ier
ca
n
v
er
i
f
y
t
h
e
h
ash
o
f
th
e
d
ig
ital
ce
r
tific
ate
at
an
y
tim
e
with
th
e
we
b
ap
p
licatio
n
n
am
e
as C
E
R
T
I
FI
C
AT
E
L
Y
an
d
d
o
wn
lo
a
d
th
e
d
ig
ital c
er
tific
ate.
−
Z
er
o
-
k
n
o
wled
g
e
p
r
o
o
f
h
as
b
ee
n
em
p
lo
y
ed
in
th
e
d
esig
n
o
f
t
h
e
s
u
g
g
ested
s
ch
em
e
t
o
en
s
u
r
e
th
e
ap
p
licatio
n
’
s
.
T
h
e
r
esear
ch
p
r
o
p
o
s
es
a
b
lo
ck
ch
ain
-
b
ased
d
ig
ital
ce
r
tific
ate
s
tr
u
ctu
r
e
wh
ich
in
teg
r
ate
s
r
ea
l
-
tim
e
au
th
en
ticatio
n
with
ze
r
o
-
k
n
o
wled
g
e
p
r
o
o
f
al
o
n
g
with
th
e
C
E
R
T
I
FIC
AT
E
L
Y
web
ap
p
li
ca
tio
n
f
o
r
p
r
o
v
id
in
g
r
o
b
u
s
t
s
ec
u
r
ity
an
d
ac
ce
s
s
ib
ilit
y
.
T
h
e
p
latf
o
r
m
allo
ws
ce
r
tific
ate
v
er
if
icatio
n
to
p
r
o
ce
ed
with
o
u
t
h
u
m
a
n
ass
is
tan
ce
o
r
in
te
r
m
ed
iates
p
r
o
v
id
in
g
in
s
tan
tan
eo
u
s
ac
cu
r
at
e
r
esu
lts
.
Z
er
o
-
k
n
o
wled
g
e
p
r
o
o
f
i
n
th
is
s
y
s
tem
en
s
u
r
es
p
r
iv
ate
d
ata
p
r
o
tectio
n
wh
ile
en
a
b
lin
g
ce
r
tific
ate
au
t
h
en
ticatio
n
.
T
h
e
b
lo
ck
c
h
ain
s
y
s
tem
en
ab
les
u
s
er
s
to
r
etr
iev
e
s
to
r
e
d
ce
r
tific
ates
with
o
u
t
ch
ar
g
in
g
f
ee
s
as
C
E
R
T
I
FICATE
L
Y
o
p
er
ates
with
o
u
t
g
as
co
s
ts
m
ak
in
g
th
e
wh
o
le
p
r
o
ce
s
s
m
o
r
e
af
f
o
r
d
ab
le
an
d
s
im
p
le
to
u
s
e.
User
s
ca
n
n
av
ig
ate
th
e
p
latf
o
r
m
th
r
o
u
g
h
a
u
s
er
-
f
r
ien
d
ly
d
esig
n
wh
ich
lets
in
s
titu
tio
n
s
an
d
v
er
if
ier
s
ca
r
r
y
o
u
t
ce
r
tific
ate
d
o
cu
m
en
tatio
n
an
d
v
er
i
f
icatio
n
o
p
er
atio
n
s
ef
f
i
cien
tly
.
T
h
e
s
y
s
tem
m
ain
tain
s
its
p
er
f
o
r
m
an
ce
at
p
ea
k
lev
els
ev
en
wh
en
h
an
d
lin
g
ex
ten
s
iv
e
tr
an
s
ac
tio
n
ac
tiv
ities
b
ec
au
s
e
its
d
esig
n
s
u
p
p
o
r
ts
h
ig
h
s
ca
lab
ilit
y
.
Prim
ar
y
co
n
tr
i
b
u
tio
n
s
o
f
th
is
r
esear
ch
p
ap
er
c
o
n
s
is
t o
f
th
ese
k
ey
p
o
i
n
ts
.
−
B
lo
ck
ch
ain
tech
n
o
lo
g
y
u
s
es
cr
y
p
to
g
r
ap
h
ic
h
ash
in
g
to
s
ec
u
r
e
d
ata
s
o
tam
p
er
in
g
b
ec
o
m
es
im
p
o
s
s
ib
le
af
ter
d
ata
s
to
r
ag
e
o
cc
u
r
s
.
−
T
h
e
ze
r
o
-
k
n
o
wled
g
e
p
r
o
o
f
s
y
s
tem
s
en
ab
le
th
e
s
y
s
tem
to
v
er
if
y
cr
ed
e
n
tials
with
o
u
t
leak
in
g
an
y
s
en
s
itiv
e
in
f
o
r
m
atio
n
to
m
ain
tain
b
o
th
p
r
iv
ac
y
an
d
s
ec
u
r
ity
.
−
T
h
e
C
E
R
T
I
FICATE
L
Y
p
latf
o
r
m
en
a
b
les
au
to
m
atic
r
ea
l
-
tim
e
v
er
if
icatio
n
n
ee
d
s
n
o
h
u
m
an
in
v
o
l
v
em
en
t
f
o
r
m
a
n
u
al
p
r
o
ce
s
s
es th
u
s
ac
h
iev
in
g
q
u
ick
r
esu
lts
with
ac
cu
r
ate
v
er
if
icatio
n
s
.
−
User
s
b
en
ef
it
f
r
o
m
n
o
g
as
f
ee
s
alo
n
g
with
r
ed
u
ce
d
o
p
er
atio
n
al
ex
p
en
s
es
t
h
r
o
u
g
h
f
r
ee
ce
r
tif
icate
r
etr
iev
al
o
n
th
e
s
y
s
tem
p
latf
o
r
m
.
−
T
h
e
p
latf
o
r
m
m
ai
n
tain
s
its
h
ig
h
-
lev
el
o
p
er
atio
n
al
p
er
f
o
r
m
a
n
ce
ev
en
wh
en
h
an
d
lin
g
h
ea
v
y
tr
an
s
ac
tio
n
v
o
lu
m
es b
ec
au
s
e
its
d
esig
n
s
p
ec
if
ically
ca
ter
s
to
in
cr
ea
s
ed
wo
r
k
lo
ad
d
em
an
d
s
.
−
A
u
s
er
-
f
r
ien
d
ly
ar
r
an
g
em
en
t
ex
is
ts
f
o
r
in
s
titu
tio
n
s
an
d
v
er
if
ier
s
th
r
o
u
g
h
C
E
R
T
I
FICATE
L
Y
th
at
p
r
o
m
o
tes s
m
o
o
t
h
o
p
e
r
atio
n
s
a
n
d
b
etter
u
s
e
ex
p
er
ien
ce
s
.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
SS
N
:
2
5
0
2
-
4
7
5
2
I
n
d
o
n
esian
J
E
lec
E
n
g
&
C
o
m
p
Sci
,
Vo
l.
40
,
No
.
1
,
Octo
b
er
20
25
:
236
-
2
6
2
238
−
B
lo
ck
ch
ain
co
n
s
tr
u
cts
an
u
n
c
h
an
g
ea
b
le
tr
an
s
p
a
r
an
t
s
y
s
tem
to
m
an
ag
e
ce
r
tific
ates
wh
ich
im
p
r
o
v
es
b
o
t
h
tr
u
s
t le
v
els an
d
ac
co
u
n
tab
ili
ty
ca
p
ab
ilit
ies.
−
T
h
e
co
m
b
in
atio
n
o
f
h
ash
co
m
p
ar
is
o
n
f
o
r
v
er
if
icatio
n
elim
in
ates
f
ak
e
ac
ad
em
ic
cr
ed
en
tial
s
an
d
p
r
o
tects
ed
u
ca
tio
n
al
cr
e
d
en
tials
ag
ain
s
t m
is
r
ep
r
esen
tatio
n
an
d
d
ec
ep
ti
o
n
.
−
T
h
e
s
y
s
tem
en
a
b
les
wo
r
ld
wid
e
ac
ce
s
s
ib
ilit
y
th
r
o
u
g
h
cr
o
s
s
-
b
o
r
d
er
v
e
r
if
ica
tio
n
s
in
ce
it
s
u
p
p
o
r
ts
ex
p
an
s
io
n
o
f
its
ac
cr
ed
ited
in
s
titu
tio
n
s
d
atab
ase
to
im
p
r
o
v
e
i
n
ter
n
atio
n
al
ce
r
tific
ate
r
e
co
g
n
i
tio
n
.
−
T
h
ir
d
-
p
a
r
ty
v
er
if
icatio
n
o
cc
u
r
s
d
ir
ec
tly
b
etwe
en
r
ec
r
u
iter
s
an
d
o
r
g
an
izatio
n
s
th
r
o
u
g
h
th
is
s
y
s
tem
with
o
u
t r
eq
u
i
r
in
g
r
e
p
r
esen
tativ
es f
r
o
m
is
s
u
in
g
in
s
titu
tio
n
s
.
−
Oth
er
p
r
o
f
ess
io
n
al
cr
e
d
en
tials
an
d
licen
s
es
co
u
l
d
b
e
in
teg
r
a
ted
o
n
t
o
th
e
s
y
s
tem
th
r
o
u
g
h
it
s
ex
ten
s
io
n
t
o
b
o
o
s
t sy
s
tem
v
alu
e.
T
h
e
r
esear
ch
o
r
g
a
n
ized
i
n
th
is
o
r
d
e
r
:
Sectio
n
1
p
r
esen
ts
f
u
n
d
am
en
tal
in
f
o
r
m
atio
n
ab
o
u
t
th
e
r
esear
ch
s
u
b
je
ct
to
g
eth
e
r
with
th
e
c
r
itical
p
r
o
b
lem
ar
ea
s
th
at
n
ee
d
f
o
cu
s
in
th
is
p
a
p
er
.
Sectio
n
2
estab
lis
h
es
th
e
f
o
u
n
d
atio
n
o
f
b
lo
ck
c
h
ain
-
b
as
ed
d
ig
ital
ce
r
tific
ates
with
two
p
ar
ts
d
escr
ib
in
g
b
o
th
co
n
ce
p
ts
.
T
h
e
r
esear
ch
s
tu
d
y
Kn
o
wn
as
R
elate
d
W
o
r
k
is
ex
p
lo
r
e
d
in
s
ec
tio
n
3
to
d
em
o
n
s
tr
ate
b
lo
c
k
ch
ain
-
b
ased
d
ig
ital
ce
r
tific
ate
ap
p
licatio
n
s
with
v
er
if
icatio
n
s
tan
d
ar
d
s
.
Sectio
n
4
th
e
e
x
p
er
im
en
tal
Setu
p
s
ec
tio
n
co
n
tain
s
b
o
th
th
e
p
r
o
p
o
s
ed
d
esig
n
an
d
f
r
am
ewo
r
k
to
g
eth
er
with
th
e
p
r
o
g
r
am
m
in
g
lan
g
u
ag
es.
T
h
e
r
esear
ch
d
is
cu
s
s
es
b
lo
ck
ch
ain
-
b
ased
d
ig
ital
ce
r
tific
ates
with
th
eir
v
er
if
icatio
n
f
ea
tu
r
es
alo
n
g
with
all
co
m
p
o
n
en
ts
r
eq
u
ir
ed
t
o
co
n
s
tr
u
ct
s
u
ch
a
s
y
s
tem
.
Sectio
n
5
d
etails
th
e
s
y
s
tem
im
p
lem
en
tatio
n
th
r
o
u
g
h
s
m
ar
t
co
n
tr
ac
ts
cr
ea
tio
n
f
o
r
all
m
o
d
u
les
alo
n
g
with
p
r
esen
ted
c
o
d
e
s
n
ip
p
ets
.
Sectio
n
6
d
escr
ib
es
t
h
e
s
tu
d
y
o
f
th
e
R
esu
lt
an
d
d
is
cu
s
s
io
n
.
Sectio
n
7
p
e
r
f
o
r
m
s
an
an
aly
s
is
o
f
Ver
if
icatio
n
s
c
en
ar
io
v
er
if
icatio
n
o
p
er
atio
n
s
o
n
B
lo
ck
ch
ain
th
r
o
u
g
h
p
e
r
f
o
r
m
an
ce
ev
alu
atio
n
wh
ile
d
is
cu
s
s
in
g
its
o
u
tco
m
e
in
d
ep
th
.
Sectio
n
8
d
escr
ib
es th
e
b
r
ief
co
n
clu
s
io
n
an
d
f
u
tu
r
e
i
m
p
licatio
n
s
.
A.
T
h
e
b
lo
ck
c
h
ain
B
lo
ck
ch
ain
tech
n
o
lo
g
y
f
ac
ilit
ates
co
llab
o
r
ativ
e
i
n
f
o
r
m
atio
n
s
h
ar
in
g
am
o
n
g
m
u
ltip
le
in
d
iv
id
u
als,
en
ab
lin
g
th
em
t
o
co
llectiv
el
y
m
an
a
g
e
a
d
atab
ase
o
f
p
r
o
d
u
cts
th
r
o
u
g
h
a
co
n
-
s
en
s
u
s
m
ec
h
an
is
m
.
T
h
is
ag
r
ee
m
en
t
h
in
g
es
o
n
th
e
p
r
i
n
cip
le
o
f
ac
k
n
o
wled
g
i
n
g
ea
ch
p
a
r
ticip
an
t’
s
co
n
tr
ib
u
tio
n
s
to
ex
ten
d
in
g
th
e
d
atab
ase,
en
s
u
r
in
g
its
in
teg
r
ity
ag
ain
s
t
tam
p
er
in
g
,
u
n
au
t
h
o
r
ized
m
o
d
if
icatio
n
s
,
o
r
d
i
s
r
u
p
tio
n
.
No
tab
l
y
,
cr
y
p
to
cu
r
r
en
cies
lik
e
B
itco
in
r
e
p
r
esen
t
p
r
o
m
in
e
n
t
a
p
p
l
icatio
n
s
o
f
B
lo
ck
ch
ain
[
7
]
.
I
n
th
e
r
ea
lm
o
f
p
er
m
is
s
io
n
less
b
lo
ck
-
ch
ain
s
[8
]
.
T
h
e
ch
o
s
en
co
n
s
en
s
u
s
m
eth
o
d
d
ictates
th
e
s
y
s
tem
’
s
ef
f
ec
tiv
en
ess
an
d
ad
ap
tab
ilit
y
.
C
o
n
s
en
s
u
s
s
y
s
tem
s
m
u
s
t
n
av
ig
ate
ch
alle
n
g
es
s
u
ch
as
b
lo
ck
c
h
ain
f
o
r
k
s
,
No
d
e
d
o
m
in
atio
n
,
p
er
f
o
r
m
an
ce
lim
itatio
n
s
,
a
n
d
p
o
te
n
tial
co
n
s
en
s
u
s
f
ail
u
r
es.
T
wo
p
r
ev
alen
t
m
eth
o
d
s
f
o
r
ac
h
iev
in
g
p
er
m
is
s
io
n
less
co
n
s
en
s
u
s
ar
e
Pro
o
f
o
f
W
o
r
k
(
Po
W
)
an
d
Pro
o
f
o
f
Stak
e
(
Po
S)
Po
W
:
Po
W
o
p
er
ates
b
y
p
r
o
m
p
tin
g
n
o
d
es
to
en
g
ag
e
i
n
co
m
p
etitiv
e
ef
f
o
r
ts
to
s
o
lv
e
cr
y
p
to
g
r
a
p
h
ic
p
u
zz
les,
th
er
eb
y
co
n
s
tr
ain
in
g
a
n
o
d
e’
s
ca
p
ac
ity
t
o
tam
p
er
wi
th
th
e
b
lo
ck
c
h
ain
led
g
e
r
.
Su
c
ce
s
s
f
u
lly
r
eso
lv
in
g
th
e
p
u
zz
l
e
ea
r
n
s
th
e
n
o
d
e
a
r
ewa
r
d
in
th
e
f
o
r
m
o
f
lo
ca
l
cr
y
p
to
cu
r
r
en
cy
,
s
er
v
in
g
as
a
m
o
tiv
atio
n
al
f
ac
to
r
[
9
]
.
No
tab
l
y
,
Po
W
s
er
v
es
as
th
e
co
n
s
en
s
u
s
alg
o
r
ith
m
f
o
r
v
ar
io
u
s
b
lo
ck
c
h
ain
s
y
s
tem
s
,
in
clu
d
in
g
E
th
e
r
eu
m
an
d
B
itco
in
[
1
0
]
.
I
n
th
e
co
n
te
x
t
o
f
an
in
teg
er
,
th
e
Po
W
f
u
n
ctio
n
en
tails
tak
in
g
a
d
ataset
an
d
g
e
n
er
atin
g
b
o
th
a
h
ash
v
alu
e
Po
W
an
d
n
o
n
ce
v
alu
es
co
n
s
is
tin
g
o
f
r
an
d
o
m
b
its
,
illu
s
tr
at
in
g
a
f
u
n
d
am
en
tal
asp
ec
t
o
f
th
e
Po
W
co
n
s
en
s
u
s
alg
o
r
ith
m
.
Po
S:
A
Po
S
s
o
lu
tio
n
ad
d
r
ess
es th
e
is
s
u
e
o
f
Po
W
’
s
h
ig
h
en
er
g
y
co
s
t.
T
ab
le
1
p
r
esen
ts
a
d
etailed
co
m
p
ar
is
o
n
b
etwe
en
Po
W
an
d
Po
S,
two
o
f
t
h
e
m
o
s
t
wid
ely
u
s
ed
co
n
s
en
s
u
s
m
ec
h
an
i
s
m
s
in
b
lo
c
k
ch
ain
tech
n
o
l
o
g
y
.
Po
W
,
u
tili
ze
d
b
y
b
lo
ck
ch
ain
s
lik
e
B
itco
in
,
r
elies
o
n
m
in
er
s
s
o
lv
in
g
co
m
p
lex
m
ath
em
atica
l
p
r
o
b
lem
s
to
v
alid
ate
tr
an
s
ac
tio
n
s
an
d
a
d
d
n
ew
b
lo
ck
s
to
t
h
e
ch
ain
.
I
t
d
elin
ea
tes
k
ey
ch
a
r
ac
ter
is
tics
,
ad
v
an
tag
es,
a
n
d
lim
itatio
n
s
o
f
ea
ch
ap
p
r
o
ac
h
,
aid
in
g
in
th
e
as
s
ess
m
en
t
o
f
th
eir
s
u
itab
ilit
y
f
o
r
v
ar
io
u
s
b
lo
ck
ch
ai
n
ap
p
licatio
n
s
[
1
1
]
.
T
h
is
p
r
o
ce
s
s
en
s
u
r
es
s
ec
u
r
ity
b
u
t
r
eq
u
ir
e
s
s
ig
n
if
ican
t
co
m
p
u
tatio
n
al
p
o
wer
an
d
e
n
er
g
y
,
lead
in
g
to
co
n
ce
r
n
s
ab
o
u
t
s
u
s
tain
ab
ilit
y
.
On
th
e
o
th
er
h
an
d
,
Po
S,
im
p
lem
en
ted
b
y
b
l
o
ck
ch
ain
s
lik
e
E
th
er
eu
m
2
.
0
[
1
2
]
,
elim
in
ates
th
e
n
ee
d
f
o
r
in
ten
s
iv
e
c
o
m
p
u
tatio
n
b
y
s
elec
tin
g
v
alid
ato
r
s
b
ased
o
n
th
e
am
o
u
n
t
o
f
cr
y
p
to
c
u
r
r
en
cy
th
ey
h
o
l
d
an
d
ar
e
willin
g
t
o
"stak
e"
as
c
o
llater
al.
T
h
is
a
p
p
r
o
ac
h
s
ig
n
if
ican
tly
r
ed
u
ce
s
e
n
er
g
y
c
o
n
s
u
m
p
tio
n
wh
ile
m
ain
tain
in
g
d
ec
en
tr
aliza
tio
n
an
d
s
ec
u
r
ity
[
1
3
]
.
T
h
e
ta
b
le
also
co
m
p
ar
es
f
ac
to
r
s
s
u
ch
as
s
ca
lab
ilit
y
,
tr
an
s
ac
tio
n
s
p
ee
d
,
h
ar
d
war
e
r
eq
u
ir
em
en
ts
,
a
n
d
s
u
s
ce
p
tib
ilit
y
to
attac
k
s
,
em
p
h
asizin
g
th
e
tr
ad
e
-
o
f
f
s
b
etwe
en
th
e
r
o
b
u
s
tn
ess
o
f
Po
W
an
d
th
e
ef
f
icien
cy
o
f
Po
S
i
n
d
if
f
er
e
n
t
b
lo
ck
c
h
ain
a
p
p
licatio
n
s
.
T
h
i
s
co
n
s
en
s
u
s
m
eth
o
d
ch
o
o
s
es
r
an
d
o
m
s
y
s
tem
s
tak
e
h
o
ld
er
s
to
ap
p
en
d
b
l
o
ck
s
to
th
e
b
lo
ck
ch
ain
.
T
h
e
f
o
ll
o
w
-
Sato
s
h
i
alg
o
r
ith
m
is
o
n
e
s
u
ch
im
p
lem
en
tatio
n
,
i
n
wh
ic
h
a
r
an
d
o
m
n
ativ
e
c
u
r
r
en
cy
is
ch
o
s
en
r
an
d
o
m
ly
,
a
n
d
th
e
o
wn
er
o
f
th
at
m
o
n
ey
ca
n
attac
h
it
to
th
e
b
lo
ck
c
h
ai
n
an
d
th
er
e
-
f
o
r
e
co
llect
a
b
lo
ck
r
ewa
r
d
.
User
s
’
s
tak
es
o
f
c
o
in
s
co
n
tr
ib
u
te
d
ar
e
r
ed
u
ce
d
,
an
d
u
s
er
s
ar
e
p
en
alis
ed
if
th
ey
o
f
f
e
n
d
wh
e
n
co
n
t
r
ib
u
tin
g
a
b
l
o
ck
to
t
h
e
s
y
s
tem
[
1
4
].
Per
m
is
s
io
n
ed
b
lo
ck
ch
ain
co
n
s
en
s
u
s
:
o
n
ly
k
n
o
wn
p
ar
ties
ca
n
p
ar
ticip
ate
in
th
e
c
o
n
s
en
s
u
s
t
o
co
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1
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1
9
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[
2
1
]
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(
C
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[
2
2
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tific
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tio
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b
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all
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th
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th
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n
am
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t
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tr
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a
CA
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wh
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will
b
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2
3
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th
e
lo
s
s
o
f
its
p
r
iv
ate
d
o
cu
m
en
ts
.
T
h
is
cr
ea
tes
o
p
p
o
r
tu
n
ities
f
o
r
tr
u
s
ted
p
r
o
f
e
s
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io
n
als
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d
in
s
tr
u
cto
r
s
to
g
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ce
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tific
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d
id
e
n
tific
atio
n
s
in
a
c
o
o
r
d
i
n
ated
m
an
n
er
.
T
h
e
b
lo
ck
c
h
ain
g
i
v
es
tr
a
n
s
p
ar
en
t
p
r
o
o
f
t
h
at
a
r
eg
u
latin
g
p
e
r
s
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n
ality
f
u
n
d
ed
an
u
n
d
er
s
tu
d
y
p
er
s
o
n
ality
,
b
u
t
it
d
o
es
n
o
t
co
n
f
ir
m
eith
e
r
p
a
r
ty
’
s
tr
u
s
two
r
th
in
ess
in
an
d
o
f
its
elf
.
T
h
e
b
l
o
c
k
ch
ain
ca
n
q
u
ick
ly
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d
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eliab
ly
v
alid
ate
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e
e
x
is
ten
ce
o
f
a
n
ac
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ity
,
s
u
ch
as th
e
is
s
u
an
ce
o
f
a
ce
r
tifi
-
ca
te,
b
u
t n
o
t its
leg
itima
cy
.
Ver
if
icatio
n
o
f
s
m
ar
t
co
n
tr
ac
t
s
:
b
lo
ck
ch
ain
tech
n
o
l
o
g
y
en
a
b
les
a
d
is
tr
ib
u
ted
co
m
p
u
tin
g
s
y
s
tem
in
wh
ich
th
e
p
ar
ticip
an
ts
co
n
cu
r
o
n
a
s
in
g
le
h
is
to
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y
o
f
tr
an
s
ac
tio
n
s
,
m
ak
in
g
th
e
tr
an
s
ac
tio
n
s
p
u
b
lic.
Af
ter
b
e
-
in
g
d
iv
id
ed
i
n
to
b
lo
ck
s
an
d
g
i
v
e
n
tim
estam
p
s
,
th
e
tr
a
n
s
ac
tio
n
s
ar
e
p
u
b
lis
h
ed
.
E
ac
h
b
l
o
ck
’
s
h
ash
b
u
ild
s
o
n
th
e
Evaluation Warning : The document was created with Spire.PDF for Python.
I
n
d
o
n
esian
J
E
lec
E
n
g
&
C
o
m
p
Sci
I
SS
N:
2502
-
4
7
5
2
C
r
yp
to
g
r
a
p
h
ica
lly
s
ec
u
r
e
d
ig
ita
l c
erti
fica
tes o
n
a
d
is
tr
ib
u
ted
led
g
er
(
Umn
a
I
ftikh
a
r
)
241
p
r
ev
io
u
s
b
lo
ck
’
s
h
ash
to
cr
e
ate
a
ch
ain
,
m
a
k
in
g
it
ch
alle
n
g
in
g
to
c
h
an
g
e
p
u
b
lis
h
ed
b
lo
ck
s
.
T
h
e
u
s
e
o
f
b
lo
ck
ch
ain
tech
n
o
lo
g
y
is
h
o
w
co
m
p
u
ter
s
y
s
tem
s
c
an
co
n
tr
o
l
h
o
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wo
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ld
p
ar
ties
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ter
a
ct
with
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n
e
an
o
t
h
e
r
in
m
an
y
d
if
f
e
r
en
t
way
s
.
T
h
e
p
r
er
eq
u
is
ites
f
o
r
th
e
in
v
o
lv
em
en
t
o
f
r
eliab
le
ce
n
tr
al
au
th
o
r
it
ies
o
r
th
e
u
s
ag
e
o
f
r
eso
u
r
ce
m
an
a
g
er
s
r
estricte
d
th
e
ad
o
p
tio
n
o
f
s
m
ar
t
c
o
n
tr
ac
ts
o
n
th
e
b
lo
c
k
ch
ain
.
Sp
ec
if
ic
B
lo
ck
ch
ain
s
y
s
tem
s
’
im
p
licit e
n
f
o
r
ce
m
e
n
t o
f
s
m
ar
t
co
n
tr
ac
ts
h
as c
r
ea
te
d
wea
lth
o
f
n
ew
p
o
s
s
ib
ilit
ies [
2
4
]
.
Dep
lo
y
m
en
t
o
f
s
m
ar
t
c
o
n
tr
ac
t
:
t
h
e
v
er
if
ied
co
n
tr
ac
ts
ca
n
b
e
im
p
lem
en
ted
o
n
t
h
e
p
latf
o
r
m
o
n
to
p
o
f
b
lo
ck
ch
ain
s
.
T
h
o
s
e
wh
o
s
to
r
e
co
n
tr
ac
ts
o
n
b
lo
ck
ch
ai
n
s
ca
n
n
o
t.
B
ec
au
s
e
b
lo
ck
ch
ain
s
a
r
e
im
m
u
tab
le,
th
ey
ca
n
n
o
t
b
e
ch
an
g
ed
.
A
n
ew
co
n
tr
ac
t
m
u
s
t
b
e
wr
itten
f
o
r
ea
ch
am
en
d
m
en
t.
T
h
e
co
n
-
tr
ac
ts
ar
e
ac
ce
s
s
ib
le
to
al
l
p
ar
ties
v
ia
th
e
B
lo
ck
ch
ain
s
af
ter
th
e
im
p
lem
e
n
tatio
n
o
f
s
m
ar
t
co
n
tr
ac
ts
.
Ad
d
itio
n
ally
,
b
o
th
p
ar
t
ies
ar
e
in
v
o
lv
ed
.
T
h
e
s
m
ar
t
co
n
tr
ac
t
l
o
ck
s
th
e
p
ar
ties
b
y
f
r
ee
zin
g
t
h
e
eq
u
iv
alen
t
d
ig
ital
wallets.
Fo
r
illu
s
tr
atio
n
,
th
e
co
in
o
n
t
h
e
wallets,
tr
an
s
f
er
s
ca
n
b
e
m
ad
e
in
war
d
a
n
d
o
u
tb
o
u
n
d
.
B
lo
ck
in
g
wo
r
d
s
th
at
p
e
r
tain
to
th
e
co
n
tr
ac
t.
Ho
wev
er
,
th
e
Par
ties
’
d
ig
i
tal
wallets
ca
n
b
e
u
s
ed
to
id
en
tify
th
em
[
2
5
]
.
I
n
Fig
u
r
e
2
th
r
o
u
g
h
a
s
u
itab
le
web
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r
o
wser
o
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th
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b
u
ilt
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in
b
r
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o
f
th
e
m
o
b
ile
ap
p
,
Me
taM
ask
en
a
b
les
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s
er
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to
s
af
ely
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n
n
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t
to
d
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e
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tr
alis
ed
ap
p
licatio
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,
s
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e
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ac
co
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t
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d
ca
s
t
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an
s
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it
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d
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e
E
th
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m
-
b
ase
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m
o
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d
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r
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ast
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a
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ct
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o
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.
I
t
s
h
o
w
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as
e
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e
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e
q
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Fig
u
r
e
2
.
Dep
l
o
y
m
en
t
p
r
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ce
s
s
f
o
r
a
s
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ar
t c
o
n
tr
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t,
a
p
iv
o
tal
asp
ec
t o
f
b
lo
c
k
ch
ain
tech
n
o
lo
g
y
Z
er
o
-
k
n
o
wled
g
e
p
r
o
o
f
:
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ze
r
o
-
k
n
o
wled
g
e
s
tatem
en
t
p
r
o
t
o
co
l
in
c
r
y
p
to
g
r
ap
h
y
is
h
o
w
o
n
e
p
er
s
o
n
(
p
r
o
o
f
o
f
claim
)
ca
n
v
er
if
y
th
e
o
th
er
en
tity
(
v
alid
ato
r
)
th
at
th
e
s
p
ec
if
ic
in
f
o
r
m
atio
n
is
ac
cu
r
ate.
At
th
e
s
am
e
tim
e,
th
e
o
n
e
th
at
p
r
o
v
es
d
o
e
s
n
o
t
tr
an
s
f
er
ev
er
y
ad
d
itio
n
a
l
d
ata
o
th
er
th
a
n
th
e
f
ac
t
th
at
th
e
d
ata
is
co
r
r
ec
t.
T
h
e
p
r
em
is
e
o
f
ze
r
o
-
k
n
o
wled
g
e
ar
g
u
m
en
ts
is
s
tr
aig
h
t
f
o
r
war
d
to
d
em
o
n
s
tr
ate
k
n
o
wled
g
e
o
f
s
o
m
e
i
n
f
o
r
m
atio
n
s
im
p
ly
b
y
d
is
clo
s
in
g
t
h
e
s
itu
at
io
n
.
Ver
if
y
in
g
s
u
ch
in
f
o
r
m
atio
n
with
o
u
t
r
elea
s
in
g
t
h
e
tr
u
th
o
r
a
d
d
itio
n
al
d
ata
is
th
e
p
r
o
b
lem
[
2
6
]
.
T
h
e
ze
r
o
-
k
n
o
wled
g
e
p
r
o
o
f
s
y
s
tem
is
a
cr
u
cial
ar
ea
o
f
co
m
p
u
tatio
n
al
co
m
p
lex
ity
th
eo
r
y
an
d
cr
y
p
to
g
r
ap
h
y
th
at
h
as
attr
ac
te
d
a
lo
t
o
f
atten
tio
n
s
in
ce
it
w
as
f
ir
s
t
p
r
esen
ted
.
A
s
in
g
le
co
m
m
u
n
icatio
n
f
r
o
m
th
e
p
r
o
v
er
to
th
e
v
er
if
ie
r
is
all
th
at
is
co
n
tain
ed
in
a
n
o
n
-
im
m
er
s
iv
e
ze
r
o
-
k
n
o
wled
g
e
p
r
o
o
f
s
y
s
tem
.
I
t
is
f
r
eq
u
e
n
tly
em
p
lo
y
e
d
in
cr
ea
tin
g
n
u
m
er
o
u
s
cr
y
p
to
-
g
r
ap
h
i
c
p
r
o
to
co
ls
an
d
alg
o
r
it
h
m
s
d
u
e
to
its
s
tr
o
n
g
au
th
en
ticatio
n
,
d
ec
en
t p
r
iv
ac
y
,
a
n
d
lo
w
in
ter
ac
tiv
e
co
m
p
le
x
ity
[
2
7
]
.
Hash
f
u
n
ctio
n
:
a
h
ash
f
u
n
ctio
n
ca
n
b
e
d
ef
i
n
ed
as
tak
i
n
g
a
n
in
p
u
t
v
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e
an
d
g
en
e
r
atin
g
a
p
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ed
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o
u
tp
u
t
v
al
u
e
b
ased
o
n
t
h
at
in
p
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t
v
alu
e.
W
h
en
ex
ec
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tin
g
th
e
h
ash
,
th
e
o
u
tp
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t
will
alwa
y
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am
e
Y
f
in
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o
u
tp
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t
f
o
r
wh
ate
v
er
X
in
p
u
t
v
alu
e
[
2
8
]
.
E
ac
h
in
p
u
t
h
as
a
p
r
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d
eter
m
i
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ed
o
u
tp
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in
th
is
m
an
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er
.
Dep
icts
th
e
s
itu
atio
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,
as
a
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esu
lt,
a
h
ash
f
u
n
ctio
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tak
es
in
-
p
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a
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ash
.
A
h
ex
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d
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al
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m
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is
co
m
m
o
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l
y
u
s
ed
to
r
ep
r
esen
t
a
h
ash
[
1
8
]
.
T
h
er
e
ar
e
o
th
er
h
a
s
h
es
alg
o
r
ith
m
s
,
s
u
ch
as
(
MD
,
an
d
SHA)
,
wh
ich
ar
e
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e
m
o
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t
w
id
ely
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s
ed
h
as
h
f
u
n
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s
.
Hash
f
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n
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a
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ally
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(
o
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e
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)
,
wh
ich
im
p
lies
th
at
if
y
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ly
k
n
o
w
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e
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u
t
p
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t,
y
o
u
wo
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t
b
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ab
le
to
f
in
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o
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e
in
p
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t
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n
less
y
o
u
test
ev
er
y
p
o
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s
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le
in
p
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t
[
2
9
]
.
Fig
u
r
e
3
illu
s
tr
ates
a
cr
y
p
to
g
r
ap
h
ic
p
r
o
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ter
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ates
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ile
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et
ails
o
f
th
e
in
f
o
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m
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ei
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g
v
er
if
ied
[
3
0
]
.
B
y
en
s
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r
in
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at
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co
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f
id
en
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in
th
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ata’
s
ac
cu
r
ac
y
[
31
].
Evaluation Warning : The document was created with Spire.PDF for Python.
I
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I
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J
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&
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p
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,
Vo
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40
,
No
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1
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er
20
25
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236
-
2
6
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242
Fig
u
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e
3
.
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cr
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2.
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ically
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.
A
f
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ca
s
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n
f
ir
m
t
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ap
p
en
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d
in
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ea
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s
,
as w
ith
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th
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ca
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ig
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etts
estab
li
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ed
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in
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)
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o
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ce
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in
s
tr
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e
q
u
alif
icatio
n
s
f
o
r
2
8
a
lo
n
g
tim
e
[
3
2
]
.
I
n
th
is
s
et
tin
g
,
a
u
n
iv
er
s
ally
r
ec
o
g
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ize
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if
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tific
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(
as
tr
an
s
cr
ip
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,
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d
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)
an
d
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ch
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last
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q
u
alif
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a
m
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s
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B
esid
es
p
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v
i
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in
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li
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co
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ir
m
atio
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ity
a
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v
er
if
icati
o
n
o
f
co
m
p
eten
cies.
Op
e
n
B
ad
g
e
[
3
3
]
.
T
h
e
s
co
p
e
o
f
Op
e
n
B
ad
g
e
is
to
p
r
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-
v
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an
izatio
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to
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to
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ize
n
o
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as
if
it
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e
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ei
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b
u
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ee
d
t
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s
v
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-
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ap
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Fo
r
th
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s
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,
ce
r
tific
ates
co
m
p
lian
t
with
Op
en
I
d
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tific
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s
ar
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p
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n
n
ed
to
p
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a
p
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in
t
-
by
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p
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in
t
p
r
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f
ile
o
f
th
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en
e
f
iciar
y
,
in
clu
d
in
g
t
h
e
s
o
-
ca
lled
Dip
lo
m
a
Su
p
p
lem
en
t
[
3
4
]
.
T
h
e
E
u
r
o
p
ea
n
Data
Scien
ce
Aca
d
em
y
(
E
DSA)
[
3
5
]
m
ay
b
e
an
e
x
ce
llen
t
ex
am
p
le
o
f
b
l
o
ck
ch
ain
in
n
o
v
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b
ei
n
g
u
s
ed
to
p
r
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v
id
e
in
f
o
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m
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s
cien
ce
s
k
ills
to
jo
b
s
ee
k
er
s
.
E
DSA,
to
o
,
m
a
k
es
a
d
if
f
er
en
ce
b
y
p
r
o
v
id
i
n
g
tr
ain
i
n
g
to
wo
r
ld
-
lead
in
g
in
f
o
r
m
atio
n
s
cien
-
tis
ts
in
th
e
m
o
d
er
n
d
ay
.
I
n
f
o
r
m
atio
n
is
b
ein
g
p
r
o
d
u
ce
d
at
an
in
cr
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d
ib
le
r
ate
f
r
o
m
al
l
en
-
ter
p
r
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in
th
e
twen
ty
-
f
ir
s
t
ce
n
tu
r
y
,
p
o
s
in
g
s
ev
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is
s
u
es
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eg
ar
d
i
n
g
d
ata
co
llectio
n
,
ca
-
p
ac
ity
,
a
n
d
a
n
a
ly
s
is
.
Ho
wev
er
,
as
th
e
a
m
o
u
n
t
o
f
in
f
o
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m
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n
av
ailab
le
g
r
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ws,
s
o
d
o
es
th
e
d
em
an
d
f
o
r
p
r
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f
ess
io
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als
with
th
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n
ec
ess
ar
y
s
k
ills
to
s
u
p
er
v
is
e
an
d
g
o
v
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n
it.
As
a
r
esu
lt
o
f
th
is
r
eq
u
ir
em
en
t,
th
e
E
DSA
was
e
s
tab
lis
h
ed
to
p
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o
v
id
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a
p
latf
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r
m
f
o
r
m
o
n
ito
r
in
g
th
e
p
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ce
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s
an
d
co
n
s
u
m
er
s
o
f
in
f
o
r
m
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s
y
s
tem
s
s
p
ec
iali
s
ts
b
y
p
r
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v
id
i
n
g
r
ea
l
-
tim
e
e
x
-
p
er
tis
e
p
r
e
p
ar
atio
n
.
L
ea
r
n
er
-
C
en
ter
ed
B
lo
ck
ch
ain
o
f
O
p
en
U
n
iv
er
s
ity
in
U.
K.
T
h
e
O
p
en
U
n
iv
er
s
ity
o
f
t
h
e
Un
ited
Kin
g
d
o
m
[
3
6
]
Usi
n
g
b
lo
c
k
ch
ain
tech
n
o
lo
g
y
,
a
lear
n
er
ce
n
t
r
ed
ap
p
r
o
ac
h
to
lear
n
i
n
g
h
as
b
ee
n
s
p
r
ea
d
.
T
h
ey
d
em
o
n
s
tr
ated
a
b
eg
in
n
er
en
v
ir
o
n
m
e
n
t
u
s
in
g
b
lo
ck
c
h
ain
in
th
at
p
ap
er
.
T
h
e
s
tu
d
en
t,
in
s
tr
u
cto
r
,
co
u
r
s
es,
teac
h
in
g
f
ab
r
ic,
v
alid
atio
n
s
y
s
tem
,
an
d
lear
n
er
’
s
ass
o
ciatio
n
ar
e
all
in
clu
d
ed
in
th
is
b
io
lo
g
ical
s
y
s
tem
.
T
h
e
s
tu
d
en
ts
ar
e
en
r
o
lled
i
n
v
ar
io
u
s
co
u
r
s
es
an
d
ac
ce
s
s
ad
d
itio
n
al
lear
n
in
g
r
eso
u
r
ce
s
.
Me
n
to
r
s
an
d
o
t
h
er
in
s
tr
u
ctio
n
al
p
er
-
s
o
n
n
el
p
r
o
v
i
d
e
in
f
o
r
m
al
an
d
f
o
r
m
al
a
d
v
ic
e
as
p
ar
t
o
f
th
e
lear
n
er
’
s
en
ti
r
e
s
u
m
m
it
an
d
d
e
-
v
elo
p
m
en
tal
e
v
alu
atio
n
.
C
en
tr
al
r
eg
u
lato
r
y
o
r
g
an
izatio
n
s
g
iv
e
o
f
f
icial
ce
r
tific
atio
n
s
in
d
i
-
ca
tin
g
th
at
t
h
eir
in
s
titu
tio
n
al
p
r
o
ce
s
s
es
h
av
e
b
ee
n
ag
r
e
ed
u
p
o
n
.
E
ac
h
lea
r
n
e
r
h
as
a
n
id
e
n
-
tity
a
n
d
ac
h
iev
e
m
en
t
v
is
u
aliza
tio
n
ar
ea
ca
lled
a
v
is
a,
wh
ich
m
ay
b
e
u
tili
ze
d
in
s
tead
o
f
a
tr
ad
itio
n
al
r
esu
m
e
to
s
h
o
w
th
e
b
o
s
s
h
is
o
r
h
er
ab
ilit
ies.
T
r
an
s
p
ar
en
c
y
,
tr
u
s
t,
s
af
ety
,
a
n
d
s
ec
u
r
ity
ar
e
all
p
r
o
v
i
d
ed
b
y
t
h
is
ar
ch
itectu
r
e.
I
n
U.
C
.
Dav
is
’
s
C
o
m
p
u
te
r
ized
I
d
e
n
tific
atio
n
S
y
s
tem
,
th
ese
f
u
n
d
am
e
n
tal
co
m
p
eten
cies
ar
e
p
r
esen
ted
as
a
’
d
ig
ital
b
ad
g
e’
[
3
7
]
,
th
e
r
e
ar
e
f
iv
e
le
v
els
to
ea
c
h
c
o
m
p
et
en
cy
:
ap
titu
d
e,
i
n
f
o
r
m
atio
n
,
h
o
n
o
r
,
in
v
o
lv
em
en
t
,
an
d
co
m
p
eten
ce
.
T
h
e
’
d
ig
ital
b
ad
g
e’
f
r
am
ewo
r
k
is
a
h
u
m
a
n
ca
p
ital
ass
ess
m
en
t
m
eth
o
d
o
lo
g
y
th
at
v
alid
ates
th
e
co
r
e
co
m
p
eten
cies w
ith
in
t
h
e
p
o
r
ta
b
le
co
n
n
ec
ted
s
o
ciety
ar
e
ea
s
y
an
d
s
tr
aig
h
tf
o
r
war
d
.
Mic
r
o
s
o
f
t
E
x
am
an
d
C
er
tific
atio
n
B
ad
g
e
Mic
r
o
s
o
f
t
team
e
d
u
p
with
Pear
s
o
n
VUE
’
s
R
ec
o
g
n
itio
n
s
tag
e
to
p
r
o
v
id
e
a
u
n
iq
u
e
id
e
n
tifie
r
f
o
r
ce
r
tific
atio
n
p
u
r
ch
a
s
es
.
A
Mic
r
o
s
o
f
t
ce
r
tific
atio
n
s
tam
p
,
av
ailab
le
o
n
th
e
in
ter
n
et
an
d
co
n
tain
in
g
p
h
o
to
s
a
n
d
u
n
iq
u
e
m
etad
ata
ab
o
u
t
th
e
ce
r
tific
ate
h
o
l
d
er
,
co
u
ld
b
e
u
s
ed
as
id
en
tific
atio
n
.
T
h
e
id
e
n
tific
atio
n
p
r
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[
3
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T
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243
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ased
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