<s>
In	O
cryptography	O
and	O
computer	O
security	O
,	O
a	O
root	B-Protocol
certificate	I-Protocol
is	O
a	O
public	O
key	O
certificate	O
that	O
identifies	O
a	O
root	B-Protocol
certificate	I-Protocol
authority	I-Protocol
(	O
CA	O
)	O
.	O
</s>
<s>
Root	B-Protocol
certificates	I-Protocol
are	O
self-signed	B-Protocol
(	O
and	O
it	O
is	O
possible	O
for	O
a	O
certificate	O
to	O
have	O
multiple	O
trust	O
paths	O
,	O
say	O
if	O
the	O
certificate	O
was	O
issued	O
by	O
a	O
root	O
that	O
was	O
cross-signed	O
)	O
and	O
form	O
the	O
basis	O
of	O
an	O
X.509-based	O
public	B-Architecture
key	I-Architecture
infrastructure	I-Architecture
(	O
PKI	O
)	O
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
PKIs	O
supporting	O
HTTPS	B-Application
for	O
secure	O
web	O
browsing	O
and	O
electronic	O
signature	O
schemes	O
depend	O
on	O
a	O
set	O
of	O
root	B-Protocol
certificates	I-Protocol
.	O
</s>
<s>
A	O
certificate	B-Architecture
authority	I-Architecture
can	O
issue	O
multiple	O
certificates	O
in	O
the	O
form	O
of	O
a	O
tree	B-Data_Structure
structure	I-Data_Structure
.	O
</s>
<s>
A	O
root	B-Protocol
certificate	I-Protocol
is	O
the	O
top-most	O
certificate	O
of	O
the	O
tree	O
,	O
the	O
private	O
key	O
which	O
is	O
used	O
to	O
"	O
sign	O
"	O
other	O
certificates	O
.	O
</s>
<s>
All	O
certificates	O
signed	O
by	O
the	O
root	B-Protocol
certificate	I-Protocol
,	O
with	O
the	O
"	O
CA	O
"	O
field	O
set	O
to	O
true	O
,	O
inherit	O
the	O
trustworthiness	O
of	O
the	O
root	B-Protocol
certificate	I-Protocol
—	O
a	O
signature	O
by	O
a	O
root	B-Protocol
certificate	I-Protocol
is	O
somewhat	O
analogous	O
to	O
"	O
notarizing	O
"	O
identity	O
in	O
the	O
physical	O
world	O
.	O
</s>
<s>
Such	O
a	O
certificate	O
is	O
called	O
an	O
intermediate	O
certificate	O
or	O
subordinate	O
CA	B-Architecture
certificate	I-Architecture
.	O
</s>
<s>
The	O
root	B-Protocol
certificate	I-Protocol
is	O
usually	O
made	O
trustworthy	O
by	O
some	O
mechanism	O
other	O
than	O
a	O
certificate	O
,	O
such	O
as	O
by	O
secure	O
physical	O
distribution	O
.	O
</s>
<s>
For	O
example	O
,	O
some	O
of	O
the	O
best-known	O
root	B-Protocol
certificates	I-Protocol
are	O
distributed	O
in	O
operating	O
systems	O
by	O
their	O
manufacturers	O
.	O
</s>
<s>
Microsoft	O
distributes	O
root	B-Protocol
certificates	I-Protocol
belonging	O
to	O
members	O
of	O
the	O
Microsoft	O
Root	B-Protocol
Certificate	I-Protocol
Program	O
to	O
Windows	O
desktops	O
and	O
Windows	O
Phone	O
8	O
.	O
</s>
<s>
Apple	O
distributes	O
root	B-Protocol
certificates	I-Protocol
belonging	O
to	O
members	O
of	O
its	O
own	O
root	O
program	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
Dutch	O
certificate	B-Architecture
authority	I-Architecture
DigiNotar	O
suffered	O
a	O
security	O
breach	O
.	O
</s>
<s>
In	O
2009	O
,	O
an	O
employee	O
of	O
the	O
China	O
Internet	O
Network	O
Information	O
Center	O
(	O
CNNIC	O
)	O
applied	O
to	O
Mozilla	B-Operating_System
to	O
add	O
CNNIC	O
to	O
Mozilla	B-Operating_System
's	O
root	B-Protocol
certificate	I-Protocol
list	O
and	O
was	O
approved	O
.	O
</s>
<s>
Later	O
,	O
Microsoft	O
also	O
added	O
CNNIC	O
to	O
the	O
root	B-Protocol
certificate	I-Protocol
list	O
of	O
Windows	O
.	O
</s>
<s>
In	O
2015	O
,	O
many	O
users	O
chose	O
not	O
to	O
trust	O
the	O
digital	O
certificates	O
issued	O
by	O
CNNIC	O
because	O
an	O
intermediate	O
CA	O
issued	O
by	O
CNNIC	O
was	O
found	O
to	O
have	O
issued	O
fake	O
certificates	O
for	O
Google	B-Application
domain	O
names	O
and	O
raised	O
concerns	O
about	O
CNNIC	O
's	O
abuse	O
of	O
certificate	O
issuing	O
power	O
.	O
</s>
<s>
On	O
April	O
2	O
,	O
2015	O
,	O
Google	B-Application
announced	O
that	O
it	O
no	O
longer	O
recognized	O
the	O
electronic	O
certificate	O
issued	O
by	O
CNNIC	O
.	O
</s>
<s>
on	O
April	O
4	O
,	O
following	O
Google	B-Application
,	O
Mozilla	B-Operating_System
also	O
announced	O
that	O
it	O
no	O
longer	O
recognized	O
the	O
electronic	O
certificate	O
issued	O
by	O
CNNIC	O
.	O
</s>
<s>
in	O
August	O
2016	O
,	O
the	O
official	O
website	O
of	O
CNNIC	O
had	O
abandoned	O
the	O
root	B-Protocol
certificate	I-Protocol
issued	O
by	O
itself	O
and	O
replaced	O
it	O
with	O
the	O
certificate	O
issued	O
by	O
DigiCert-issued	O
certificate	O
.	O
</s>
<s>
In	O
2016	O
,	O
WoSign	O
,	O
China	O
's	O
largest	O
CA	B-Architecture
certificate	I-Architecture
issuer	O
owned	O
by	O
Qihoo	O
360	O
and	O
its	O
Israeli	O
subsidiary	O
StartCom	O
,	O
were	O
denied	O
recognition	O
of	O
their	O
certificates	O
by	O
Google	B-Application
.	I-Application
</s>
<s>
WoSign	O
and	O
StartCom	O
even	O
issued	O
a	O
fake	O
GitHub	B-Application
certificate	O
.	O
</s>
<s>
Microsoft	O
also	O
said	O
in	O
2017	O
that	O
they	O
would	O
remove	O
the	O
relevant	O
certificates	O
offline	O
,	O
but	O
in	O
February	O
2021	O
users	O
still	O
reported	O
that	O
certificates	O
from	O
WoSign	O
and	O
StartCom	O
were	O
still	O
effective	O
in	O
Windows	B-Operating_System
10	I-Operating_System
and	O
could	O
only	O
be	O
removed	O
manually	O
.	O
</s>
