<s>
Namecoin	B-Protocol
(	O
Abbreviation	O
:	O
NMC	O
;	O
sign	O
:	O
)	O
is	O
a	O
cryptocurrency	O
originally	O
forked	O
from	O
bitcoin	B-Protocol
software	O
.	O
</s>
<s>
Like	O
bitcoin	B-Protocol
,	O
it	O
is	O
limited	O
to	O
21million	O
.	O
</s>
<s>
Namecoin	B-Protocol
can	O
store	O
data	O
within	O
its	O
own	O
blockchain	B-Application
transaction	I-Application
database	I-Application
.	O
</s>
<s>
The	O
original	O
proposal	O
for	O
Namecoin	B-Protocol
called	O
for	O
Namecoin	B-Protocol
to	O
insert	O
data	O
into	O
bitcoin	B-Protocol
's	O
blockchain	B-Application
directly	O
.	O
</s>
<s>
Anticipating	O
scaling	O
difficulties	O
with	O
this	O
approach	O
,	O
a	O
shared	O
proof-of-work	O
system	O
was	O
proposed	O
to	O
secure	O
new	O
cryptocurrencies	O
with	O
different	O
use	B-Architecture
cases	I-Architecture
.	O
</s>
<s>
Namecoin	B-Protocol
's	O
flagship	O
use	B-Architecture
case	I-Architecture
is	O
the	O
censorship-resistant	O
top	O
level	O
domain	O
.bit	B-Protocol
,	O
which	O
is	O
functionally	O
similar	O
to	O
.com	O
or	O
.net	B-Application
domains	O
but	O
is	O
independent	O
of	O
the	O
Internet	B-Application
Corporation	I-Application
for	I-Application
Assigned	I-Application
Names	I-Application
and	I-Application
Numbers	I-Application
,	O
the	O
main	O
governing	O
body	O
for	O
domain	O
names	O
.	O
</s>
<s>
As	O
of	O
2019	O
,	O
OpenNIC	B-Protocol
no	O
longer	O
supports	O
the	O
.bit	B-Protocol
domain	O
.	O
</s>
<s>
A	O
peer-to-peer	O
network	O
similar	O
to	O
handles	O
Namecoin	B-Protocol
's	O
transactions	O
,	O
balances	O
and	O
issuance	O
through	O
a	O
based	O
proof-of-work	O
scheme	O
(	O
they	O
are	O
issued	O
when	O
a	O
small	O
enough	O
hash	B-Algorithm
value	O
is	O
found	O
,	O
at	O
which	O
point	O
a	O
block	O
is	O
created	O
)	O
.	O
</s>
<s>
Each	O
Namecoin	B-Protocol
record	O
consists	O
of	O
a	O
name	O
and	O
a	O
value	O
.	O
</s>
<s>
The	O
key	O
d/example	O
signifies	O
a	O
record	O
stored	O
in	O
the	O
DNS	B-Application
namespace	O
d	O
with	O
the	O
name	O
example	O
and	O
corresponds	O
to	O
the	O
record	O
for	O
the	O
example.bit	O
website	O
.	O
</s>
<s>
The	O
content	O
of	O
d/example	O
is	O
expected	O
to	O
conform	O
to	O
the	O
DNS	B-Application
namespace	O
specification.	O
,	O
the	O
fee	O
for	O
a	O
record	O
was	O
0.01	O
NMC	O
and	O
records	O
expired	O
after	O
36000	O
blocks	O
(	O
~	O
200	O
days	O
)	O
unless	O
updated	O
or	O
renewed	O
.	O
</s>
<s>
.bit	B-Protocol
is	O
a	O
top-level	O
domain	O
,	O
created	O
outside	O
the	O
commonly	O
used	O
Domain	B-Protocol
Name	I-Protocol
System	I-Protocol
,	O
and	O
is	O
not	O
sanctioned	O
by	O
ICANN	B-Application
.	O
</s>
<s>
The	O
.bit	B-Protocol
domain	O
is	O
served	O
via	O
Namecoin	B-Protocol
infrastructure	O
,	O
which	O
acts	O
as	O
a	O
decentralized	O
domain	B-Protocol
name	I-Protocol
system	I-Protocol
.	O
</s>
<s>
Proposed	O
potential	O
uses	O
for	O
Namecoin	B-Protocol
besides	O
domain	O
name	O
registration	O
include	O
notary/timestamp	O
systems	O
.	O
</s>
<s>
In	O
September	O
2010	O
,	O
a	O
discussion	O
was	O
started	O
in	O
the	O
BitcoinTalk	O
forum	O
about	O
a	O
hypothetical	O
system	O
called	O
BitDNS	O
and	O
generalizing	O
bitcoin	B-Protocol
.	O
</s>
<s>
On	O
block	O
19200	O
Namecoin	B-Protocol
activated	O
the	O
merged	O
mining	O
upgrade	O
to	O
allow	O
mining	O
of	O
Bitcoin	B-Protocol
and	O
Namecoin	B-Protocol
simultaneously	O
,	O
instead	O
of	O
having	O
to	O
choose	O
between	O
one	O
or	O
the	O
other	O
;	O
this	O
fixed	O
the	O
issue	O
of	O
miners	O
jumping	O
from	O
one	O
blockchain	B-Application
to	O
another	O
when	O
the	O
profitability	O
becomes	O
favorable	O
in	O
the	O
former	O
.	O
</s>
<s>
NameID	O
allows	O
to	O
associate	O
profile	O
information	O
with	O
identities	O
on	O
the	O
Namecoin	B-Protocol
blockchain	B-Application
,	O
and	O
an	O
OpenID	O
provider	O
to	O
allow	O
logging	O
into	O
existing	O
websites	O
with	O
Namecoin	B-Protocol
identities	O
.	O
</s>
<s>
The	O
main	O
site	O
itself	O
is	O
accompanied	O
by	O
an	O
open	O
protocol	O
for	O
password-less	O
authentication	O
with	O
Namecoin	B-Protocol
identities	O
,	O
a	O
corresponding	O
free-software	B-Application
implementation	O
and	O
a	O
supporting	O
extension	B-Protocol
for	O
Firefox	B-Application
.	O
</s>
<s>
In	O
October	O
2013	O
,	O
Michael	O
Gronager	O
,	O
main	O
developer	O
of	O
libcoin	O
,	O
found	O
a	O
security	O
issue	O
in	O
the	O
Namecoin	B-Protocol
protocol	O
,	O
which	O
allowed	O
modifying	O
foreign	O
names	O
.	O
</s>
<s>
It	O
was	O
successfully	O
fixed	O
in	O
a	O
short	O
timeframe	O
and	O
was	O
never	O
exploited	O
,	O
except	O
for	O
bitcoin.bit	O
as	O
a	O
proof-of-concept	O
.	O
</s>
<s>
Namecoin	B-Protocol
was	O
also	O
mentioned	O
by	O
ICANN	B-Application
in	O
a	O
public	O
report	O
as	O
the	O
most	O
well-known	O
example	O
of	O
distributing	O
control	O
and	O
privacy	O
in	O
DNS	B-Application
.	O
</s>
<s>
A	O
2015	O
study	O
found	O
that	O
of	O
the	O
120,000	O
domain	O
names	O
registered	O
on	O
Namecoin	B-Protocol
,	O
only	O
28	O
were	O
in	O
use	O
.	O
</s>
<s>
In	O
December	O
2018	O
,	O
a	O
proposal	O
was	O
tabled	O
on	O
the	O
OpenNIC	B-Protocol
mailing	O
list	O
to	O
drop	O
support	O
for	O
Namecoin	B-Protocol
.bit	B-Protocol
domains.	O
,	O
citing	O
Spamhaus	O
 '	O
(	O
and	O
by	O
extension	B-Protocol
other	O
antivirus	B-Application
software	I-Application
)	O
blocking	O
of	O
several	O
of	O
their	O
servers	O
owing	O
to	O
spread	O
of	O
malware	O
from	O
some	O
.bit	B-Protocol
domains	O
,	O
as	O
well	O
as	O
concerns	O
about	O
potential	O
child	O
pornography	O
.	O
</s>
<s>
In	O
the	O
same	O
month	O
,	O
OpenNIC	B-Protocol
was	O
advised	O
to	O
drop	O
support	O
for	O
.bit	B-Protocol
namespace	O
owing	O
to	O
security	O
concerns	O
of	O
Namecoin	B-Protocol
and	O
PRISM	O
Break	O
developers	O
.	O
</s>
<s>
In	O
July	O
2019	O
,	O
OpenNIC	B-Protocol
again	O
voted	O
on	O
dropping	O
the	O
.bit	B-Protocol
namespace	O
,	O
citing	O
"	O
numerous	O
problems	O
with	O
support	O
of	O
NameCoin	B-Protocol
domains	O
"	O
and	O
recent	O
animosity	O
between	O
the	O
two	O
projects	O
.	O
</s>
<s>
Namecoin	B-Protocol
developer	O
Jeremy	O
Rand	O
welcomed	O
the	O
move	O
,	O
thanking	O
OpenNIC	B-Protocol
and	O
describing	O
it	O
as	O
the	O
"	O
right	O
decision	O
"	O
.	O
</s>
