<s>
An	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
key	O
is	O
a	O
unique	O
identifier	O
used	O
to	O
authenticate	O
and	O
authorize	O
a	O
user	O
,	O
developer	O
,	O
or	O
calling	O
program	O
to	O
an	O
API	B-Application
.	O
</s>
<s>
However	O
,	O
they	O
are	O
typically	O
used	O
to	O
authenticate	O
and	O
authorize	O
a	O
project	O
with	O
the	O
API	B-Application
rather	O
than	O
a	O
human	O
user	O
.	O
</s>
<s>
The	O
API	B-General_Concept
key	I-General_Concept
often	O
acts	O
as	O
both	O
a	O
unique	O
identifier	O
and	O
a	O
secret	O
token	O
for	O
authentication	O
and	O
authorization	O
,	O
and	O
will	O
generally	O
have	O
a	O
set	O
of	O
access	O
rights	O
on	O
the	O
API	B-Application
associated	O
with	O
it	O
.	O
</s>
<s>
API	B-General_Concept
keys	I-General_Concept
for	O
HTTP-based	O
APIs	B-Application
can	O
be	O
sent	O
in	O
multiple	O
ways	O
:	O
</s>
<s>
In	O
the	O
query	O
string:As	O
a	O
request	O
header:As	O
a	O
cookie	B-Application
:	O
</s>
<s>
API	B-General_Concept
keys	I-General_Concept
are	O
generally	O
not	O
considered	O
secure	O
;	O
they	O
are	O
typically	O
accessible	O
to	O
clients	O
,	O
making	O
it	O
easy	O
for	O
someone	O
to	O
steal	O
an	O
API	B-General_Concept
key	I-General_Concept
.	O
</s>
<s>
Since	O
API	B-General_Concept
keys	I-General_Concept
must	O
only	O
be	O
accessible	O
to	O
the	O
client	O
and	O
server	O
,	O
authentication	O
using	O
API	B-General_Concept
keys	I-General_Concept
is	O
only	O
considered	O
secure	O
when	O
used	O
in	O
conjunction	O
with	O
other	O
security	O
mechanisms	O
such	O
as	O
HTTPS	B-Protocol
.	O
</s>
<s>
In	O
2017	O
,	O
Fallible	O
,	O
a	O
Delaware-based	O
security	O
firm	O
examined	O
16,000	O
android	O
apps	O
and	O
identified	O
over	O
300	O
which	O
contained	O
hard-coded	O
API	B-General_Concept
keys	I-General_Concept
for	O
services	O
like	O
Dropbox	O
,	O
Twitter	O
,	O
and	O
Slack	O
.	O
</s>
