<s>
Whisper	B-Application
Systems	I-Application
was	O
an	O
American	O
enterprise	O
mobile	O
security	O
company	O
that	O
was	O
co-founded	O
by	O
security	O
researcher	O
Moxie	O
Marlinspike	O
and	O
roboticist	O
Stuart	O
Anderson	O
in	O
2010	O
.	O
</s>
<s>
The	O
company	O
was	O
acquired	O
by	O
Twitter	B-Application
in	O
November	O
2011	O
.	O
</s>
<s>
An	O
independent	O
group	O
called	O
Open	O
Whisper	B-Application
Systems	I-Application
later	O
picked	O
up	O
the	O
development	O
of	O
this	O
open-source	O
software	O
,	O
which	O
led	O
to	O
the	O
creation	O
of	O
the	O
Signal	B-Application
Technology	O
Foundation	O
.	O
</s>
<s>
Security	O
researcher	O
Moxie	O
Marlinspike	O
and	O
roboticist	O
Stuart	O
Anderson	O
co-founded	O
Whisper	B-Application
Systems	I-Application
in	O
2010	O
.	O
</s>
<s>
The	O
company	O
produced	O
proprietary	B-Application
enterprise	O
mobile	O
security	O
software	O
.	O
</s>
<s>
Among	O
these	O
were	O
an	O
encrypted	O
texting	O
program	O
called	O
TextSecure	B-Protocol
and	O
an	O
encrypted	O
voice	O
calling	O
app	O
called	O
RedPhone	O
.	O
</s>
<s>
On	O
November	O
28	O
,	O
2011	O
,	O
Whisper	B-Application
Systems	I-Application
announced	O
that	O
it	O
had	O
been	O
acquired	O
by	O
Twitter	B-Application
.	O
</s>
<s>
Shortly	O
after	O
the	O
acquisition	O
,	O
Whisper	B-Application
Systems	I-Application
 '	O
RedPhone	O
service	O
was	O
made	O
unavailable	O
.	O
</s>
<s>
Twitter	B-Application
released	O
TextSecure	B-Protocol
as	O
free	B-License
and	I-License
open-source	I-License
software	I-License
under	O
the	O
GPLv3	B-License
license	O
in	O
December	O
2011	O
.	O
</s>
<s>
Marlinspike	O
later	O
left	O
Twitter	B-Application
and	O
founded	O
Open	O
Whisper	B-Application
Systems	I-Application
as	O
a	O
collaborative	O
Open	O
Source	O
project	O
for	O
the	O
continued	O
development	O
of	O
TextSecure	B-Protocol
and	O
RedPhone	O
.	O
</s>
<s>
Open	O
Whisper	B-Application
Systems	I-Application
consisted	O
of	O
a	O
large	O
community	O
of	O
volunteer	O
Open	O
Source	O
contributors	O
,	O
as	O
well	O
as	O
a	O
small	O
team	O
of	O
dedicated	O
grant-funded	O
developers	O
.	O
</s>
<s>
In	O
November	O
2015	O
,	O
Open	O
Whisper	B-Application
Systems	I-Application
merged	O
TextSecure	B-Protocol
with	O
RedPhone	O
and	O
renamed	O
it	O
as	O
Signal	B-Application
.	O
</s>
<s>
In	O
2018	O
,	O
Signal	B-Application
Messenger	I-Application
was	O
incorporated	O
as	O
an	O
LLC	O
by	O
Moxie	O
Marlinspike	O
and	O
Brian	O
Acton	O
and	O
then	O
rolled	O
under	O
the	O
independent	O
non-profit	O
Signal	B-Application
Technology	O
Foundation	O
.	O
</s>
<s>
Today	O
,	O
the	O
Signal	B-Application
app	I-Application
is	O
developed	O
by	O
Signal	B-Application
Messenger	I-Application
LLC	O
,	O
which	O
is	O
funded	O
by	O
the	O
Signal	B-Application
Foundation	O
.	O
</s>
<s>
Whisper	B-Application
Systems	I-Application
 '	O
products	O
were	O
all	O
made	O
for	O
Android	O
and	O
included	O
:	O
</s>
<s>
TextSecure	B-Protocol
:	O
An	O
app	O
that	O
allowed	O
the	O
user	O
to	O
exchange	O
end-to-end	O
encrypted	O
SMS	B-Device
messages	O
with	O
other	O
TextSecure	B-Protocol
users	O
.	O
</s>
<s>
RedPhone	O
:	O
An	O
app	O
that	O
allowed	O
the	O
user	O
to	O
make	O
end-to-end	O
encrypted	O
VoIP	B-Application
calls	I-Application
to	O
other	O
RedPhone	O
users	O
.	O
</s>
<s>
Flashback	O
:	O
An	O
app	O
that	O
allowed	O
the	O
user	O
to	O
store	O
encrypted	O
backups	O
of	O
their	O
device	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
.	O
</s>
<s>
The	O
initial	O
beta	O
featured	O
full	O
disk	O
encryption	O
,	O
network	O
security	O
tools	O
,	O
encrypted	O
backup	O
,	O
selective	O
permissions	O
,	O
and	O
basic	O
platform	O
management	O
tools	O
for	O
Nexus	B-Device
S	I-Device
and	O
Nexus	B-Application
One	I-Application
phones	O
.	O
</s>
<s>
WhisperMonitor	O
:	O
An	O
app	O
that	O
worked	O
with	O
WhisperCore	O
to	O
provide	O
a	O
software	O
firewall	O
capable	O
of	O
dynamic	O
egress	B-Protocol
filtering	I-Protocol
and	O
real-time	O
connection	O
monitoring	O
,	O
giving	O
the	O
user	O
control	O
over	O
where	O
their	O
data	O
was	O
going	O
and	O
what	O
their	O
apps	O
were	O
doing	O
.	O
</s>
