<s>
Threema	B-Application
is	O
a	O
paid	B-Application
cross-platform	B-Operating_System
encrypted	O
instant	B-Application
messaging	I-Application
app	O
developed	O
by	O
Threema	B-Application
GmbH	O
in	O
Switzerland	B-Protocol
and	O
launched	O
in	O
2012	O
.	O
</s>
<s>
The	O
service	O
operates	O
on	O
a	O
decentralized	B-Application
architecture	I-Application
and	O
offers	O
end-to-end	O
encryption	O
.	O
</s>
<s>
Users	O
can	O
make	O
voice	O
and	O
video	B-Application
calls	I-Application
,	O
send	O
photos	O
,	O
files	O
,	O
and	O
voice	O
notes	O
,	O
share	O
locations	O
,	O
and	O
make	O
groups	O
.	O
</s>
<s>
Unlike	O
many	O
other	O
popular	O
secure	O
messaging	B-Application
apps	I-Application
,	O
Threema	B-Application
does	O
not	O
require	O
phone	O
numbers	O
or	O
email	O
address	O
for	O
registration	O
,	O
only	O
a	O
one-time	O
purchase	O
.	O
</s>
<s>
Threema	B-Application
is	O
available	O
on	O
iOS	B-Application
and	O
Android	B-Application
and	O
has	O
clients	O
for	O
Windows	B-Application
,	O
macOS	B-Application
,	O
Linux	B-Application
,	O
and	O
can	O
be	O
accessed	O
via	O
web	B-Application
browser	I-Application
but	O
requires	O
a	O
mobile	O
app	O
to	O
function	O
.	O
</s>
<s>
Threema	B-Application
uses	O
a	O
user	O
ID	O
,	O
created	O
after	O
the	O
initial	O
app	O
launch	O
by	O
a	O
random	O
generator	O
,	O
instead	O
of	O
requiring	O
a	O
linked	O
email	O
address	O
or	O
phone	O
number	O
to	O
send	O
messages	O
.	O
</s>
<s>
Linking	O
a	O
phone	O
number	O
or	O
email	O
address	O
to	O
a	O
Threema	B-Application
ID	O
is	O
optional	O
.	O
</s>
<s>
Users	O
can	O
verify	O
the	O
identity	O
of	O
their	O
Threema	B-Application
contacts	O
by	O
scanning	O
their	O
QR	O
code	O
when	O
they	O
meet	O
physically	O
.	O
</s>
<s>
The	O
QR	O
code	O
contains	O
the	O
public	B-Application
key	I-Application
of	O
the	O
user	O
,	O
which	O
is	O
cryptographically	O
tied	O
to	O
the	O
ID	O
and	O
will	O
not	O
change	O
during	O
the	O
lifetime	O
of	O
the	O
identity	O
.	O
</s>
<s>
Using	O
this	O
strong	O
authentication	O
feature	O
,	O
users	O
can	O
make	O
sure	O
they	O
have	O
the	O
correct	O
public	B-Application
key	I-Application
from	O
their	O
chat	O
partners	O
,	O
which	O
provides	O
additional	O
security	O
against	O
a	O
Man-in-the-middle	O
attack	O
.	O
</s>
<s>
Threema	B-Application
knows	O
three	O
levels	O
of	O
authentication	O
(	O
trust	O
levels	O
of	O
the	O
contact	O
's	O
identity	O
)	O
.	O
</s>
<s>
The	O
verification	O
level	O
of	O
each	O
contact	O
is	O
displayed	O
in	O
the	O
Threema	B-Application
application	O
as	O
dots	O
next	O
to	O
the	O
corresponding	O
contact	O
.	O
</s>
<s>
In	O
addition	O
to	O
text	O
messaging	O
,	O
users	O
can	O
make	O
voice	O
and	O
video	B-Application
calls	I-Application
,	O
send	O
multimedia	O
,	O
locations	O
,	O
voice	O
messages	O
,	O
and	O
files	O
.	O
</s>
<s>
A	O
web	B-Application
app	I-Application
version	O
,	O
Threema	B-Application
Web	O
,	O
can	O
be	O
used	O
on	O
desktop	O
devices	O
,	O
but	O
only	O
as	O
long	O
as	O
the	O
phone	O
with	O
the	O
Threema	B-Application
installation	O
of	O
the	O
user	O
is	O
online	O
.	O
</s>
<s>
In	O
addition	O
to	O
one-on-one	O
chats	O
,	O
Threema	B-Application
offers	O
group	O
chats	O
up	O
to	O
256	O
people	O
.	O
</s>
<s>
Users	O
can	O
make	O
voice	O
and	O
video	B-Application
calls	I-Application
,	O
send	O
text	O
and	O
voice	O
messages	O
,	O
multimedia	O
,	O
locations	O
,	O
and	O
files	O
of	O
any	O
type	O
(	O
up	O
to	O
50	O
MB	O
per	O
file	O
)	O
.	O
</s>
<s>
Threema	B-Application
is	O
developed	O
by	O
the	O
Swiss	O
company	O
Threema	B-Application
GmbH	O
.	O
</s>
<s>
The	O
servers	B-Application
are	O
in	O
Switzerland	B-Protocol
and	O
the	O
development	O
is	O
based	O
in	O
Pfäffikon	O
SZ	O
.	O
</s>
<s>
As	O
of	O
May	O
2021	O
,	O
Threema	B-Application
had	O
10	O
million	O
users	O
and	O
the	O
business	O
version	O
,	O
Threema	B-Application
Work	O
,	O
was	O
used	O
by	O
2	O
million	O
users	O
across	O
5,000	O
companies	O
and	O
organizations	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
July	O
,	O
2021	O
Threema	B-Application
introduced	O
the	O
ability	O
for	O
companies	O
to	O
host	O
the	O
messenger	O
on	O
their	O
own	O
server	O
,	O
primarily	O
intended	O
for	O
companies	O
with	O
significantly	O
high	O
privacy	O
concerns	O
.	O
</s>
<s>
With	O
Threema	B-Application
Web	O
,	O
a	O
client	O
for	O
web	B-Application
browsers	I-Application
,	O
Threema	B-Application
can	O
be	O
used	O
from	O
other	O
devices	O
like	O
desktop	B-Device
computers	I-Device
,	O
though	O
only	O
as	O
long	O
as	O
the	O
original	O
device	O
is	O
online	O
.	O
</s>
<s>
Threema	B-Application
optionally	O
supports	O
Android	B-Application
Wear	I-Application
smartwatch	B-Application
and	O
Android	B-Application
Auto	I-Application
.	O
</s>
<s>
Threema	B-Application
launched	O
support	O
for	O
end-to-end	O
encrypted	O
video	B-Application
calls	I-Application
on	O
August	O
10	O
,	O
2020	O
.	O
</s>
<s>
The	O
entire	O
communication	O
via	O
Threema	B-Application
is	O
end-to-end	O
encrypted	O
.	O
</s>
<s>
During	O
the	O
initial	O
setup	O
,	O
the	O
application	O
generates	O
a	O
key	B-Application
pair	I-Application
and	O
sends	O
the	O
public	B-Application
key	I-Application
to	O
the	O
server	O
while	O
keeping	O
the	O
private	B-Application
key	I-Application
on	O
the	O
user	O
's	O
device	O
.	O
</s>
<s>
The	O
application	O
then	O
encrypts	O
all	O
messages	O
and	O
files	O
that	O
are	O
sent	O
to	O
other	O
Threema	B-Application
users	O
with	O
their	O
respective	O
public	B-Application
keys	I-Application
.	O
</s>
<s>
Once	O
a	O
message	O
is	O
delivered	O
successfully	O
,	O
it	O
is	O
immediately	O
deleted	O
from	O
the	O
servers	B-Application
.	O
</s>
<s>
The	O
encryption	O
process	O
used	O
by	O
Threema	B-Application
is	O
based	O
on	O
the	O
open-source	B-Application
library	O
NaCl	B-Application
library	I-Application
.	O
</s>
<s>
Threema	B-Application
uses	O
asymmetric	O
ECC-based	O
encryption	O
,	O
with	O
256-bit	O
strength	O
.	O
</s>
<s>
Threema	B-Application
offers	O
a	O
"	O
Validation	O
Logging	O
"	O
feature	O
that	O
makes	O
it	O
possible	O
to	O
confirm	O
that	O
messages	O
are	O
end-to-end	O
encrypted	O
using	O
the	O
NaCl	B-Application
Networking	O
and	O
Cryptography	O
library	O
.	O
</s>
<s>
In	O
August	O
2015	O
,	O
Threema	B-Application
was	O
subjected	O
to	O
an	O
external	O
security	O
audit	O
.	O
</s>
<s>
Researchers	O
from	O
cnlab	O
confirmed	O
that	O
Threema	B-Application
allows	O
secure	O
end-to-end	O
encryption	O
,	O
and	O
claimed	O
that	O
they	O
were	O
unable	O
to	O
identify	O
any	O
weaknesses	O
in	O
the	O
implementation	O
.	O
</s>
<s>
Cnlab	O
researchers	O
also	O
confirmed	O
that	O
Threema	B-Application
provides	O
anonymity	O
to	O
its	O
users	O
and	O
handles	O
contacts	O
and	O
other	O
user	O
data	O
as	O
advertised	O
.	O
</s>
<s>
Threema	B-Application
was	O
founded	O
in	O
December	O
2012	O
by	O
Manuel	O
Kasper	O
.	O
</s>
<s>
Martin	O
Blatter	O
and	O
Silvan	O
Engeler	O
were	O
later	O
recruited	O
to	O
develop	O
an	O
Android	B-Application
application	I-Application
that	O
was	O
released	O
in	O
early	O
2013	O
.	O
</s>
<s>
In	O
Summer	O
2013	O
,	O
the	O
Snowden	O
leaks	O
helped	O
create	O
an	O
interest	O
in	O
Threema	B-Application
,	O
boosting	O
the	O
user	O
numbers	O
to	O
the	O
hundreds	O
of	O
thousands	O
.	O
</s>
<s>
When	O
Facebook	O
took	O
over	O
WhatsApp	B-Application
in	O
February	O
2014	O
,	O
Threema	B-Application
got	O
200,000	O
new	O
users	O
,	O
doubling	O
its	O
userbase	O
in	O
24	O
hours	O
.	O
</s>
<s>
By	O
March	O
2014	O
Threema	B-Application
had	O
1.2million	O
users	O
.	O
</s>
<s>
In	O
Spring	O
2014	O
,	O
operations	O
were	O
transferred	O
to	O
the	O
newly	O
created	O
Threema	B-Application
GmbH	O
.	O
</s>
<s>
In	O
December	O
2014	O
,	O
Apple	O
listed	O
Threema	B-Application
as	O
the	O
most-sold	O
app	O
of	O
2014	O
at	O
the	O
German	O
App	O
Store	O
.	O
</s>
<s>
In	O
2020	O
,	O
Threema	B-Application
expanded	O
with	O
video	B-Application
calls	I-Application
,	O
plans	O
to	O
open-source	B-Application
its	O
client-side	O
apps	O
and	O
introduce	O
reproducible	O
builds	O
of	O
them	O
,	O
as	O
well	O
as	O
introduce	O
Threema	B-Application
Education	O
,	O
a	O
variation	O
of	O
Threema	B-Application
intended	O
for	O
education	O
institutions	O
.	O
</s>
<s>
During	O
the	O
second	O
week	O
of	O
2021	O
,	O
Threema	B-Application
saw	O
a	O
quadrupling	O
of	O
daily	O
downloads	O
spurred	O
on	O
by	O
controversial	O
privacy	O
changes	O
in	O
the	O
WhatsApp	B-Application
messaging	O
service	O
.	O
</s>
<s>
A	O
spokesperson	O
for	O
the	O
company	O
also	O
confirmed	O
that	O
Threema	B-Application
had	O
risen	O
to	O
the	O
top	O
of	O
the	O
charts	O
for	O
paid	B-Application
applications	O
in	O
Germany	O
,	O
Switzerland	B-Protocol
,	O
and	O
Austria	O
.	O
</s>
<s>
In	O
October	O
2022	O
,	O
researchers	O
from	O
ETH	O
Zurich	O
reported	O
multiple	O
vulnerabilities	O
affecting	O
Threema	B-Application
's	O
security	O
against	O
network	O
,	O
server	O
and	O
client-based	O
attacks	O
.	O
</s>
<s>
Threema	B-Application
Work	O
:	O
On	O
May	O
25	O
,	O
2016	O
,	O
Threema	B-Application
Work	O
,	O
a	O
corporate	O
version	O
of	O
Threema	B-Application
,	O
was	O
released	O
.	O
</s>
<s>
Threema	B-Application
Work	O
offers	O
extended	O
administration	O
and	O
deployment	O
capabilities	O
.	O
</s>
<s>
Threema	B-Application
Work	O
is	O
based	O
on	O
a	O
yearly	O
subscription	O
model	O
.	O
</s>
<s>
Threema	B-Application
Gateway	O
:	O
On	O
March	O
20	O
,	O
2015	O
,	O
Threema	B-Application
released	O
a	O
gateway	O
for	O
companies	O
.	O
</s>
<s>
Similar	O
to	O
an	O
SMS	O
gateway	O
,	O
businesses	O
can	O
use	O
it	O
to	O
send	O
messages	O
to	O
their	O
users	O
who	O
have	O
Threema	B-Application
installed	O
.	O
</s>
<s>
The	O
code	O
for	O
the	O
Threema	B-Application
Gateway	O
SDK	B-Application
is	O
open	O
for	O
developers	O
and	O
available	O
on	O
GitHub	B-Application
.	O
</s>
<s>
Threema	B-Application
Broadcast	O
:	O
On	O
August	O
9	O
,	O
2018	O
,	O
Threema	B-Application
released	O
Threema	B-Application
Broadcast	O
,	O
a	O
tool	O
for	O
top-down	O
communication	O
.	O
</s>
<s>
Similar	O
to	O
emails	O
in	O
electronic	O
newsletters	O
,	O
Threema	B-Application
messages	O
can	O
be	O
sent	O
to	O
any	O
number	O
of	O
feed	O
subscribers	O
,	O
and	O
the	O
Threema	B-Application
Broadcast	O
allows	O
to	O
create	O
chatbots	B-Application
.	O
</s>
<s>
Threema	B-Application
Education	O
:	O
On	O
September	O
10	O
,	O
2020	O
,	O
Threema	B-Application
released	O
Threema	B-Application
Education	O
,	O
a	O
version	O
of	O
its	O
messenger	O
designed	O
for	O
education	O
institutions	O
.	O
</s>
<s>
The	O
app	O
integrates	O
Threema	B-Application
Broadcast	O
and	O
requires	O
a	O
one-time	O
payment	O
for	O
each	O
device	O
used	O
.	O
</s>
<s>
Threema	B-Application
OnPrem	O
:	O
On	O
July	O
27	O
,	O
2021	O
,	O
Threema	B-Application
released	O
Threema	B-Application
OnPrem	O
,	O
a	O
version	O
of	O
the	O
messenger	O
which	O
could	O
be	O
hosted	O
on	O
a	O
company	O
's	O
own	O
servers	B-Application
for	O
maximum	O
security	O
purposes	O
.	O
</s>
<s>
Since	O
Threema	B-Application
's	O
servers	B-Application
are	O
in	O
Switzerland	B-Protocol
,	O
they	O
are	O
subject	O
to	O
the	O
Swiss	O
federal	O
law	O
on	O
data	O
protection	O
.	O
</s>
<s>
Linking	O
a	O
phone	O
number	O
and/or	O
email	O
address	O
to	O
a	O
Threema	B-Application
ID	O
is	O
optional	O
;	O
when	O
doing	O
so	O
,	O
only	O
checksum	B-Algorithm
values	O
(	O
SHA-256	B-Algorithm
HMAC	B-Algorithm
with	O
a	O
static	O
key	O
)	O
of	O
the	O
email	O
address	O
and/or	O
phone	O
number	O
are	O
sent	O
to	O
the	O
server	O
.	O
</s>
<s>
Due	O
to	O
the	O
small	O
number	O
of	O
possible	O
digit	O
combinations	O
of	O
a	O
telephone	O
number	O
,	O
the	O
phone	O
number	O
associated	O
with	O
a	O
checksum	B-Algorithm
could	O
be	O
determined	O
by	O
brute	O
force	O
.	O
</s>
<s>
The	O
transmitted	O
data	O
is	O
TLS-secured	O
.	O
</s>
<s>
The	O
address	O
book	O
data	O
is	O
kept	O
only	O
in	O
the	O
volatile	B-General_Concept
memory	I-General_Concept
of	O
the	O
server	O
and	O
is	O
deleted	O
immediately	O
after	O
synchronizing	O
contacts	O
.	O
</s>
<s>
If	O
a	O
user	O
chooses	O
to	O
link	O
a	O
phone	O
number	O
or	O
email	O
address	O
with	O
their	O
Threema	B-Application
ID	O
,	O
they	O
can	O
remove	O
the	O
phone	O
number	O
or	O
email	O
address	O
at	O
any	O
time	O
.	O
</s>
<s>
Should	O
a	O
user	O
ever	O
lose	O
their	O
device	O
(	O
and	O
their	O
private	B-Application
key	I-Application
)	O
,	O
they	O
can	O
revoke	O
their	O
Threema	B-Application
ID	O
if	O
a	O
revocation	O
password	O
for	O
that	O
ID	O
has	O
been	O
set	O
.	O
</s>
<s>
Groups	O
are	O
solely	O
managed	O
on	O
users’	O
devices	O
and	O
group	O
messages	O
are	O
sent	O
to	O
each	O
recipient	O
as	O
an	O
individual	O
message	O
,	O
encrypted	O
with	O
the	O
respective	O
public	B-Application
key	I-Application
.	O
</s>
<s>
Data	O
(	O
including	O
media	O
files	O
)	O
stored	O
on	O
the	O
users’	O
devices	O
is	O
encrypted	O
with	O
AES	B-Algorithm
256	I-Algorithm
.	O
</s>
<s>
On	O
Android	B-Application
,	O
it	O
can	O
be	O
additionally	O
protected	O
by	O
a	O
passphrase	O
.	O
</s>
<s>
Since	O
2016	O
,	O
Threema	B-Application
GmbH	O
publishes	O
a	O
transparency	O
report	O
where	O
public	O
authority	O
inquiries	O
are	O
disclosed	O
.	O
</s>
<s>
On	O
March	O
9	O
,	O
2017	O
,	O
Threema	B-Application
was	O
listed	O
in	O
the	O
"	O
Register	O
of	O
organizers	O
of	O
information	O
dissemination	O
in	O
the	O
Internet	O
"	O
operated	O
by	O
the	O
Federal	O
Service	O
for	O
Supervision	O
of	O
Communications	O
,	O
Information	O
Technology	O
and	O
Mass	O
Media	O
of	O
the	O
Russian	O
Federation	O
.	O
</s>
<s>
In	O
a	O
response	O
,	O
a	O
Threema	B-Application
spokesperson	O
publicly	O
stated	O
:	O
"	O
We	O
operate	O
under	O
Swiss	O
law	O
and	O
are	O
neither	O
allowed	O
nor	O
willing	O
to	O
provide	O
any	O
information	O
about	O
our	O
users	O
to	O
foreign	O
authorities.	O
"	O
</s>
<s>
On	O
April	O
29	O
,	O
2021	O
,	O
Threema	B-Application
won	O
a	O
significant	O
case	O
at	O
the	O
Federal	O
Supreme	O
Court	O
of	O
Switzerland	B-Protocol
against	O
the	O
Swiss	O
Federal	O
Department	O
of	O
Police	O
and	O
Justice	O
,	O
who	O
wished	O
to	O
classify	O
the	O
company	O
as	O
a	O
telecommunications	O
provider	O
.	O
</s>
<s>
Had	O
they	O
lost	O
the	O
case	O
,	O
Threema	B-Application
would	O
have	O
had	O
a	O
legal	O
requirement	O
to	O
identify	O
users	O
and	O
send	O
information	O
about	O
their	O
users	O
to	O
law	O
enforcement	O
.	O
</s>
<s>
Starting	O
January	O
2022	O
,	O
Swiss	O
Armed	O
Forces	O
suggested	O
that	O
the	O
troops	O
should	O
use	O
Threema	B-Application
instead	O
of	O
WhatsApp	B-Application
,	O
Telegram	B-Application
and	O
Signal	B-Application
,	O
citing	O
Threema	B-Application
being	O
Swiss-based	O
without	O
servers	B-Application
in	O
the	O
United	O
States	O
and	O
thus	O
not	O
subject	O
to	O
the	O
CLOUD	O
Act	O
,	O
also	O
promising	O
that	O
soldiers	O
would	O
be	O
reimbursed	O
for	O
the	O
cost	O
.	O
</s>
<s>
In	O
February	O
2014	O
,	O
German	O
consumer	O
organisation	O
Stiftung	O
Warentest	O
evaluated	O
several	O
data-protection	O
aspects	O
of	O
Threema	B-Application
,	O
WhatsApp	B-Application
,	O
Telegram	B-Application
,	O
BlackBerry	B-Application
Messenger	I-Application
and	O
Line	B-Application
.	O
</s>
<s>
Threema	B-Application
was	O
the	O
only	O
app	O
rated	O
as	O
'	O
non-critical	O
'	O
(	O
)	O
in	O
relation	O
to	O
data	O
and	O
privacy	O
protection	O
,	O
but	O
lost	O
marks	O
due	O
to	O
its	O
closed-source	O
nature	O
,	O
though	O
this	O
has	O
changed	O
for	O
its	O
frontend	O
clients	O
since	O
the	O
end	O
of	O
2020	O
.	O
</s>
<s>
Along	O
with	O
Cryptocat	B-Protocol
and	O
Surespot	B-Protocol
,	O
Threema	B-Application
was	O
ranked	O
first	O
in	O
a	O
study	O
evaluating	O
the	O
security	O
and	O
usability	O
of	O
instant	B-Application
messaging	I-Application
encryption	O
software	O
,	O
conducted	O
by	O
the	O
German	O
PSW	O
Group	O
in	O
June	O
2014	O
.	O
</s>
<s>
,	O
Threema	B-Application
had	O
a	O
score	O
of	O
6	O
out	O
of	O
7	O
points	O
on	O
the	O
–	O
now	O
withdrawn	O
and	O
outdated	O
–	O
Electronic	O
Frontier	O
Foundation	O
's	O
"	O
Secure	O
Messaging	O
Scorecard	O
"	O
.	O
</s>
<s>
it	O
was	O
not	O
open-source	B-Application
,	O
though	O
in	O
late	O
2020	O
its	O
frontend	O
apps	O
were	O
open-sourced	O
,	O
leaving	O
only	O
its	O
server	O
component	O
proprietary	O
)	O
.	O
</s>
