<s>
xx	B-Application
messenger	I-Application
is	O
a	O
cross-platform	B-Operating_System
decentralized	B-Operating_System
encrypted	O
instant	B-Application
messaging	I-Application
service	O
developed	O
by	O
PrivaTegrity	O
Corporation	O
.	O
</s>
<s>
Messages	O
are	O
delivered	O
over	O
a	O
variety	O
of	O
mix	B-Protocol
network	I-Protocol
first	O
described	O
in	O
2016	O
.	O
</s>
<s>
Users	O
can	O
send	O
one-to-one	O
and	O
group	O
messages	O
,	O
which	O
can	O
include	O
voice	O
notes	O
and	O
images	B-Algorithm
.	O
</s>
<s>
xx	B-Application
messenger	I-Application
uses	O
usernames	O
as	O
identifiers	O
which	O
can	O
be	O
optionally	O
attached	O
to	O
standard	O
cellular	O
telephone	O
numbers	O
or	O
email	O
addresses	O
for	O
contact	O
discovery	O
.	O
</s>
<s>
xx	B-Application
messenger	I-Application
's	O
software	O
is	O
free	B-License
and	I-License
open-source	I-License
.	O
</s>
<s>
Its	O
mobile	B-Application
clients	I-Application
are	O
published	O
under	O
the	O
2-clause	O
BSD	O
License	O
,	O
while	O
its	O
server	O
software	O
is	O
published	O
under	O
a	O
modified	O
,	O
patent-protected	O
Business	O
Source	O
License	O
.	O
</s>
<s>
An	O
alpha	O
version	O
of	O
xx	B-Application
messenger	I-Application
was	O
first	O
presented	O
on	O
January	O
6	O
,	O
2016	O
by	O
David	O
Chaum	O
at	O
the	O
Real	O
World	O
Crypto	O
conference	O
with	O
the	O
stated	O
goal	O
of	O
demonstrating	O
a	O
new	O
type	O
of	O
mix	B-Protocol
network	I-Protocol
encryption	O
scheme	O
.	O
</s>
<s>
xx	B-Application
messenger	I-Application
was	O
released	O
to	O
the	O
public	O
as	O
a	O
mobile	B-Application
app	I-Application
on	O
Android	B-Application
and	O
IOS	B-Application
on	O
25	O
January	O
2022	O
.	O
</s>
<s>
xx	B-Application
messenger	I-Application
uses	O
cMix	O
-	O
a	O
network	O
of	O
decentralized	B-Operating_System
servers	O
that	O
are	O
run	O
by	O
independent	O
operators	O
in	O
approximately	O
80	O
countries	O
-	O
for	O
data	O
transmission	O
.	O
</s>
<s>
cMix	O
attempts	O
to	O
address	O
traditional	O
latency	B-Protocol
and	O
scalability	B-Architecture
limitations	O
of	O
mix	B-Protocol
networks	I-Protocol
by	O
performing	O
computationally	O
expensive	O
public-key	B-Application
operations	O
between	O
mix	O
nodes	O
prior	O
to	O
any	O
client	O
data	O
being	O
transmitted	O
over	O
the	O
network	O
.	O
</s>
<s>
Messages	O
sent	O
by	O
users	O
of	O
xx	B-Application
messenger	I-Application
are	O
grouped	O
in	O
batches	O
of	O
1,000	O
and	O
routed	O
through	O
a	O
subset	O
of	O
cMix	O
nodes	O
.	O
</s>
<s>
The	O
cMix	O
protocol	O
uses	O
XChaCha20	O
,	O
BLAKE2b	B-Algorithm
,	O
HMAC-SHA-256	B-Algorithm
,	O
Diffie	B-Protocol
–	I-Protocol
Hellman	I-Protocol
key	I-Protocol
exchange	I-Protocol
,	O
and	O
Supersingular	B-Algorithm
isogeny	I-Algorithm
key	I-Algorithm
exchange	I-Algorithm
as	O
cryptographic	O
primitives	O
.	O
</s>
<s>
This	O
payload	O
is	O
then	O
encrypted	O
once	O
more	O
for	O
transmission	O
over	O
the	O
mixnet	B-Protocol
using	O
multi-party	O
ElGamal	B-Algorithm
encryption	I-Algorithm
.	O
</s>
<s>
The	O
encryption	O
protocols	O
,	O
in	O
addition	O
to	O
the	O
properties	O
provided	O
by	O
the	O
mixnet	B-Protocol
,	O
allow	O
both	O
anonymity	O
preservation	O
and	O
traditional	O
end-to-end	O
security	O
guarantees	O
,	O
as	O
well	O
as	O
preliminary	O
post-quantum	O
security	O
with	O
a	O
traditional	O
fallback	O
mechanism	O
.	O
</s>
