<s>
Mailvelope	B-Operating_System
is	O
a	O
free	B-Application
software	I-Application
for	O
end-to-end	O
encryption	O
of	O
email	O
traffic	O
inside	O
of	O
a	O
web	B-Application
browser	I-Application
(	O
Firefox	B-Application
,	O
Chromium	B-Language
or	O
Edge	B-Application
)	O
that	O
integrates	O
itself	O
into	O
existing	O
webmail	B-Protocol
applications	O
(	O
"	O
email	O
websites	O
"	O
)	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
to	O
encrypt	O
and	O
sign	O
electronic	O
messages	O
,	O
including	O
attached	O
files	O
,	O
without	O
the	O
use	O
of	O
a	O
separate	O
,	O
native	O
email	B-Protocol
client	I-Protocol
(	O
like	O
Thunderbird	O
)	O
using	O
the	O
OpenPGP	O
standard	O
.	O
</s>
<s>
It	O
is	O
published	O
together	O
with	O
its	O
source	O
code	O
under	O
the	O
terms	O
of	O
version	O
3	O
of	O
the	O
GNU	B-Application
Affero	I-Application
General	I-Application
Public	I-Application
License	I-Application
(	O
AGPL	B-Application
)	O
.	O
</s>
<s>
The	O
company	O
Mailvelope	B-Operating_System
GmbH	O
runs	O
the	O
development	O
using	O
a	O
public	O
code	O
repository	O
on	O
GitHub	B-Application
.	O
</s>
<s>
Mailvelope	B-Operating_System
equips	O
webmail	B-Protocol
applications	O
with	O
OpenPGP	O
functionality	O
.	O
</s>
<s>
Support	O
for	O
several	O
popular	O
providers	O
like	O
Gmail	B-Application
,	O
Yahoo	B-Application
,	O
Outlook	B-Protocol
on	I-Protocol
the	I-Protocol
web	I-Protocol
and	O
others	O
are	O
preconfigured	O
.	O
</s>
<s>
The	O
webmail	B-Protocol
software	O
Roundcube	B-Language
senses	O
and	O
supports	O
Mailvelope	B-Operating_System
as	O
of	O
version	O
1.2	O
from	O
May	O
2016	O
,	O
as	O
well	O
as	O
most	O
(	O
self-hosted	O
)	O
webmail	B-Protocol
clients	O
.	O
</s>
<s>
For	O
Chromium/Chrome	O
there	O
's	O
the	O
possibility	O
to	O
install	O
from	O
an	O
authenticated	O
source	O
using	O
the	O
integrated	O
software	O
extension	O
manager	O
"	O
Chrome	B-Application
Web	I-Application
Store	I-Application
"	O
.	O
</s>
<s>
In	O
addition	O
,	O
Mailvelope	B-Operating_System
is	O
also	O
available	O
for	O
Firefox	B-Application
and	O
Microsoft	B-Application
Edge	I-Application
as	O
an	O
add-on	B-Operating_System
.	O
</s>
<s>
Mailvelope	B-Operating_System
works	O
according	O
to	O
the	O
OpenPGP	O
standard	O
,	O
a	O
public-key	B-Application
cryptosystem	I-Application
first	O
standardized	O
in	O
1998	O
and	O
is	O
written	O
in	O
JavaScript	B-Language
.	O
</s>
<s>
For	O
encryption	O
it	O
relies	O
on	O
the	O
functionality	O
of	O
the	O
program	B-Library
library	I-Library
OpenPGP.js	O
,	O
a	O
free	O
JavaScript	B-Language
Implementation	O
of	O
the	O
OpenPGP	O
standard	O
.	O
</s>
<s>
The	O
integration	O
of	O
Mailvelope	B-Operating_System
via	O
an	O
API	O
,	O
developed	O
in	O
collaboration	O
with	O
United	O
Internet	O
,	O
allows	O
deeper	O
integration	O
between	O
the	O
webmail	B-Protocol
service	O
and	O
Mailvelope	B-Operating_System
components	O
.	O
</s>
<s>
Thus	O
,	O
the	O
setup	O
and	O
generation	O
of	O
a	O
key	B-Application
pair	I-Application
can	O
be	O
done	O
directly	O
in	O
the	O
webmailer	O
using	O
a	O
wizard	O
.	O
</s>
<s>
Mailvelope	B-Operating_System
manages	O
all	O
OpenPGP	O
keys	O
locally	O
in	O
the	O
browser	B-Application
.	O
</s>
<s>
Since	O
version	O
3.0	O
,	O
a	O
local	O
GnuPG	O
installation	O
can	O
be	O
included	O
in	O
Mailvelope	B-Operating_System
's	O
key	O
management	O
,	O
allowing	O
users	O
to	O
use	O
native	O
applications	O
if	O
desired	O
.	O
</s>
<s>
Thomas	O
Oberndörfer	O
started	O
developing	O
Mailvelope	B-Operating_System
in	O
spring	O
2012	O
with	O
the	O
first	O
public	O
version	O
0.4.0.1	O
released	O
on	O
August	O
24	O
.	O
</s>
<s>
Moreover	O
,	O
the	O
webmail	B-Protocol
services	O
that	O
were	O
particularly	O
popular	O
with	O
private	O
individuals	O
did	O
not	O
offer	O
any	O
end-to-end	O
encryption	O
functions	O
.	O
</s>
<s>
This	O
led	O
to	O
various	O
mentions	O
of	O
Mailvelope	B-Operating_System
in	O
the	O
press	O
as	O
a	O
possible	O
solution	O
to	O
this	O
problem	O
.	O
</s>
<s>
In	O
February	O
2014	O
,	O
the	O
same	O
group	O
analysed	O
the	O
library	O
OpenPGP.js	O
which	O
Mailvelope	B-Operating_System
is	O
based	O
on	O
.	O
</s>
<s>
In	O
May	O
2014	O
,	O
iSEC	O
Partners	O
published	O
an	O
analysis	O
of	O
the	O
Firefox	B-Application
extension	O
.	O
</s>
<s>
In	O
April	O
2015	O
,	O
De-Mail	O
providers	O
equipped	O
their	O
services	O
with	O
a	O
default	O
disabled	O
option	O
for	O
end-to-end	O
encryption	O
based	O
on	O
Mailvelope	B-Operating_System
,	O
but	O
it	O
could	O
only	O
be	O
used	O
in	O
combination	O
with	O
Mobile	O
TAN	O
or	O
the	O
German	O
electronic	O
identity	O
card	O
.	O
</s>
<s>
In	O
August	O
2015	O
,	O
the	O
email	O
services	O
of	O
Web.de	O
and	O
GMX	B-General_Concept
introduced	O
support	O
for	O
OpenPGP	O
encryption	O
and	O
integrated	O
Mailvelope	B-Operating_System
into	O
their	O
webmail	B-Protocol
applications	O
for	O
that	O
.	O
</s>
<s>
A	O
2015	O
study	O
examined	O
the	O
usability	O
of	O
Mailvelope	B-Operating_System
as	O
an	O
example	O
of	O
a	O
modern	O
OpenPGP	O
client	O
and	O
deemed	O
it	O
unsuitable	O
for	O
the	O
masses	O
.	O
</s>
<s>
The	O
Mailvelope-based	O
OpenPGP	O
system	O
of	O
United	O
Internet	O
integrates	O
such	O
functionality	O
and	O
its	O
usability	O
earned	O
some	O
positive	O
mentions	O
in	O
the	O
press	O
,	O
particularly	O
the	O
offered	O
key	O
synchronization	O
feature	O
.	O
</s>
<s>
Mailvelope	B-Operating_System
was	O
enhanced	O
in	O
2018/19	O
as	O
part	O
of	O
a	O
BSI	O
initiative	O
.	O
</s>
<s>
All	O
security	O
vulnerabilities	O
in	O
the	O
Mailvelope	B-Operating_System
source	O
code	O
,	O
as	O
well	O
as	O
in	O
the	O
OpenPGP.js	O
program	B-Library
library	I-Library
used	O
,	O
brought	O
to	O
light	O
by	O
a	O
security	O
audit	O
conducted	O
by	O
SEC	O
Consult	O
were	O
closed	O
.	O
</s>
<s>
According	O
to	O
the	O
BSI	O
,	O
one	O
goal	O
of	O
the	O
project	O
was	O
also	O
to	O
enable	O
website	O
operators	O
to	O
offer	O
contact	O
forms	O
in	O
the	O
future	O
to	O
securely	O
encrypt	O
messages	O
from	O
the	O
user	O
's	O
browser	B-Application
to	O
the	O
recipient	O
.	O
</s>
