<s>
Pretty	B-Application
Good	I-Application
Privacy	I-Application
(	O
PGP	O
)	O
is	O
an	O
encryption	O
program	O
that	O
provides	O
cryptographic	O
privacy	O
and	O
authentication	O
for	O
data	O
communication	O
.	O
</s>
<s>
PGP	O
and	O
similar	O
software	O
follow	O
the	O
OpenPGP	O
,	O
an	O
open	O
standard	O
of	O
PGP	B-Application
encryption	I-Application
software	O
,	O
standard	O
(	O
RFC	O
4880	O
)	O
for	O
encrypting	O
and	O
decrypting	O
data	O
.	O
</s>
<s>
PGPencryption	O
uses	O
a	O
serial	O
combination	O
of	O
hashing	B-Algorithm
,	O
data	B-General_Concept
compression	I-General_Concept
,	O
symmetric-key	B-Algorithm
cryptography	I-Algorithm
,	O
and	O
finally	O
public-key	B-Application
cryptography	I-Application
;	O
each	O
step	O
uses	O
one	O
of	O
several	O
supported	O
algorithms	O
.	O
</s>
<s>
Each	O
public	B-Application
key	I-Application
is	O
bound	O
to	O
a	O
username	O
or	O
an	O
e-mail	O
address	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
this	O
system	O
was	O
generally	O
known	O
as	O
a	O
web	O
of	O
trust	O
to	O
contrast	O
with	O
the	O
X.509	O
system	O
,	O
which	O
uses	O
a	O
hierarchical	O
approach	O
based	O
on	O
certificate	B-Architecture
authority	I-Architecture
and	O
which	O
was	O
added	O
to	O
PGP	O
implementations	O
later	O
.	O
</s>
<s>
Current	O
versions	O
of	O
PGP	B-Application
encryption	I-Application
include	O
options	O
through	O
an	O
automated	O
key	O
management	O
server	O
.	O
</s>
<s>
A	O
public	B-Algorithm
key	I-Algorithm
fingerprint	I-Algorithm
is	O
a	O
shorter	O
version	O
of	O
a	O
public	B-Application
key	I-Application
.	O
</s>
<s>
From	O
a	O
fingerprint	B-Algorithm
,	O
someone	O
can	O
validate	O
the	O
correct	O
corresponding	O
public	B-Application
key	I-Application
.	O
</s>
<s>
A	O
fingerprint	B-Algorithm
like	O
C3A6	O
5E46	O
7B54	O
77DF	O
3C4C	O
9790	O
4D22	O
B3CA	O
5B32	O
FF66	O
can	O
be	O
printed	O
on	O
a	O
business	O
card	O
.	O
</s>
<s>
As	O
PGP	O
evolves	O
,	O
versions	O
that	O
support	O
newer	O
features	O
and	O
algorithms	O
can	O
create	O
encrypted	O
messages	O
that	O
older	O
PGP	O
systems	O
cannot	O
decrypt	O
,	O
even	O
with	O
a	O
valid	O
private	B-Application
key	I-Application
.	O
</s>
<s>
For	O
this	O
,	O
PGP	O
uses	O
a	O
hybrid	O
cryptosystem	B-General_Concept
by	O
combining	O
symmetric-key	B-Algorithm
encryption	I-Algorithm
and	O
public-key	B-Application
encryption	I-Application
.	O
</s>
<s>
The	O
message	O
is	O
encrypted	O
using	O
a	O
symmetric	B-Algorithm
encryption	I-Algorithm
algorithm	O
,	O
which	O
requires	O
a	O
symmetric	B-Algorithm
key	I-Algorithm
generated	O
by	O
the	O
sender	O
.	O
</s>
<s>
The	O
symmetric	B-Algorithm
key	I-Algorithm
is	O
used	O
only	O
once	O
and	O
is	O
also	O
called	O
a	O
session	O
key	O
.	O
</s>
<s>
The	O
session	O
key	O
must	O
be	O
sent	O
to	O
the	O
receiver	O
so	O
they	O
know	O
how	O
to	O
decrypt	O
the	O
message	O
,	O
but	O
to	O
protect	O
it	O
during	O
transmission	O
it	O
is	O
encrypted	O
with	O
the	O
receiver	O
's	O
public	B-Application
key	I-Application
.	O
</s>
<s>
Only	O
the	O
private	B-Application
key	I-Application
belonging	O
to	O
the	O
receiver	O
can	O
decrypt	O
the	O
session	O
key	O
,	O
and	O
use	O
it	O
to	O
symmetrically	O
decrypt	O
the	O
message	O
.	O
</s>
<s>
The	O
sender	O
uses	O
PGP	O
to	O
create	O
a	O
digital	O
signature	O
for	O
the	O
message	O
with	O
either	O
the	O
RSA	B-Architecture
or	O
DSA	O
algorithms	O
.	O
</s>
<s>
To	O
do	O
so	O
,	O
PGP	O
computes	O
a	O
hash	B-Algorithm
(	O
also	O
called	O
a	O
message	B-Algorithm
digest	I-Algorithm
)	O
from	O
the	O
plaintext	O
and	O
then	O
creates	O
the	O
digital	O
signature	O
from	O
that	O
hash	B-Algorithm
using	O
the	O
sender	O
's	O
private	B-Application
key	I-Application
.	O
</s>
<s>
Both	O
when	O
encrypting	O
messages	O
and	O
when	O
verifying	O
signatures	O
,	O
it	O
is	O
critical	O
that	O
the	O
public	B-Application
key	I-Application
used	O
to	O
send	O
messages	O
to	O
someone	O
or	O
some	O
entity	O
actually	O
does	O
'	O
belong	O
 '	O
to	O
the	O
intended	O
recipient	O
.	O
</s>
<s>
Simply	O
downloading	O
a	O
public	B-Application
key	I-Application
from	O
somewhere	O
is	O
not	O
a	O
reliable	O
assurance	O
of	O
that	O
association	O
;	O
deliberate	O
(	O
or	O
accidental	O
)	O
impersonation	O
is	O
possible	O
.	O
</s>
<s>
From	O
its	O
first	O
version	O
,	O
PGP	O
has	O
always	O
included	O
provisions	O
for	O
distributing	O
user	O
's	O
public	B-Application
keys	I-Application
in	O
an	O
'	O
identity	O
certification	O
 '	O
,	O
which	O
is	O
also	O
constructed	O
cryptographically	O
so	O
that	O
any	O
tampering	O
(	O
or	O
accidental	O
garble	O
)	O
is	O
readily	O
detectable	O
.	O
</s>
<s>
Users	O
must	O
also	O
ensure	O
by	O
some	O
means	O
that	O
the	O
public	B-Application
key	I-Application
in	O
a	O
certificate	O
actually	O
does	O
belong	O
to	O
the	O
person	O
or	O
entity	O
claiming	O
it	O
.	O
</s>
<s>
A	O
given	O
public	B-Application
key	I-Application
(	O
or	O
more	O
specifically	O
,	O
information	O
binding	O
a	O
user	O
name	O
to	O
a	O
key	O
)	O
may	O
be	O
digitally	O
signed	O
by	O
a	O
third-party	O
user	O
to	O
attest	O
to	O
the	O
association	O
between	O
someone	O
(	O
actually	O
a	O
user	O
name	O
)	O
and	O
the	O
key	O
.	O
</s>
<s>
The	O
web	O
of	O
trust	O
mechanism	O
has	O
advantages	O
over	O
a	O
centrally	O
managed	O
public	B-Architecture
key	I-Architecture
infrastructure	I-Architecture
scheme	O
such	O
as	O
that	O
used	O
by	O
S/MIME	B-Protocol
but	O
has	O
not	O
been	O
universally	O
used	O
.	O
</s>
<s>
In	O
the	O
(	O
more	O
recent	O
)	O
OpenPGP	O
specification	O
,	O
trust	O
signatures	O
can	O
be	O
used	O
to	O
support	O
creation	O
of	O
certificate	B-Architecture
authorities	I-Architecture
.	O
</s>
<s>
A	O
level	O
1	O
signature	O
is	O
similar	O
to	O
the	O
trust	O
one	O
has	O
in	O
a	O
certificate	B-Architecture
authority	I-Architecture
because	O
a	O
key	O
signed	O
to	O
level	O
1	O
is	O
able	O
to	O
issue	O
an	O
unlimited	O
number	O
of	O
level	O
0	O
signatures	O
.	O
</s>
<s>
A	O
level	O
2	O
signature	O
is	O
highly	O
analogous	O
to	O
the	O
trust	O
assumption	O
users	O
must	O
rely	O
on	O
whenever	O
they	O
use	O
the	O
default	O
certificate	B-Architecture
authority	I-Architecture
list	O
(	O
like	O
those	O
included	O
in	O
web	O
browsers	O
)	O
;	O
it	O
allows	O
the	O
owner	O
of	O
the	O
key	O
to	O
make	O
other	O
keys	O
certificate	B-Architecture
authorities	I-Architecture
.	O
</s>
<s>
PGP	O
versions	O
have	O
always	O
included	O
a	O
way	O
to	O
cancel	O
( 	O
 '	O
revoke	O
 '	O
)	O
public	B-Application
key	I-Application
certificates	O
.	O
</s>
<s>
A	O
lost	O
or	O
compromised	O
private	B-Application
key	I-Application
will	O
require	O
this	O
if	O
communication	O
security	O
is	O
to	O
be	O
retained	O
by	O
that	O
user	O
.	O
</s>
<s>
This	O
is	O
,	O
more	O
or	O
less	O
,	O
equivalent	O
to	O
the	O
certificate	B-Protocol
revocation	I-Protocol
lists	I-Protocol
of	O
centralised	O
PKI	O
schemes	O
.	O
</s>
<s>
The	O
problem	O
of	O
correctly	O
identifying	O
a	O
public	B-Application
key	I-Application
as	O
belonging	O
to	O
a	O
particular	O
user	O
is	O
not	O
unique	O
to	O
PGP	O
.	O
</s>
<s>
All	O
public	O
key/private	O
key	O
cryptosystems	B-General_Concept
have	O
the	O
same	O
problem	O
,	O
even	O
if	O
in	O
slightly	O
different	O
guises	O
,	O
and	O
no	O
fully	O
satisfactory	O
solution	O
is	O
known	O
.	O
</s>
<s>
PGP	O
's	O
original	O
scheme	O
at	O
least	O
leaves	O
the	O
decision	O
as	O
to	O
whether	O
or	O
not	O
to	O
use	O
its	O
endorsement/vetting	O
system	O
to	O
the	O
user	O
,	O
while	O
most	O
other	O
PKI	O
schemes	O
do	O
not	O
,	O
requiring	O
instead	O
that	O
every	O
certificate	O
attested	O
to	O
by	O
a	O
central	O
certificate	B-Architecture
authority	I-Architecture
be	O
accepted	O
as	O
correct	O
.	O
</s>
<s>
To	O
the	O
best	O
of	O
publicly	O
available	O
information	O
,	O
there	O
is	O
no	O
known	O
method	O
which	O
will	O
allow	O
a	O
person	O
or	O
group	O
to	O
break	O
PGP	B-Application
encryption	I-Application
by	O
cryptographic	O
,	O
or	O
computational	O
means	O
.	O
</s>
<s>
In	O
addition	O
to	O
protecting	O
data	B-General_Concept
in	I-General_Concept
transit	I-General_Concept
over	O
a	O
network	O
,	O
PGP	B-Application
encryption	I-Application
can	O
also	O
be	O
used	O
to	O
protect	O
data	O
in	O
long-term	O
data	O
storage	O
such	O
as	O
disk	O
files	O
.	O
</s>
<s>
The	O
cryptographic	O
security	O
of	O
PGP	B-Application
encryption	I-Application
depends	O
on	O
the	O
assumption	O
that	O
the	O
algorithms	O
used	O
are	O
unbreakable	O
by	O
direct	O
cryptanalysis	O
with	O
current	O
equipment	O
and	O
techniques	O
.	O
</s>
<s>
In	O
the	O
original	O
version	O
,	O
the	O
RSA	B-Architecture
algorithm	I-Architecture
was	O
used	O
to	O
encrypt	O
session	O
keys	O
.	O
</s>
<s>
RSA	B-Architecture
's	O
security	O
depends	O
upon	O
the	O
one-way	O
function	O
nature	O
of	O
mathematical	O
integer	O
factoring	O
.	O
</s>
<s>
Similarly	O
,	O
the	O
symmetric	B-Algorithm
key	I-Algorithm
algorithm	I-Algorithm
used	O
in	O
PGP	O
version	O
2	O
was	O
IDEA	B-Algorithm
,	O
which	O
might	O
at	O
some	O
point	O
in	O
the	O
future	O
be	O
found	O
to	O
have	O
previously	O
undetected	O
cryptanalytic	O
flaws	O
.	O
</s>
<s>
Specific	O
instances	O
of	O
current	O
PGP	O
or	O
IDEA	B-Algorithm
insecurities	O
(	O
if	O
they	O
exist	O
)	O
are	O
not	O
publicly	O
known	O
.	O
</s>
<s>
installing	O
some	O
form	O
of	O
trojan	O
horse	O
or	O
keystroke	O
logging	O
software/hardware	O
on	O
the	O
target	O
computer	O
to	O
capture	O
encrypted	O
keyrings	B-General_Concept
and	O
their	O
passwords	O
)	O
.	O
</s>
<s>
In	O
2003	O
,	O
an	O
incident	O
involving	O
seized	O
Psion	B-Application
PDAs	B-Application
belonging	O
to	O
members	O
of	O
the	O
Red	O
Brigade	O
indicated	O
that	O
neither	O
the	O
Italian	O
police	O
nor	O
the	O
FBI	O
were	O
able	O
to	O
decrypt	O
PGP-encrypted	O
files	O
stored	O
on	O
them	O
.	O
</s>
<s>
A	O
second	O
incident	O
in	O
December	O
2006	O
,	O
(	O
see	O
In	O
re	O
Boucher	O
)	O
,	O
involving	O
US	O
customs	O
agents	O
who	O
seized	O
a	O
laptop	B-Device
PC	I-Device
that	O
allegedly	O
contained	O
child	O
pornography	O
,	O
indicates	O
that	O
US	O
government	O
agencies	O
find	O
it	O
"	O
nearly	O
impossible	O
"	O
to	O
access	O
PGP-encrypted	O
files	O
.	O
</s>
<s>
PGP	O
as	O
a	O
cryptosystem	B-General_Concept
has	O
been	O
criticized	O
for	O
complexity	O
of	O
the	O
standard	O
,	O
implementation	O
and	O
very	O
low	O
usability	O
of	O
the	O
user	O
interface	O
including	O
by	O
recognized	O
figures	O
in	O
cryptography	O
research	O
.	O
</s>
<s>
It	O
uses	O
an	O
ineffective	O
serialization	O
format	O
for	O
storage	O
of	O
both	O
keys	O
and	O
encrypted	O
data	O
,	O
which	O
resulted	O
in	O
signature-spamming	O
attacks	O
on	O
public	B-Application
keys	I-Application
of	O
prominent	O
developers	O
of	O
GNU	B-Application
Privacy	I-Application
Guard	I-Application
.	O
</s>
<s>
Backwards	O
compatibility	O
of	O
the	O
OpenPGP	O
standard	O
results	O
in	O
usage	O
of	O
relatively	O
weak	O
default	O
choices	O
of	O
cryptographic	O
primitives	O
(	O
CAST5	B-Algorithm
cipher	O
,	O
CFB	O
mode	O
,	O
S2K	O
password	O
hashing	B-Algorithm
)	O
.	O
</s>
<s>
Phil	O
Zimmermann	O
created	O
the	O
first	O
version	O
of	O
PGP	B-Application
encryption	I-Application
in	O
1991	O
.	O
</s>
<s>
The	O
name	O
,	O
"	O
Pretty	B-Application
Good	I-Application
Privacy	I-Application
"	O
was	O
inspired	O
by	O
the	O
name	O
of	O
a	O
grocery	O
store	O
,	O
"	O
Ralph	O
's	O
Pretty	O
Good	O
Grocery	O
"	O
,	O
featured	O
in	O
radio	O
host	O
Garrison	O
Keillor	O
's	O
fictional	O
town	O
,	O
Lake	O
Wobegon	O
.	O
</s>
<s>
This	O
first	O
version	O
included	O
a	O
symmetric-key	B-Algorithm
algorithm	I-Algorithm
that	O
Zimmermann	O
had	O
designed	O
himself	O
,	O
named	O
BassOmatic	B-Algorithm
after	O
a	O
Saturday	O
Night	O
Live	O
sketch	O
.	O
</s>
<s>
Zimmermann	O
had	O
been	O
a	O
long-time	O
anti-nuclear	O
activist	O
,	O
and	O
created	O
PGP	B-Application
encryption	I-Application
so	O
that	O
similarly	O
inclined	O
people	O
might	O
securely	O
use	O
BBSs	O
and	O
securely	O
store	O
messages	O
and	O
files	O
.	O
</s>
<s>
No	O
license	O
fee	O
was	O
required	O
for	O
its	O
non-commercial	O
use	O
,	O
and	O
the	O
complete	O
source	O
code	O
was	O
included	O
with	O
all	O
copies	O
.	O
</s>
<s>
Users	O
and	O
supporters	O
included	O
dissidents	O
in	O
totalitarian	O
countries	O
(	O
some	O
affecting	O
letters	O
to	O
Zimmermann	O
have	O
been	O
published	O
,	O
some	O
of	O
which	O
have	O
been	O
included	O
in	O
testimony	O
before	O
the	O
US	O
Congress	O
)	O
,	O
civil	O
libertarians	O
in	O
other	O
parts	O
of	O
the	O
world	O
(	O
see	O
Zimmermann	O
's	O
published	O
testimony	O
in	O
various	O
hearings	O
)	O
,	O
and	O
the	O
'	O
free	O
communications	O
 '	O
activists	O
who	O
called	O
themselves	O
cypherpunks	O
(	O
who	O
provided	O
both	O
publicity	O
and	O
distribution	O
)	O
;	O
decades	O
later	O
,	O
CryptoParty	B-Application
activists	O
did	O
much	O
the	O
same	O
via	O
Twitter	B-Application
.	O
</s>
<s>
Shortly	O
after	O
its	O
release	O
,	O
PGP	B-Application
encryption	I-Application
found	O
its	O
way	O
outside	O
the	O
United	O
States	O
,	O
and	O
in	O
February	O
1993	O
Zimmermann	O
became	O
the	O
formal	O
target	O
of	O
a	O
criminal	O
investigation	O
by	O
the	O
US	O
Government	O
for	O
"	O
munitions	O
export	O
without	O
a	O
license	O
"	O
.	O
</s>
<s>
At	O
the	O
time	O
,	O
cryptosystems	B-General_Concept
using	O
keys	O
larger	O
than	O
40	O
bits	O
were	O
considered	O
munitions	O
within	O
the	O
definition	O
of	O
the	O
US	O
export	O
regulations	O
;	O
PGP	O
has	O
never	O
used	O
keys	O
smaller	O
than	O
128	O
bits	O
,	O
so	O
it	O
qualified	O
at	O
that	O
time	O
.	O
</s>
<s>
Anybody	O
wishing	O
to	O
build	O
their	O
own	O
copy	O
of	O
PGP	O
could	O
cut	O
off	O
the	O
covers	O
,	O
separate	O
the	O
pages	O
,	O
and	O
scan	O
them	O
using	O
an	O
OCR	B-Application
program	O
(	O
or	O
conceivably	O
enter	O
it	O
as	O
a	O
type-in	O
program	O
if	O
OCR	B-Application
software	O
was	O
not	O
available	O
)	O
,	O
creating	O
a	O
set	O
of	O
source	O
code	O
text	O
files	O
.	O
</s>
<s>
One	O
could	O
then	O
build	O
the	O
application	O
using	O
the	O
freely	O
available	O
GNU	B-Application
Compiler	I-Application
Collection	I-Application
.	O
</s>
<s>
PGP	B-Application
encryption	I-Application
no	O
longer	O
meets	O
the	O
definition	O
of	O
a	O
non-exportable	O
weapon	O
,	O
and	O
can	O
be	O
exported	O
internationally	O
except	O
to	O
seven	O
specific	O
countries	O
and	O
a	O
list	O
of	O
named	O
groups	O
and	O
individuals	O
(	O
with	O
whom	O
substantially	O
all	O
US	O
trade	O
is	O
prohibited	O
under	O
various	O
US	O
export	O
controls	O
)	O
.	O
</s>
<s>
During	O
this	O
turmoil	O
,	O
Zimmermann	O
's	O
team	O
worked	O
on	O
a	O
new	O
version	O
of	O
PGP	B-Application
encryption	I-Application
called	O
PGP	O
3	O
.	O
</s>
<s>
PGP	O
3	O
introduced	O
the	O
use	O
of	O
the	O
CAST-128	B-Algorithm
(	O
a.k.a.	O
</s>
<s>
CAST5	B-Algorithm
)	O
symmetric	B-Algorithm
key	I-Algorithm
algorithm	I-Algorithm
,	O
and	O
the	O
DSA	O
and	O
ElGamal	B-Algorithm
asymmetric	B-Application
key	I-Application
algorithms	I-Application
,	O
all	O
of	O
which	O
were	O
unencumbered	O
by	O
patents	O
.	O
</s>
<s>
After	O
the	O
Federal	O
criminal	O
investigation	O
ended	O
in	O
1996	O
,	O
Zimmermann	O
and	O
his	O
team	O
started	O
a	O
company	O
to	O
produce	O
new	O
versions	O
of	O
PGP	B-Application
encryption	I-Application
.	O
</s>
<s>
They	O
merged	O
with	O
Viacrypt	O
(	O
to	O
whom	O
Zimmermann	O
had	O
sold	O
commercial	B-Application
rights	O
and	O
who	O
had	O
licensed	O
RSA	B-Architecture
directly	O
from	O
RSADSI	O
)	O
,	O
which	O
then	O
changed	O
its	O
name	O
to	O
PGP	O
Incorporated	O
.	O
</s>
<s>
The	O
newly	O
combined	O
Viacrypt/PGP	O
team	O
started	O
work	O
on	O
new	O
versions	O
of	O
PGP	B-Application
encryption	I-Application
based	O
on	O
the	O
PGP	O
3	O
system	O
.	O
</s>
<s>
Unlike	O
PGP	O
2	O
,	O
which	O
was	O
an	O
exclusively	O
command	B-Application
line	I-Application
program	O
,	O
PGP	O
3	O
was	O
designed	O
from	O
the	O
start	O
as	O
a	O
software	B-Library
library	I-Library
allowing	O
users	O
to	O
work	O
from	O
a	O
command	B-Application
line	I-Application
or	O
inside	O
a	O
GUI	B-Application
environment	O
.	O
</s>
<s>
Under	O
NAI	O
,	O
the	O
PGP	O
team	O
added	O
disk	O
encryption	O
,	O
desktop	O
firewalls	O
,	O
intrusion	O
detection	O
,	O
and	O
IPsec	B-Protocol
VPNs	B-Application
to	O
the	O
PGP	O
family	O
.	O
</s>
<s>
He	O
served	O
as	O
Chief	O
Cryptographer	O
for	O
Hush	B-Application
Communications	I-Application
,	O
who	O
provide	O
an	O
OpenPGP-based	O
e-mail	O
service	O
,	O
Hushmail	B-Application
.	O
</s>
<s>
In	O
October	O
2001	O
,	O
NAI	O
announced	O
that	O
its	O
PGP	O
assets	O
were	O
for	O
sale	O
and	O
that	O
it	O
was	O
suspending	O
further	O
development	O
of	O
PGP	B-Application
encryption	I-Application
.	O
</s>
<s>
The	O
only	O
remaining	O
asset	O
kept	O
was	O
the	O
PGP	O
E-Business	O
Server	O
(	O
the	O
original	O
PGP	O
Commandline	B-Application
version	O
)	O
.	O
</s>
<s>
In	O
February	O
2002	O
,	O
NAI	O
canceled	O
all	O
support	O
for	O
PGP	O
products	O
,	O
with	O
the	O
exception	O
of	O
the	O
renamed	O
commandline	B-Application
product	O
.	O
</s>
<s>
In	O
August	O
2002	O
,	O
several	O
ex-PGP	O
team	O
members	O
formed	O
a	O
new	O
company	O
,	O
PGP	O
Corporation	O
,	O
and	O
bought	O
the	O
PGP	O
assets	O
(	O
except	O
for	O
the	O
command	B-Application
line	I-Application
version	O
)	O
from	O
NAI	O
.	O
</s>
<s>
In	O
mid-2004	O
,	O
PGP	O
Corporation	O
shipped	O
its	O
own	O
command	B-Application
line	I-Application
version	O
called	O
PGP	O
Command	B-Application
Line	I-Application
,	O
which	O
integrated	O
with	O
the	O
other	O
PGP	B-Application
Encryption	I-Application
Platform	O
applications	O
.	O
</s>
<s>
In	O
2010	O
,	O
PGP	O
Corporation	O
acquired	O
Hamburg-based	O
certificate	B-Architecture
authority	I-Architecture
TC	O
TrustCenter	O
and	O
its	O
parent	O
company	O
,	O
ChosenSecurity	O
,	O
to	O
form	O
its	O
PGP	O
TrustCenter	O
division	O
.	O
</s>
<s>
The	O
source	O
code	O
of	O
PGP	B-Application
Desktop	I-Application
10	O
is	O
available	O
for	O
peer	O
review	O
.	O
</s>
<s>
For	O
the	O
enterprise	O
,	O
Townsend	O
Security	O
currently	O
offers	O
a	O
commercial	B-Application
version	O
of	O
PGP	O
for	O
the	O
IBM	B-Application
i	I-Application
and	O
IBM	B-Application
z	I-Application
mainframe	O
platforms	O
.	O
</s>
<s>
Townsend	O
Security	O
partnered	O
with	O
Network	O
Associates	O
in	O
2000	O
to	O
create	O
a	O
compatible	O
version	O
of	O
PGP	O
for	O
the	O
IBM	B-Application
i	I-Application
platform	O
.	O
</s>
<s>
Townsend	O
Security	O
again	O
ported	O
PGP	O
in	O
2008	O
,	O
this	O
time	O
to	O
the	O
IBM	B-Application
z	I-Application
mainframe	O
.	O
</s>
<s>
This	O
version	O
of	O
PGP	O
relies	O
on	O
a	O
free	O
z/OS	B-Application
encryption	O
facility	O
,	O
which	O
utilizes	O
hardware	O
acceleration	O
.	O
</s>
<s>
Software	O
Diversified	O
Services	O
also	O
offers	O
a	O
commercial	B-Application
version	O
of	O
PGP	O
(	O
SDS	O
E-Business	O
Server	O
)	O
for	O
the	O
IBM	B-Application
z	I-Application
mainframe	O
.	O
</s>
<s>
The	O
chosen	O
mitigation	O
for	O
this	O
vulnerability	O
in	O
PGP	B-Application
Desktop	I-Application
is	O
to	O
mandate	O
the	O
use	O
SEIP	O
protected	O
packets	O
in	O
the	O
ciphertext	O
,	O
which	O
can	O
lead	O
to	O
old	O
emails	O
or	O
other	O
encrypted	O
objects	O
to	O
be	O
no	O
longer	O
decryptable	O
after	O
upgrading	O
to	O
the	O
software	O
version	O
that	O
has	O
the	O
mitigation	O
.	O
</s>
<s>
This	O
section	O
describes	O
commercial	B-Application
programs	O
available	O
from	O
PGP	O
Corporation	O
.	O
</s>
<s>
PGP	B-Application
encryption	I-Application
applications	O
include	O
e-mails	O
and	O
attachments	O
,	O
digital	O
signatures	O
,	O
full	O
disk	O
encryption	O
,	O
file	O
and	O
folder	O
security	O
,	O
protection	O
for	O
IM	O
sessions	O
,	O
batch	O
file	O
transfer	O
encryption	O
,	O
and	O
protection	O
for	O
files	O
and	O
folders	O
stored	O
on	O
network	O
servers	O
and	O
,	O
more	O
recently	O
,	O
encrypted	O
or	O
signed	O
HTTP	O
request/responses	O
by	O
means	O
of	O
a	O
client-side	O
(	O
Enigform	O
)	O
and	O
a	O
server-side	O
(	O
mod	B-Application
openpgp	I-Application
)	O
module	O
.	O
</s>
<s>
The	O
PGP	B-Application
Desktop	I-Application
9.x	O
family	O
includes	O
PGP	B-Application
Desktop	I-Application
Email	O
,	O
PGP	O
Whole	O
Disk	O
Encryption	O
,	O
and	O
PGP	O
NetShare	O
.	O
</s>
<s>
Depending	O
on	O
the	O
application	O
,	O
the	O
products	O
feature	O
desktop	O
e-mail	O
,	O
digital	O
signatures	O
,	O
IM	O
security	O
,	O
whole	O
disk	O
encryption	O
,	O
file	O
,	O
and	O
folder	O
security	O
,	O
encrypted	O
self-extracting	B-General_Concept
archives	I-General_Concept
,	O
and	O
secure	O
shredding	O
of	O
deleted	O
files	O
.	O
</s>
<s>
It	O
is	O
used	O
for	O
automated	O
e-mail	B-Protocol
encryption	I-Protocol
in	O
the	O
gateway	O
and	O
manages	O
PGP	B-Application
Desktop	I-Application
9.x	O
clients	O
.	O
</s>
<s>
With	O
PGP	B-Application
Desktop	I-Application
9.x	O
managed	O
by	O
PGP	O
Universal	O
Server	O
2.x	O
,	O
first	O
released	O
in	O
2005	O
,	O
all	O
PGP	B-Application
encryption	I-Application
applications	O
are	O
based	O
on	O
a	O
new	O
proxy-based	O
architecture	O
.	O
</s>
<s>
The	O
PGP	O
Universal	O
server	O
automates	O
the	O
creation	O
,	O
management	O
,	O
and	O
expiration	O
of	O
keys	O
,	O
sharing	O
these	O
keys	O
among	O
all	O
PGP	B-Application
encryption	I-Application
applications	O
.	O
</s>
<s>
PGP	B-Application
Desktop	I-Application
is	O
now	O
known	O
as	O
Symantec	O
Encryption	O
Desktop	O
(	O
SED	O
)	O
,	O
and	O
the	O
PGP	O
Universal	O
Server	O
is	O
now	O
known	O
as	O
Symantec	O
Encryption	O
Management	O
Server	O
(	O
SEMS	O
)	O
.	O
</s>
<s>
The	O
current	O
shipping	O
versions	O
are	O
Symantec	O
Encryption	O
Desktop	O
10.3.0	O
(	O
Windows	O
and	O
macOS	B-Application
platforms	O
)	O
and	O
Symantec	O
Encryption	O
Server	O
3.3.2	O
.	O
</s>
<s>
Also	O
available	O
are	O
PGP	O
Command-Line	B-Application
,	O
which	O
enables	O
command	O
line-based	O
encryption	O
and	O
signing	O
of	O
information	O
for	O
storage	O
,	O
transfer	O
,	O
and	O
backup	O
,	O
as	O
well	O
as	O
the	O
PGP	O
Support	O
Package	O
for	O
BlackBerry	O
which	O
enables	O
RIM	O
BlackBerry	O
devices	O
to	O
enjoy	O
sender-to-recipient	O
messaging	O
encryption	O
.	O
</s>
<s>
New	O
versions	O
of	O
PGP	O
applications	O
use	O
both	O
OpenPGP	O
and	O
the	O
S/MIME	B-Protocol
,	O
allowing	O
communications	O
with	O
any	O
user	O
of	O
a	O
NIST	O
specified	O
standard	O
.	O
</s>
<s>
RSADSI	O
was	O
challenging	O
the	O
continuation	O
of	O
the	O
Viacrypt	O
RSA	B-Architecture
license	O
to	O
the	O
newly	O
merged	O
firm	O
.	O
</s>
<s>
Because	O
of	O
PGP	B-Application
encryption	I-Application
's	O
importance	O
worldwide	O
,	O
many	O
wanted	O
to	O
write	O
their	O
own	O
software	O
that	O
would	O
interoperate	O
with	O
PGP	O
5	O
.	O
</s>
<s>
Zimmermann	O
became	O
convinced	O
that	O
an	O
open	O
standard	O
for	O
PGP	B-Application
encryption	I-Application
was	O
critical	O
for	O
them	O
and	O
for	O
the	O
cryptographic	O
community	O
as	O
a	O
whole	O
.	O
</s>
<s>
RFC	O
4880	O
specifies	O
a	O
suite	O
of	O
required	O
algorithms	O
consisting	O
of	O
ElGamal	B-Algorithm
encryption	I-Algorithm
,	O
DSA	O
,	O
Triple	B-Algorithm
DES	I-Algorithm
and	O
SHA-1	B-Algorithm
.	O
</s>
<s>
In	O
addition	O
to	O
these	O
algorithms	O
,	O
the	O
standard	O
recommends	O
RSA	B-Architecture
as	O
described	O
in	O
PKCS	O
#1	O
v1.5	O
for	O
encryption	O
and	O
signing	O
,	O
as	O
well	O
as	O
AES-128	B-Algorithm
,	O
CAST-128	B-Algorithm
and	O
IDEA	B-Algorithm
.	O
</s>
<s>
The	O
standard	O
was	O
extended	O
to	O
support	O
Camellia	B-Algorithm
cipher	O
by	O
RFC	O
5581	O
in	O
2009	O
,	O
and	O
signing	O
and	O
key	O
exchange	O
based	O
on	O
Elliptic	O
Curve	O
Cryptography	O
(	O
ECC	O
)	O
(	O
i.e.	O
</s>
<s>
ECDSA	O
and	O
ECDH	B-Protocol
)	O
by	O
RFC	O
6637	O
in	O
2012	O
.	O
</s>
<s>
The	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
has	O
developed	O
its	O
own	O
OpenPGP-compliant	O
software	O
suite	O
called	O
GNU	B-Application
Privacy	I-Application
Guard	I-Application
,	O
freely	O
available	O
together	O
with	O
all	O
source	O
code	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
and	O
is	O
maintained	O
separately	O
from	O
several	O
graphical	B-Application
user	I-Application
interfaces	I-Application
that	O
interact	O
with	O
the	O
GnuPG	B-Application
library	O
for	O
encryption	O
,	O
decryption	O
,	O
and	O
signing	O
functions	O
(	O
see	O
KGPG	B-Language
,	O
Seahorse	B-Application
,	O
MacGPG	B-Application
)	O
.	O
</s>
<s>
The	O
development	O
of	O
an	O
open	B-License
source	I-License
OpenPGP-compliant	O
library	O
,	O
OpenPGP.js	O
,	O
written	O
in	O
JavaScript	B-Language
and	O
supported	O
by	O
the	O
Horizon	O
2020	O
Framework	O
Programme	O
of	O
the	O
European	O
Union	O
,	O
has	O
allowed	O
web-based	O
applications	O
to	O
use	O
PGP	B-Application
encryption	I-Application
in	O
the	O
web	O
browser	O
.	O
</s>
<s>
The	O
open	B-License
source	I-License
office	O
suite	O
LibreOffice	B-Application
implemented	O
document	O
signing	O
with	O
OpenPGP	O
as	O
of	O
version	O
5.4.0	O
on	O
Linux	B-Application
.	O
</s>
<s>
In	O
October	O
2017	O
,	O
the	O
ROCA	O
vulnerability	O
was	O
announced	O
,	O
which	O
affects	O
RSA	B-Architecture
keys	O
generated	O
by	O
buggy	O
Infineon	O
firmware	O
used	O
on	O
Yubikey	O
4	O
tokens	O
,	O
often	O
used	O
with	O
PGP	O
.	O
</s>
