<s>
OpenSSL	O
is	O
a	O
software	B-Library
library	I-Library
for	O
applications	O
that	O
provide	O
secure	O
communications	O
over	O
computer	B-Architecture
networks	I-Architecture
against	O
eavesdropping	O
or	O
need	O
to	O
identify	O
the	O
party	O
at	O
the	O
other	O
end	O
.	O
</s>
<s>
It	O
is	O
widely	O
used	O
by	O
Internet	O
servers	B-Application
,	O
including	O
the	O
majority	O
of	O
HTTPS	B-Protocol
websites	O
.	O
</s>
<s>
OpenSSL	O
contains	O
an	O
open-source	B-Application
implementation	O
of	O
the	O
SSL	B-Protocol
and	I-Protocol
TLS	I-Protocol
protocols	O
.	O
</s>
<s>
The	O
core	O
library	B-Library
,	O
written	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
,	O
implements	O
basic	O
cryptographic	O
functions	O
and	O
provides	O
various	O
utility	O
functions	O
.	O
</s>
<s>
Wrappers	O
allowing	O
the	O
use	O
of	O
the	O
OpenSSL	O
library	B-Library
in	O
a	O
variety	O
of	O
computer	O
languages	O
are	O
available	O
.	O
</s>
<s>
OpenSSL	O
is	O
available	O
for	O
most	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
including	O
Linux	B-Application
,	O
macOS	B-Application
,	O
and	O
BSD	B-Operating_System
)	O
,	O
Microsoft	B-Application
Windows	I-Application
and	O
OpenVMS	B-Operating_System
.	O
</s>
<s>
It	O
is	O
based	O
on	O
a	O
fork	B-Application
of	O
SSLeay	B-Protocol
by	O
Eric	O
Andrew	O
Young	O
and	O
Tim	O
Hudson	O
,	O
which	O
unofficially	O
ended	O
development	O
on	O
December	O
17	O
,	O
1998	O
,	O
when	O
Young	O
and	O
Hudson	O
both	O
went	O
to	O
work	O
for	O
RSA	B-Architecture
Security	O
.	O
</s>
<s>
Development	O
of	O
TLS	B-Protocol
1.3	I-Protocol
was	O
sponsored	O
by	O
Akamai	B-Application
.	O
</s>
<s>
(	O
Perfect	O
forward	O
secrecy	O
is	O
supported	O
using	O
elliptic	B-Protocol
curve	I-Protocol
Diffie	I-Protocol
–	I-Protocol
Hellman	I-Protocol
since	O
version	O
1.0	O
.	O
)	O
</s>
<s>
The	O
FIPS	O
Object	O
Module	O
2.0	O
remained	O
FIPS	O
140-2	O
validated	O
in	O
several	O
formats	O
until	O
September	O
1	O
,	O
2020	O
,	O
when	O
NIST	O
deprecated	O
the	O
usage	O
of	O
FIPS	O
186-2	O
for	O
Digital	B-Algorithm
Signature	I-Algorithm
Standard	I-Algorithm
and	O
designated	O
all	O
non-compliant	O
modules	O
as	O
'	O
Historical	O
 '	O
.	O
</s>
<s>
Many	O
'	O
private	O
label	O
 '	O
OpenSSL-based	O
validations	O
and	O
clones	O
created	O
by	O
consultants	O
were	O
also	O
moved	O
to	O
the	O
Historical	O
List	O
,	O
although	O
some	O
FIPS	O
validated	O
modules	O
with	O
replacement	O
compatibility	O
avoided	O
the	O
deprecation	O
,	O
such	O
as	O
BoringCrypto	O
from	O
Google	B-Application
and	O
CryptoComply	O
from	O
SafeLogic	O
.	O
</s>
<s>
OpenSSL	O
was	O
dual-licensed	O
under	O
the	O
OpenSSL	B-License
License	I-License
and	O
the	O
SSLeay	B-Protocol
License	O
,	O
which	O
means	O
that	O
the	O
terms	O
of	O
either	O
licenses	O
can	O
be	O
used	O
.	O
</s>
<s>
The	O
OpenSSL	B-License
License	I-License
is	O
Apache	B-Application
License	I-Application
1.0	O
and	O
SSLeay	B-Protocol
License	O
bears	O
some	O
similarity	O
to	O
a	O
4-clause	O
BSD	B-Operating_System
License	I-Operating_System
.	O
</s>
<s>
As	O
the	O
OpenSSL	B-License
License	I-License
was	O
Apache	B-Application
License	I-Application
1.0	O
,	O
but	O
not	O
Apache	B-Application
License	I-Application
2.0	I-Application
,	O
it	O
requires	O
the	O
phrase	O
"	O
this	O
product	O
includes	O
software	O
developed	O
by	O
the	O
OpenSSL	O
Project	O
for	O
use	O
in	O
the	O
OpenSSL	O
Toolkit	O
"	O
to	O
appear	O
in	O
advertising	O
material	O
and	O
any	O
redistributions	O
(	O
Sections	O
3	O
and	O
6	O
of	O
the	O
OpenSSL	B-License
License	I-License
)	O
.	O
</s>
<s>
Due	O
to	O
this	O
restriction	O
,	O
the	O
OpenSSL	B-License
License	I-License
and	O
the	O
Apache	B-Application
License	I-Application
1.0	O
are	O
incompatible	O
with	O
the	O
GNU	B-License
GPL	I-License
.	O
</s>
<s>
Some	O
GPL	B-License
developers	O
have	O
added	O
an	O
OpenSSL	O
exception	O
to	O
their	O
licenses	O
that	O
specifically	O
permits	O
using	O
OpenSSL	O
with	O
their	O
system	O
.	O
</s>
<s>
GNU	B-Protocol
Wget	I-Protocol
and	O
climm	B-Protocol
both	O
use	O
such	O
exceptions	O
.	O
</s>
<s>
Some	O
packages	O
(	O
like	O
Deluge	B-Language
)	O
explicitly	O
modify	O
the	O
GPL	B-License
license	I-License
by	O
adding	O
an	O
extra	O
section	O
at	O
the	O
beginning	O
of	O
the	O
license	O
documenting	O
the	O
exception	O
.	O
</s>
<s>
Other	O
packages	O
use	O
the	O
LGPL-licensed	O
GnuTLS	B-Application
,	O
BSD-licensed	O
Botan	B-Protocol
,	O
or	O
MPL-licensed	O
NSS	B-Protocol
,	O
which	O
perform	O
the	O
same	O
task	O
.	O
</s>
<s>
OpenSSL	O
announced	O
in	O
August	O
2015	O
that	O
it	O
would	O
require	O
most	O
contributors	O
to	O
sign	O
a	O
Contributor	O
License	O
Agreement	O
(	O
CLA	O
)	O
,	O
and	O
that	O
OpenSSL	O
would	O
eventually	O
be	O
relicensed	O
under	O
the	O
terms	O
of	O
Apache	B-Application
License	I-Application
2.0	O
.	O
</s>
<s>
On	O
7	O
September	O
2021	O
,	O
OpenSSL	O
3.0.0	O
was	O
released	O
under	O
the	O
Apache	B-Application
License	I-Application
2.0	I-Application
.	O
</s>
<s>
OpenSSL	O
0.9.6k	O
has	O
a	O
bug	B-Error_Name
where	O
certain	O
ASN.1	B-Protocol
sequences	O
triggered	O
a	O
large	O
number	O
of	O
recursions	O
on	O
Windows	O
machines	O
,	O
discovered	O
on	O
November	O
4	O
,	O
2003	O
.	O
</s>
<s>
Being	O
able	O
to	O
send	O
arbitrary	O
large	O
numbers	O
of	O
ASN.1	B-Protocol
sequences	O
would	O
cause	O
OpenSSL	O
to	O
crash	O
as	O
a	O
result	O
.	O
</s>
<s>
It	O
was	O
also	O
possible	O
that	O
some	O
applications	O
expose	O
the	O
contents	O
of	O
parsed	O
OCSP	B-Protocol
extensions	O
,	O
leading	O
to	O
an	O
attacker	O
being	O
able	O
to	O
read	O
the	O
contents	O
of	O
memory	O
that	O
came	O
after	O
the	O
ClientHello	O
.	O
</s>
<s>
While	O
not	O
directly	O
affecting	O
the	O
SSL/TLS	B-Protocol
code	O
of	O
OpenSSL	O
,	O
any	O
application	O
that	O
was	O
using	O
ASN.1	B-Protocol
functions	O
(	O
particularly	O
d2i_X509	O
and	O
d2i_PKCS12	O
)	O
were	O
also	O
not	O
affected	O
.	O
</s>
<s>
In	O
handling	O
CBC	O
cipher-suites	O
in	O
SSL	O
,	O
TLS	B-Protocol
,	O
and	O
DTLS	O
,	O
OpenSSL	O
was	O
found	O
vulnerable	O
to	O
a	O
timing	O
attack	O
during	O
the	O
MAC	O
processing	O
.	O
</s>
<s>
To	O
keep	O
the	O
Valgrind	B-Application
analysis	O
tool	O
from	O
issuing	O
associated	O
warnings	O
,	O
a	O
maintainer	O
of	O
the	O
Debian	O
distribution	O
applied	O
a	O
patch	O
to	O
Debian	O
's	O
variant	O
of	O
the	O
OpenSSL	O
suite	O
,	O
which	O
inadvertently	O
broke	O
its	O
random	O
number	O
generator	O
by	O
limiting	O
the	O
overall	O
number	O
of	O
private	B-Application
keys	I-Application
it	O
could	O
generate	O
to	O
32,768	O
.	O
</s>
<s>
The	O
broken	O
version	O
was	O
included	O
in	O
the	O
Debian	O
release	O
of	O
September	O
17	O
,	O
2006	O
(	O
version	O
0.9.8c-1	O
)	O
,	O
also	O
compromising	O
other	O
Debian-based	O
distributions	O
,	O
for	O
example	O
Ubuntu	B-Operating_System
.	O
</s>
<s>
OpenSSL	O
versions	O
1.0.1	O
through	O
1.0.1f	O
have	O
a	O
severe	O
memory	O
handling	O
bug	B-Error_Name
in	O
their	O
implementation	O
of	O
the	O
TLS	B-Protocol
Heartbeat	B-Operating_System
Extension	O
that	O
could	O
be	O
used	O
to	O
reveal	O
up	O
to	O
64KB	O
of	O
the	O
application	O
's	O
memory	O
with	O
every	O
heartbeat	B-Operating_System
(	O
)	O
.	O
</s>
<s>
By	O
reading	O
the	O
memory	O
of	O
the	O
web	B-Application
server	I-Application
,	O
attackers	O
could	O
access	O
sensitive	O
data	O
,	O
including	O
the	O
server	O
's	O
private	B-Application
key	I-Application
.	O
</s>
<s>
Knowledge	O
of	O
the	O
private	B-Application
key	I-Application
could	O
also	O
allow	O
an	O
attacker	O
to	O
mount	O
a	O
man-in-the-middle	O
attack	O
against	O
any	O
future	O
communications	O
.	O
</s>
<s>
The	O
vulnerability	O
might	O
also	O
reveal	O
unencrypted	O
parts	O
of	O
other	O
users	O
 '	O
sensitive	O
requests	O
and	O
responses	O
,	O
including	O
session	O
cookies	O
and	O
passwords	O
,	O
which	O
might	O
allow	O
attackers	O
to	O
hijack	B-Protocol
the	I-Protocol
identity	I-Protocol
of	O
another	O
user	O
of	O
the	O
service	O
.	O
</s>
<s>
At	O
its	O
disclosure	O
on	O
April	O
7	O
,	O
2014	O
,	O
around	O
17%	O
or	O
half	O
a	O
million	O
of	O
the	O
Internet	O
's	O
secure	O
web	B-Application
servers	I-Application
certified	O
by	O
trusted	B-Architecture
authorities	I-Architecture
were	O
believed	O
to	O
have	O
been	O
vulnerable	O
to	O
the	O
attack	O
.	O
</s>
<s>
However	O
,	O
Heartbleed	B-Error_Name
can	O
affect	O
both	O
the	O
server	O
and	O
client	O
.	O
</s>
<s>
Servers	B-Application
are	O
only	O
known	O
to	O
be	O
vulnerable	O
in	O
OpenSSL	O
1.0.1	O
and	O
1.0.2-beta1	O
.	O
</s>
<s>
Users	O
of	O
OpenSSL	O
servers	B-Application
earlier	O
than	O
1.0.1	O
are	O
advised	O
to	O
upgrade	O
as	O
a	O
precaution	O
.	O
</s>
<s>
OpenSSL	O
classified	O
the	O
bug	B-Error_Name
as	O
a	O
high-severity	O
issue	O
,	O
noting	O
version	O
1.0.2	O
was	O
found	O
vulnerable	O
.	O
</s>
<s>
This	O
vulnerability	O
(	O
)	O
allows	O
,	O
when	O
some	O
particular	O
circumstances	O
are	O
met	O
,	O
to	O
recover	O
the	O
OpenSSL	O
server	O
's	O
private	O
Diffie	B-Protocol
–	I-Protocol
Hellman	I-Protocol
key	O
.	O
</s>
<s>
OpenSSL	O
classified	O
the	O
bug	B-Error_Name
as	O
a	O
high-severity	O
issue	O
,	O
noting	O
only	O
version	O
1.0.2	O
was	O
found	O
vulnerable	O
.	O
</s>
<s>
In	O
2009	O
,	O
after	O
frustrations	O
with	O
the	O
original	O
OpenSSL	O
API	O
,	O
Marco	O
Peereboom	O
,	O
an	O
OpenBSD	B-Operating_System
developer	O
at	O
the	O
time	O
,	O
forked	O
the	O
original	O
API	O
by	O
creating	O
Agglomerated	O
SSL	O
(	O
assl	O
)	O
,	O
which	O
reuses	O
OpenSSL	O
API	O
under	O
the	O
hood	O
,	O
but	O
provides	O
a	O
much	O
simpler	O
external	O
interface	O
.	O
</s>
<s>
It	O
has	O
since	O
been	O
deprecated	O
in	O
light	O
of	O
the	O
LibreSSL	B-Language
fork	B-Application
circa	O
2016	O
.	O
</s>
<s>
In	O
April	O
2014	O
in	O
the	O
wake	O
of	O
Heartbleed	B-Error_Name
,	O
members	O
of	O
the	O
OpenBSD	B-Operating_System
project	I-Operating_System
forked	O
OpenSSL	O
starting	O
with	O
the	O
1.0.1g	O
branch	O
,	O
to	O
create	O
a	O
project	O
named	O
LibreSSL	B-Language
.	O
</s>
<s>
In	O
the	O
first	O
week	O
of	O
pruning	O
the	O
OpenSSL	O
's	O
codebase	B-General_Concept
,	O
more	O
than	O
90,000	O
lines	O
of	O
C	B-Language
code	O
had	O
been	O
removed	O
from	O
the	O
fork	B-Application
.	O
</s>
<s>
In	O
June	O
2014	O
,	O
Google	B-Application
announced	O
its	O
own	O
fork	B-Application
of	O
OpenSSL	O
dubbed	O
BoringSSL	O
.	O
</s>
<s>
Google	B-Application
plans	O
to	O
co-operate	O
with	O
OpenSSL	O
and	O
LibreSSL	B-Language
developers	O
.	O
</s>
<s>
Google	B-Application
has	O
since	O
developed	O
a	O
new	O
library	B-Library
,	O
Tink	O
,	O
based	O
on	O
BoringSSL	O
.	O
</s>
<s>
While	O
LTS	O
(	O
long	O
term	O
supported	O
)	O
releases	O
are	O
maintained	O
for	O
5	O
years	O
,	O
accumulated	O
delays	O
in	O
release	O
time	O
frames	O
tend	O
to	O
force	O
operating	B-General_Concept
system	I-General_Concept
vendors	O
to	O
stay	O
on	O
the	O
last	O
supported	O
release	O
longer	O
,	O
leaving	O
less	O
margin	O
when	O
the	O
new	O
version	O
is	O
available	O
.	O
</s>
<s>
While	O
the	O
QUIC	B-Protocol
transport	O
layer	O
was	O
being	O
worked	O
on	O
to	O
support	O
the	O
third	O
version	O
of	O
the	O
HTTP	B-Protocol
protocol	I-Protocol
,	O
it	O
was	O
proposed	O
to	O
use	O
TLS	B-Protocol
to	O
provide	O
security	O
,	O
and	O
identified	O
that	O
some	O
adaptations	O
to	O
TLS	B-Protocol
libraries	O
would	O
be	O
needed	O
.	O
</s>
<s>
Such	O
modifications	O
were	O
brought	O
to	O
BoringSSL	O
which	O
was	O
the	O
library	B-Library
being	O
primarily	O
used	O
by	O
QUIC	B-Protocol
developers	O
by	O
then	O
,	O
and	O
later	O
ported	O
to	O
other	O
libraries	O
.	O
</s>
<s>
Finally	O
more	O
than	O
one	O
year	O
after	O
planned	O
release	O
of	O
3.0	O
which	O
was	O
still	O
not	O
coming	O
,	O
a	O
team	O
of	O
volunteers	O
from	O
Akamai	B-Application
and	O
Microsoft	O
decided	O
to	O
fork	B-Application
the	O
project	O
as	O
QuicTLS	O
and	O
support	O
these	O
patches	O
on	O
top	O
of	O
the	O
OpenSSL	O
code	O
in	O
order	O
to	O
unblock	O
QUIC	B-Protocol
development	O
.	O
</s>
<s>
Finally	O
after	O
OpenSSL	O
3.0	O
was	O
finally	O
released	O
,	O
the	O
QUIC	B-Protocol
patch	O
set	O
was	O
reconsidered	O
and	O
decided	O
against	O
,	O
causing	O
tens	O
to	O
hundreds	O
of	O
reactions	O
of	O
disappointment	O
among	O
the	O
community	O
.	O
</s>
<s>
The	O
pull	O
request	O
was	O
closed	O
,	O
while	O
users	O
felt	O
the	O
need	O
to	O
publicly	O
express	O
their	O
disappointment	O
,	O
or	O
beg	O
operating	B-General_Concept
system	I-General_Concept
vendors	O
to	O
support	O
the	O
alternative	O
QuicTLS	O
fork	B-Application
,	O
or	O
seek	O
for	O
alternative	O
solutions	O
.	O
</s>
<s>
Finally	O
Rich	O
Salz	O
,	O
co-founder	O
of	O
the	O
QuicTLS	O
fork	B-Application
,	O
announced	O
his	O
interest	O
in	O
seeing	O
an	O
Apache	O
project	O
forked	O
from	O
QuicTLS	O
.	O
</s>
<s>
As	O
of	O
25	O
February	O
2023	O
there	O
is	O
still	O
no	O
QUIC-compatible	O
long-term	O
supported	O
TLS	B-Protocol
library	B-Library
available	O
by	O
default	O
in	O
operating	B-General_Concept
systems	I-General_Concept
without	O
requiring	O
end-users	O
to	O
rebuild	O
it	O
themselves	O
from	O
sources	O
.	O
</s>
