<s>
ssh-keygen	B-Protocol
is	O
a	O
standard	O
component	O
of	O
the	O
Secure	B-Protocol
Shell	I-Protocol
(	O
SSH	B-Protocol
)	O
protocol	O
suite	O
found	O
on	O
Unix	B-Application
,	O
Unix-like	B-Operating_System
and	O
Microsoft	B-Application
Windows	I-Application
computer	O
systems	O
used	O
to	O
establish	O
secure	B-Protocol
shell	I-Protocol
sessions	O
between	O
remote	O
computers	O
over	O
insecure	O
networks	O
,	O
through	O
the	O
use	O
of	O
various	O
cryptographic	O
techniques	O
.	O
</s>
<s>
The	O
ssh-keygen	B-Protocol
utility	O
is	O
used	O
to	O
generate	O
,	O
manage	O
,	O
and	O
convert	O
authentication	O
keys	O
.	O
</s>
<s>
ssh-keygen	B-Protocol
is	O
able	O
to	O
generate	O
a	O
key	O
using	O
one	O
of	O
three	O
different	O
digital	O
signature	O
algorithms	O
.	O
</s>
<s>
With	O
the	O
help	O
of	O
the	O
ssh-keygen	B-Protocol
tool	O
,	O
a	O
user	O
can	O
create	O
passphrase	O
keys	O
for	O
any	O
of	O
these	O
key	O
types	O
.	O
</s>
<s>
These	O
keys	O
differ	O
from	O
keys	O
used	O
by	O
the	O
related	O
tool	O
GNU	B-Application
Privacy	I-Application
Guard	I-Application
.	O
</s>
<s>
OpenSSH-based	O
client	O
and	O
server	O
programs	O
have	O
been	O
included	O
in	O
Windows	B-Operating_System
10	I-Operating_System
since	O
version	O
1803	O
.	O
</s>
<s>
The	O
SSH	B-Protocol
client	O
and	O
key	O
agent	O
are	O
enabled	O
and	O
available	O
by	O
default	O
and	O
the	O
SSH	B-Protocol
server	O
is	O
an	O
optional	O
Feature-on-Demand	O
.	O
</s>
<s>
Originally	O
,	O
with	O
SSH	B-Protocol
protocol	O
version	O
1	O
(	O
now	O
deprecated	O
)	O
only	O
the	O
RSA	B-Architecture
algorithm	I-Architecture
was	O
supported	O
.	O
</s>
<s>
As	O
of	O
2016	O
,	O
RSA	B-Architecture
is	O
still	O
considered	O
strong	O
,	O
but	O
the	O
recommended	O
key	O
length	O
has	O
increased	O
over	O
time	O
.	O
</s>
<s>
The	O
SSH	B-Protocol
protocol	O
version	O
2	O
additionally	O
introduced	O
support	O
for	O
the	O
DSA	O
algorithm	O
.	O
</s>
<s>
DSA	O
is	O
now	O
considered	O
weak	O
and	O
was	O
disabled	O
in	O
OpenSSH	B-Language
7.0	O
.	O
</s>
<s>
Subsequently	O
,	O
OpenSSH	B-Language
added	O
support	O
for	O
a	O
third	O
digital	O
signature	O
algorithm	O
,	O
ECDSA	O
(	O
this	O
key	O
format	O
no	O
longer	O
uses	O
the	O
previous	O
PEM	B-Protocol
file	I-Protocol
format	O
for	O
private	O
keys	O
,	O
nor	O
does	O
it	O
depend	O
upon	O
the	O
OpenSSL	B-Language
library	O
to	O
provide	O
the	O
cryptographic	O
implementation	O
)	O
.	O
</s>
<s>
The	O
syntax	O
of	O
the	O
ssh-keygen	B-Protocol
command	B-Application
is	O
as	O
follows	O
:	O
</s>
<s>
Some	O
important	O
options	O
of	O
the	O
ssh-keygen	B-Protocol
command	B-Application
are	O
as	O
follows	O
:	O
</s>
<s>
ssh-keygen	B-Protocol
command	B-Application
options	O
description	O
-b	O
bits	O
Specifies	O
the	O
number	O
of	O
bits	O
in	O
the	O
key	O
to	O
create	O
.	O
</s>
<s>
The	O
default	O
length	O
is	O
3072	O
bits	O
(	O
RSA	B-Architecture
)	O
or	O
256	O
bits	O
(	O
ECDSA	O
)	O
.	O
</s>
<s>
-C	O
comment	O
Provides	O
custom	O
key	O
comment	O
(	O
which	O
will	O
be	O
appended	O
at	O
the	O
end	O
of	O
the	O
public	O
key	O
)	O
.	O
</s>
<s>
-t	O
Specifies	O
the	O
type	O
of	O
key	O
to	O
create	O
(	O
e.g.	O
,	O
rsa	B-Architecture
)	O
.	O
</s>
<s>
-o	O
Use	O
the	O
new	O
OpenSSH	B-Language
format	O
.	O
</s>
<s>
-q	O
quiets	O
ssh-keygen	B-Protocol
.	O
</s>
<s>
-l	O
Dumps	O
the	O
key	O
's	O
fingerprint	O
in	O
SHA-2	B-Algorithm
(	O
or	O
MD5	B-Algorithm
)	O
format	O
.	O
</s>
<s>
The	O
ssh-keygen	B-Protocol
utility	O
uses	O
various	O
files	O
for	O
storing	O
public	O
and	O
private	O
keys	O
.	O
</s>
<s>
The	O
files	O
used	O
by	O
ssh-keygen	B-Protocol
utility	O
are	O
as	O
follows	O
:	O
</s>
<s>
$	O
HOME/.ssh/identity	O
:	O
The	O
$	O
HOME/.ssh/identity	O
file	O
contains	O
the	O
RSA	B-Architecture
private	O
key	O
when	O
using	O
the	O
SSH	B-Protocol
protocol	O
version	O
1	O
.	O
</s>
<s>
$	O
HOME/.ssh/identity.pub	O
:	O
The	O
$	O
HOME/.ssh/identity.pub	O
file	O
contains	O
the	O
RSA	B-Architecture
public	O
key	O
for	O
authentication	O
when	O
you	O
are	O
using	O
the	O
SSH	B-Protocol
protocol	O
version	O
1	O
.	O
</s>
<s>
A	O
user	O
should	O
copy	O
its	O
contents	O
in	O
the	O
$	O
HOME/.ssh/authorized_keys	O
file	O
of	O
the	O
remote	O
system	O
where	O
a	O
user	O
wants	O
to	O
log	O
in	O
using	O
RSA	B-Architecture
authentication	O
.	O
</s>
<s>
$	O
HOME/.ssh/id_dsa	O
:	O
The	O
$	O
HOME/.ssh/id_dsa	O
file	O
contains	O
the	O
protocol	O
version	O
2	O
DSA	O
authentication	O
identity	O
of	O
the	O
user	O
.	O
</s>
<s>
$	O
HOME/.ssh/id_dsa.pub	O
:	O
The	O
$	O
HOME/.ssh/id_dsa.pub	O
file	O
contains	O
the	O
DSA	O
public	O
key	O
for	O
authentication	O
when	O
you	O
are	O
using	O
the	O
SSH	B-Protocol
protocol	O
version	O
2	O
.	O
</s>
<s>
A	O
user	O
should	O
copy	O
its	O
contents	O
in	O
the	O
$	O
HOME/.ssh/authorized_keys	O
file	O
of	O
the	O
remote	O
system	O
where	O
a	O
user	O
wants	O
to	O
log	O
in	O
using	O
DSA	O
authentication	O
.	O
</s>
<s>
$	O
HOME/.ssh/id_rsa	O
:	O
The	O
$	O
HOME/.ssh/id_rsa	O
file	O
contains	O
the	O
protocol	O
version	O
2	O
RSA	B-Architecture
authentication	O
identity	O
of	O
the	O
user	O
.	O
</s>
<s>
$	O
HOME/.ssh/id_rsa.pub	O
:	O
The	O
$	O
HOME/.ssh/id_rsa.pub	O
file	O
contains	O
the	O
protocol	O
version	O
2	O
RSA	B-Architecture
public	O
key	O
for	O
authentication	O
.	O
</s>
<s>
The	O
contents	O
of	O
this	O
file	O
should	O
be	O
added	O
to	O
$	O
HOME/.ssh/authorized_keys	O
on	O
all	O
computers	O
where	O
a	O
user	O
wishes	O
to	O
log	O
in	O
using	O
public	O
key	O
authentication	O
.	O
</s>
