-.\" $OpenBSD: ssh-keygen.1,v 1.67 2005/03/14 10:09:03 dtucker Exp $
+.\" $OpenBSD: ssh-keygen.1,v 1.72 2005/11/28 05:16:53 dtucker Exp $
.\"
.\" -*- nroff -*-
.\"
The type of key to be generated is specified with the
.Fl t
option.
+If invoked without any arguments,
+.Nm
+will generate an RSA key for use in SSH protocol 2 connections.
.Pp
.Nm
is also used to generate groups for use in Diffie-Hellman group
Normally each user wishing to use SSH
with RSA or DSA authentication runs this once to create the authentication
key in
-.Pa $HOME/.ssh/identity ,
-.Pa $HOME/.ssh/id_dsa
+.Pa ~/.ssh/identity ,
+.Pa ~/.ssh/id_dsa
or
-.Pa $HOME/.ssh/id_rsa .
+.Pa ~/.ssh/id_rsa .
Additionally, the system administrator may use this to generate host keys,
as seen in
.Pa /etc/rc .
Show the bubblebabble digest of specified private or public key file.
.It Fl b Ar bits
Specifies the number of bits in the key to create.
-Minimum is 512 bits.
-Generally, 1024 bits is considered sufficient.
-The default is 1024 bits.
+For RSA keys, the minimum size is 768 bits and the default is 2048 bits.
+Generally, 2048 bits is considered sufficient.
+DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
.It Fl C Ar comment
Provides a new comment.
.It Fl c
that both ends of a connection share common moduli.
.Sh FILES
.Bl -tag -width Ds
-.It Pa $HOME/.ssh/identity
+.It Pa ~/.ssh/identity
Contains the protocol version 1 RSA authentication identity of the user.
This file should not be readable by anyone but the user.
It is possible to
but it is offered as the default file for the private key.
.Xr ssh 1
will read this file when a login attempt is made.
-.It Pa $HOME/.ssh/identity.pub
+.It Pa ~/.ssh/identity.pub
Contains the protocol version 1 RSA public key for authentication.
The contents of this file should be added to
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
on all machines
where the user wishes to log in using RSA authentication.
There is no need to keep the contents of this file secret.
-.It Pa $HOME/.ssh/id_dsa
+.It Pa ~/.ssh/id_dsa
Contains the protocol version 2 DSA authentication identity of the user.
This file should not be readable by anyone but the user.
It is possible to
but it is offered as the default file for the private key.
.Xr ssh 1
will read this file when a login attempt is made.
-.It Pa $HOME/.ssh/id_dsa.pub
+.It Pa ~/.ssh/id_dsa.pub
Contains the protocol version 2 DSA public key for authentication.
The contents of this file should be added to
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
on all machines
where the user wishes to log in using public key authentication.
There is no need to keep the contents of this file secret.
-.It Pa $HOME/.ssh/id_rsa
+.It Pa ~/.ssh/id_rsa
Contains the protocol version 2 RSA authentication identity of the user.
This file should not be readable by anyone but the user.
It is possible to
but it is offered as the default file for the private key.
.Xr ssh 1
will read this file when a login attempt is made.
-.It Pa $HOME/.ssh/id_rsa.pub
+.It Pa ~/.ssh/id_rsa.pub
Contains the protocol version 2 RSA public key for authentication.
The contents of this file should be added to
-.Pa $HOME/.ssh/authorized_keys
+.Pa ~/.ssh/authorized_keys
on all machines
where the user wishes to log in using public key authentication.
There is no need to keep the contents of this file secret.