-.\" $OpenBSD: ssh-keygen.1,v 1.65 2005/03/01 15:05:00 jmc Exp $
+.\" $OpenBSD: ssh-keygen.1,v 1.80 2009/10/24 00:48:34 dtucker Exp $
.\"
.\" -*- nroff -*-
.\"
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd September 25, 1999
+.Dd $Mdocdate$
.Dt SSH-KEYGEN 1
.Os
.Sh NAME
.Nm ssh-keygen
.Fl F Ar hostname
.Op Fl f Ar known_hosts_file
+.Op Fl l
.Nm ssh-keygen
.Fl H
.Op Fl f Ar known_hosts_file
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 .
candidates using the
.Fl T
command.
+.It Fl B
+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
Requests changing the comment in the private and public key files.
This operation is only supported for RSA1 keys.
The program will prompt for the file containing the private keys, for
the passphrase if the key has one, and for the new comment.
+.It Fl D Ar reader
+Download the RSA public key stored in the smartcard in
+.Ar reader .
.It Fl e
This option will read a private or public OpenSSH key file and
-print the key in a
-.Sq SECSH Public Key File Format
+print the key in
+RFC 4716 SSH Public Key File Format
to stdout.
This option allows exporting keys for use by several commercial
SSH implementations.
+.It Fl F Ar hostname
+Search for the specified
+.Ar hostname
+in a
+.Pa known_hosts
+file, listing any occurrences found.
+This option is useful to find hashed host names or addresses and may also be
+used in conjunction with the
+.Fl H
+option to print found keys in a hashed format.
+.It Fl f Ar filename
+Specifies the filename of the key file.
+.It Fl G Ar output_file
+Generate candidate primes for DH-GEX.
+These primes must be screened for
+safety (using the
+.Fl T
+option) before use.
.It Fl g
Use generic DNS format when printing fingerprint resource records using the
.Fl r
command.
-.It Fl f Ar filename
-Specifies the filename of the key file.
+.It Fl H
+Hash a
+.Pa known_hosts
+file.
+This replaces all hostnames and addresses with hashed representations
+within the specified file; the original content is moved to a file with
+a .old suffix.
+These hashes may be used normally by
+.Nm ssh
+and
+.Nm sshd ,
+but they do not reveal identifying information should the file's contents
+be disclosed.
+This option will not modify existing hashed hostnames and is therefore safe
+to use on files that mix hashed and non-hashed names.
.It Fl i
This option will read an unencrypted private (or public) key file
in SSH2-compatible format and print an OpenSSH compatible private
(or public) key to stdout.
.Nm
also reads the
-.Sq SECSH Public Key File Format .
+RFC 4716 SSH Public Key File Format.
This option allows importing keys from several commercial
SSH implementations.
.It Fl l
For RSA and DSA keys
.Nm
tries to find the matching public key file and prints its fingerprint.
+If combined with
+.Fl v ,
+an ASCII art representation of the key is supplied with the fingerprint.
+.It Fl M Ar memory
+Specify the amount of memory to use (in megabytes) when generating
+candidate moduli for DH-GEX.
+.It Fl N Ar new_passphrase
+Provides the new passphrase.
+.It Fl P Ar passphrase
+Provides the (old) passphrase.
.It Fl p
Requests changing the passphrase of a private key file instead of
creating a new private key.
Used by
.Pa /etc/rc
when creating a new key.
-.It Fl y
-This option will read a private
-OpenSSH format file and print an OpenSSH public key to stdout.
-.It Fl t Ar type
-Specifies the type of the key to create.
-The possible values are
-.Dq rsa1
-for protocol version 1 and
-.Dq rsa
-or
-.Dq dsa
-for protocol version 2.
-.It Fl B
-Show the bubblebabble digest of specified private or public key file.
-.It Fl C Ar comment
-Provides the new comment.
-.It Fl D Ar reader
-Download the RSA public key stored in the smartcard in
-.Ar reader .
-.It Fl F Ar hostname
-Search for the specified
-.Ar hostname
-in a
-.Pa known_hosts
-file, listing any occurances found.
-This option is useful to find hashed host names or addresses and may also be
-used in conjunction with the
-.Fl H
-option to print found keys in a hashed format.
-.It Fl H
-Hash a
-.Pa known_hosts
-file, printing the result to standard output.
-This replaces all hostnames and addresses with hashed representations.
-These hashes may be used normally by
-.Nm ssh
-and
-.Nm sshd ,
-but they do not reveal identifying information should the file's contents
-be disclosed.
-This option will not modify existing hashed hostnames and is therefore safe
-to use on files that mix hashed and non-hashed names.
.It Fl R Ar hostname
Removes all keys belonging to
.Ar hostname
This option is useful to delete hashed hosts (see the
.Fl H
option above).
-.It Fl G Ar output_file
-Generate candidate primes for DH-GEX.
-These primes must be screened for
-safety (using the
-.Fl T
-option) before use.
-.It Fl M Ar memory
-Specify the amount of memory to use (in megabytes) when generating
-candidate moduli for DH-GEX.
-.It Fl N Ar new_passphrase
-Provides the new passphrase.
-.It Fl P Ar passphrase
-Provides the (old) passphrase.
+.It Fl r Ar hostname
+Print the SSHFP fingerprint resource record named
+.Ar hostname
+for the specified public key file.
.It Fl S Ar start
Specify start point (in hex) when generating candidate moduli for DH-GEX.
.It Fl T Ar output_file
Test DH group exchange candidate primes (generated using the
.Fl G
option) for safety.
-.It Fl W Ar generator
-Specify desired generator when testing candidate moduli for DH-GEX.
+.It Fl t Ar type
+Specifies the type of key to create.
+The possible values are
+.Dq rsa1
+for protocol version 1 and
+.Dq rsa
+or
+.Dq dsa
+for protocol version 2.
.It Fl U Ar reader
Upload an existing RSA private key into the smartcard in
.Ar reader .
.Fl v
options increase the verbosity.
The maximum is 3.
-.It Fl r Ar hostname
-Print the SSHFP fingerprint resource record named
-.Ar hostname
-for the specified public key file.
+.It Fl W Ar generator
+Specify desired generator when testing candidate moduli for DH-GEX.
+.It Fl y
+This option will read a private
+OpenSSH format file and print an OpenSSH public key to stdout.
.El
.Sh MODULI GENERATION
.Nm
option.
For example:
.Pp
-.Dl ssh-keygen -G moduli-2048.candidates -b 2048
+.Dl # ssh-keygen -G moduli-2048.candidates -b 2048
.Pp
By default, the search for primes begins at a random point in the
desired length range.
option).
For example:
.Pp
-.Dl ssh-keygen -T moduli-2048 -f moduli-2048.candidates
+.Dl # ssh-keygen -T moduli-2048 -f moduli-2048.candidates
.Pp
By default, each candidate will be subjected to 100 primality tests.
This may be overridden using the
If a specific generator is desired, it may be requested using the
.Fl W
option.
-Valid generator values are 2, 3 and 5.
+Valid generator values are 2, 3, and 5.
.Pp
Screened DH groups may be installed in
.Pa /etc/moduli .
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
specify a passphrase when generating the key; that passphrase will be
-used to encrypt the private part of this file using 3DES.
+used to encrypt the private part of this file using 128-bit AES.
This file is not automatically accessed by
.Nm
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
specify a passphrase when generating the key; that passphrase will be
-used to encrypt the private part of this file using 3DES.
+used to encrypt the private part of this file using 128-bit AES.
This file is not automatically accessed by
.Nm
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
specify a passphrase when generating the key; that passphrase will be
-used to encrypt the private part of this file using 3DES.
+used to encrypt the private part of this file using 128-bit AES.
This file is not automatically accessed by
.Nm
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.
.Xr moduli 5 ,
.Xr sshd 8
.Rs
-.%A J. Galbraith
-.%A R. Thayer
-.%T "SECSH Public Key File Format"
-.%N draft-ietf-secsh-publickeyfile-01.txt
-.%D March 2001
-.%O work in progress material
+.%R RFC 4716
+.%T "The Secure Shell (SSH) Public Key File Format"
+.%D 2006
.Re
.Sh AUTHORS
OpenSSH is a derivative of the original and free
andersk / openssh.git / blobdiff