-.\" $OpenBSD: ssh-keygen.1,v 1.67 2005/03/14 10:09:03 dtucker Exp $
+.\" $OpenBSD: ssh-keygen.1,v 1.50 2001/10/25 21:14:32 markus Exp $
.\"
.\" -*- nroff -*-
.\"
.Nd authentication key generation, management and conversion
.Sh SYNOPSIS
.Nm ssh-keygen
-.Bk -words
.Op Fl q
.Op Fl b Ar bits
-.Fl t Ar type
+.Op Fl t Ar type
.Op Fl N Ar new_passphrase
.Op Fl C Ar comment
.Op Fl f Ar output_keyfile
-.Ek
.Nm ssh-keygen
.Fl p
.Op Fl P Ar old_passphrase
.Nm ssh-keygen
.Fl D Ar reader
.Nm ssh-keygen
-.Fl F Ar hostname
-.Op Fl f Ar known_hosts_file
-.Nm ssh-keygen
-.Fl H
-.Op Fl f Ar known_hosts_file
-.Nm ssh-keygen
-.Fl R Ar hostname
-.Op Fl f Ar known_hosts_file
-.Nm ssh-keygen
.Fl U Ar reader
.Op Fl f Ar input_keyfile
-.Nm ssh-keygen
-.Fl r Ar hostname
-.Op Fl f Ar input_keyfile
-.Op Fl g
-.Nm ssh-keygen
-.Fl G Ar output_file
-.Op Fl v
-.Op Fl b Ar bits
-.Op Fl M Ar memory
-.Op Fl S Ar start_point
-.Nm ssh-keygen
-.Fl T Ar output_file
-.Fl f Ar input_file
-.Op Fl v
-.Op Fl a Ar num_trials
-.Op Fl W Ar generator
.Sh DESCRIPTION
.Nm
generates, manages and converts authentication keys for
.Xr ssh 1 .
.Nm
-can create RSA keys for use by SSH protocol version 1 and RSA or DSA
-keys for use by SSH protocol version 2.
-The type of key to be generated is specified with the
+defaults to generating a RSA1 key for use by SSH protocol version 1.
+Specifying the
.Fl t
-option.
-.Pp
-.Nm
-is also used to generate groups for use in Diffie-Hellman group
-exchange (DH-GEX).
-See the
-.Sx MODULI GENERATION
-section for details.
+option instead creates a key for use by SSH protocol version 2.
.Pp
Normally each user wishing to use SSH
with RSA or DSA authentication runs this once to create the authentication
The passphrase may be empty to indicate no passphrase
(host keys must have an empty passphrase), or it may be a string of
arbitrary length.
-A passphrase is similar to a password, except it can be a phrase with a
-series of words, punctuation, numbers, whitespace, or any string of
-characters you want.
-Good passphrases are 10-30 characters long, are
+Good passphrases are 10-30 characters long and are
not simple sentences or otherwise easily guessable (English
prose has only 1-2 bits of entropy per character, and provides very bad
-passphrases), and contain a mix of upper and lowercase letters,
-numbers, and non-alphanumeric characters.
+passphrases).
The passphrase can be changed later by using the
.Fl p
option.
.Pp
The options are as follows:
.Bl -tag -width Ds
-.It Fl a Ar trials
-Specifies the number of primality tests to perform when screening DH-GEX
-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.
+Generally 1024 bits is considered sufficient, and key sizes
+above that no longer improve security but make things slower.
The default is 1024 bits.
-.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
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 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
For RSA and DSA keys
.Nm
tries to find the matching public key file and prints its 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 R Ar hostname
-Removes all keys belonging to
-.Ar hostname
-from a
-.Pa known_hosts
-file.
-This option is useful to delete hashed hosts (see the
-.Fl H
-option above).
-.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 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 key to create.
+Specifies the type of the key to create.
The possible values are
.Dq rsa1
for protocol version 1 and
or
.Dq dsa
for protocol version 2.
+The default is
+.Dq rsa1 .
+.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 N Ar new_passphrase
+Provides the new passphrase.
+.It Fl P Ar passphrase
+Provides the (old) passphrase.
.It Fl U Ar reader
Upload an existing RSA private key into the smartcard in
.Ar reader .
-.It Fl v
-Verbose mode.
-Causes
-.Nm
-to print debugging messages about its progress.
-This is helpful for debugging moduli generation.
-Multiple
-.Fl v
-options increase the verbosity.
-The maximum is 3.
-.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
-may be used to generate groups for the Diffie-Hellman Group Exchange
-(DH-GEX) protocol.
-Generating these groups is a two-step process: first, candidate
-primes are generated using a fast, but memory intensive process.
-These candidate primes are then tested for suitability (a CPU-intensive
-process).
-.Pp
-Generation of primes is performed using the
-.Fl G
-option.
-The desired length of the primes may be specified by the
-.Fl b
-option.
-For example:
-.Pp
-.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.
-This may be overridden using the
-.Fl S
-option, which specifies a different start point (in hex).
-.Pp
-Once a set of candidates have been generated, they must be tested for
-suitability.
-This may be performed using the
-.Fl T
-option.
-In this mode
-.Nm
-will read candidates from standard input (or a file specified using the
-.Fl f
-option).
-For example:
-.Pp
-.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
-.Fl a
-option.
-The DH generator value will be chosen automatically for the
-prime under consideration.
-If a specific generator is desired, it may be requested using the
-.Fl W
-option.
-Valid generator values are 2, 3, and 5.
-.Pp
-Screened DH groups may be installed in
-.Pa /etc/moduli .
-It is important that this file contains moduli of a range of bit lengths and
-that both ends of a connection share common moduli.
.Sh FILES
.Bl -tag -width Ds
.It Pa $HOME/.ssh/identity
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 /etc/moduli
-Contains Diffie-Hellman groups used for DH-GEX.
-The file format is described in
-.Xr moduli 5 .
.El
+.Sh AUTHORS
+OpenSSH is a derivative of the original and free
+ssh 1.2.12 release by Tatu Ylonen.
+Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
+Theo de Raadt and Dug Song
+removed many bugs, re-added newer features and
+created OpenSSH.
+Markus Friedl contributed the support for SSH
+protocol versions 1.5 and 2.0.
.Sh SEE ALSO
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1 ,
-.Xr moduli 5 ,
.Xr sshd 8
.Rs
.%A J. Galbraith
.%D March 2001
.%O work in progress material
.Re
-.Sh AUTHORS
-OpenSSH is a derivative of the original and free
-ssh 1.2.12 release by Tatu Ylonen.
-Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
-Theo de Raadt and Dug Song
-removed many bugs, re-added newer features and
-created OpenSSH.
-Markus Friedl contributed the support for SSH
-protocol versions 1.5 and 2.0.
andersk / gssapi-openssh.git / blobdiff