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Ben Lindstrom4e366d52001-12-06 16:43:21 +00001.\" $OpenBSD: ssh-keygen.1,v 1.51 2001/11/21 18:49:14 stevesk Exp $
Ben Lindstrom36579d32001-01-29 07:39:26 +00002.\"
Damien Miller32aa1441999-10-29 09:15:49 +10003.\" -*- nroff -*-
4.\"
Damien Miller32aa1441999-10-29 09:15:49 +10005.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller32aa1441999-10-29 09:15:49 +10006.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7.\" All rights reserved
8.\"
Damien Millere4340be2000-09-16 13:29:08 +11009.\" As far as I am concerned, the code I have written for this software
10.\" can be used freely for any purpose. Any derived versions of this
11.\" software must be clearly marked as such, and if the derived work is
12.\" incompatible with the protocol description in the RFC file, it must be
13.\" called by a name other than "ssh" or "Secure Shell".
Damien Miller32aa1441999-10-29 09:15:49 +100014.\"
Damien Millere4340be2000-09-16 13:29:08 +110015.\"
Ben Lindstrom92a2e382001-03-05 06:59:27 +000016.\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
17.\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
18.\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
Damien Millere4340be2000-09-16 13:29:08 +110019.\"
20.\" Redistribution and use in source and binary forms, with or without
21.\" modification, are permitted provided that the following conditions
22.\" are met:
23.\" 1. Redistributions of source code must retain the above copyright
24.\" notice, this list of conditions and the following disclaimer.
25.\" 2. Redistributions in binary form must reproduce the above copyright
26.\" notice, this list of conditions and the following disclaimer in the
27.\" documentation and/or other materials provided with the distribution.
28.\"
29.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
30.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
31.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
32.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
33.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
34.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
38.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Damien Miller32aa1441999-10-29 09:15:49 +100039.\"
40.Dd September 25, 1999
41.Dt SSH-KEYGEN 1
42.Os
43.Sh NAME
44.Nm ssh-keygen
Ben Lindstrom5a707822001-04-22 17:15:46 +000045.Nd authentication key generation, management and conversion
Damien Miller32aa1441999-10-29 09:15:49 +100046.Sh SYNOPSIS
47.Nm ssh-keygen
Damien Miller0bc1bd82000-11-13 22:57:25 +110048.Op Fl q
Damien Miller32aa1441999-10-29 09:15:49 +100049.Op Fl b Ar bits
Damien Miller0bc1bd82000-11-13 22:57:25 +110050.Op Fl t Ar type
Damien Miller32aa1441999-10-29 09:15:49 +100051.Op Fl N Ar new_passphrase
52.Op Fl C Ar comment
Damien Miller1a425f32000-09-02 10:08:09 +110053.Op Fl f Ar output_keyfile
Damien Miller32aa1441999-10-29 09:15:49 +100054.Nm ssh-keygen
55.Fl p
56.Op Fl P Ar old_passphrase
57.Op Fl N Ar new_passphrase
Damien Miller10f6f6b1999-11-17 17:29:08 +110058.Op Fl f Ar keyfile
Damien Miller32aa1441999-10-29 09:15:49 +100059.Nm ssh-keygen
Ben Lindstrom5a707822001-04-22 17:15:46 +000060.Fl i
Damien Miller1a425f32000-09-02 10:08:09 +110061.Op Fl f Ar input_keyfile
Damien Millere247cc42000-05-07 12:03:14 +100062.Nm ssh-keygen
Ben Lindstrom5a707822001-04-22 17:15:46 +000063.Fl e
Damien Miller1a425f32000-09-02 10:08:09 +110064.Op Fl f Ar input_keyfile
Damien Millere247cc42000-05-07 12:03:14 +100065.Nm ssh-keygen
66.Fl y
Damien Miller1a425f32000-09-02 10:08:09 +110067.Op Fl f Ar input_keyfile
Damien Millere247cc42000-05-07 12:03:14 +100068.Nm ssh-keygen
Damien Miller32aa1441999-10-29 09:15:49 +100069.Fl c
70.Op Fl P Ar passphrase
71.Op Fl C Ar comment
Damien Miller10f6f6b1999-11-17 17:29:08 +110072.Op Fl f Ar keyfile
73.Nm ssh-keygen
74.Fl l
Ben Lindstrom8fd372b2001-03-12 03:02:17 +000075.Op Fl f Ar input_keyfile
76.Nm ssh-keygen
77.Fl B
Damien Miller1a425f32000-09-02 10:08:09 +110078.Op Fl f Ar input_keyfile
Ben Lindstroma1ec4a92001-08-06 21:51:34 +000079.Nm ssh-keygen
80.Fl D Ar reader
81.Nm ssh-keygen
82.Fl U Ar reader
83.Op Fl f Ar input_keyfile
Damien Miller22c77262000-04-13 12:26:34 +100084.Sh DESCRIPTION
Damien Miller32aa1441999-10-29 09:15:49 +100085.Nm
Ben Lindstrom5a707822001-04-22 17:15:46 +000086generates, manages and converts authentication keys for
Damien Miller32aa1441999-10-29 09:15:49 +100087.Xr ssh 1 .
Damien Millere247cc42000-05-07 12:03:14 +100088.Nm
Ben Lindstromc65e6a02001-04-23 13:02:16 +000089defaults to generating a RSA1 key for use by SSH protocol version 1.
Ben Lindstromd18c80c2001-08-06 21:00:27 +000090Specifying the
Damien Miller0bc1bd82000-11-13 22:57:25 +110091.Fl t
Ben Lindstrom594e2032001-09-12 18:35:30 +000092option instead creates a key for use by SSH protocol version 2.
Damien Millere247cc42000-05-07 12:03:14 +100093.Pp
Damien Miller32aa1441999-10-29 09:15:49 +100094Normally each user wishing to use SSH
Damien Millere247cc42000-05-07 12:03:14 +100095with RSA or DSA authentication runs this once to create the authentication
Damien Miller32aa1441999-10-29 09:15:49 +100096key in
Ben Lindstrom18a82ac2001-04-11 15:59:35 +000097.Pa $HOME/.ssh/identity ,
98.Pa $HOME/.ssh/id_dsa
Damien Millere247cc42000-05-07 12:03:14 +100099or
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000100.Pa $HOME/.ssh/id_rsa .
Damien Millere247cc42000-05-07 12:03:14 +1000101Additionally, the system administrator may use this to generate host keys,
102as seen in
103.Pa /etc/rc .
Damien Miller32aa1441999-10-29 09:15:49 +1000104.Pp
105Normally this program generates the key and asks for a file in which
Damien Miller450a7a12000-03-26 13:04:51 +1000106to store the private key.
107The public key is stored in a file with the same name but
Damien Miller32aa1441999-10-29 09:15:49 +1000108.Dq .pub
Damien Miller450a7a12000-03-26 13:04:51 +1000109appended.
110The program also asks for a passphrase.
111The passphrase may be empty to indicate no passphrase
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000112(host keys must have an empty passphrase), or it may be a string of
Damien Miller450a7a12000-03-26 13:04:51 +1000113arbitrary length.
Ben Lindstrom4e366d52001-12-06 16:43:21 +0000114A passphrase is similar to a password, except it can be a phrase with a
115series of words, punctuation, numbers, whitespace, or any string of
116characters you want.
117Good passphrases are 10-30 characters long, are
Damien Miller32aa1441999-10-29 09:15:49 +1000118not simple sentences or otherwise easily guessable (English
Ben Lindstrom2a097a42001-06-09 01:13:40 +0000119prose has only 1-2 bits of entropy per character, and provides very bad
Ben Lindstrom4e366d52001-12-06 16:43:21 +0000120passphrases), and contain a mix of upper and lowercase letters,
121numbers, and non-alphanumeric characters.
Damien Miller450a7a12000-03-26 13:04:51 +1000122The passphrase can be changed later by using the
Damien Miller32aa1441999-10-29 09:15:49 +1000123.Fl p
124option.
125.Pp
Damien Miller450a7a12000-03-26 13:04:51 +1000126There is no way to recover a lost passphrase.
127If the passphrase is
Ben Lindstrom594e2032001-09-12 18:35:30 +0000128lost or forgotten, a new key must be generated and copied to the
Damien Miller32aa1441999-10-29 09:15:49 +1000129corresponding public key to other machines.
130.Pp
Ben Lindstrom5a707822001-04-22 17:15:46 +0000131For RSA1 keys,
132there is also a comment field in the key file that is only for
Damien Miller450a7a12000-03-26 13:04:51 +1000133convenience to the user to help identify the key.
134The comment can tell what the key is for, or whatever is useful.
135The comment is initialized to
Damien Miller32aa1441999-10-29 09:15:49 +1000136.Dq user@host
137when the key is created, but can be changed using the
138.Fl c
139option.
140.Pp
Damien Millere247cc42000-05-07 12:03:14 +1000141After a key is generated, instructions below detail where the keys
142should be placed to be activated.
143.Pp
Damien Miller32aa1441999-10-29 09:15:49 +1000144The options are as follows:
145.Bl -tag -width Ds
146.It Fl b Ar bits
Damien Miller450a7a12000-03-26 13:04:51 +1000147Specifies the number of bits in the key to create.
148Minimum is 512 bits.
149Generally 1024 bits is considered sufficient, and key sizes
150above that no longer improve security but make things slower.
151The default is 1024 bits.
Damien Miller32aa1441999-10-29 09:15:49 +1000152.It Fl c
153Requests changing the comment in the private and public key files.
Damien Millereb5fec62001-11-12 10:52:44 +1100154This operation is only supported for RSA1 keys.
Damien Miller32aa1441999-10-29 09:15:49 +1000155The program will prompt for the file containing the private keys, for
Ben Lindstromaafff9c2001-05-06 03:01:02 +0000156the passphrase if the key has one, and for the new comment.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000157.It Fl e
Ben Lindstrom46c264f2001-04-24 16:56:58 +0000158This option will read a private or public OpenSSH key file and
159print the key in a
Ben Lindstrom5a707822001-04-22 17:15:46 +0000160.Sq SECSH Public Key File Format
161to stdout.
162This option allows exporting keys for use by several commercial
163SSH implementations.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000164.It Fl f Ar filename
Damien Miller10f6f6b1999-11-17 17:29:08 +1100165Specifies the filename of the key file.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000166.It Fl i
167This option will read an unencrypted private (or public) key file
168in SSH2-compatible format and print an OpenSSH compatible private
169(or public) key to stdout.
170.Nm
Ben Lindstrom2857d9c2001-04-22 17:19:46 +0000171also reads the
Ben Lindstrom5a707822001-04-22 17:15:46 +0000172.Sq SECSH Public Key File Format .
173This option allows importing keys from several commercial
174SSH implementations.
Damien Miller10f6f6b1999-11-17 17:29:08 +1100175.It Fl l
Damien Millereb5fec62001-11-12 10:52:44 +1100176Show fingerprint of specified public key file.
177Private RSA1 keys are also supported.
178For RSA and DSA keys
179.Nm
180tries to find the matching public key file and prints its fingerprint.
Damien Miller32aa1441999-10-29 09:15:49 +1000181.It Fl p
182Requests changing the passphrase of a private key file instead of
Damien Miller450a7a12000-03-26 13:04:51 +1000183creating a new private key.
184The program will prompt for the file
Damien Miller32aa1441999-10-29 09:15:49 +1000185containing the private key, for the old passphrase, and twice for the
186new passphrase.
187.It Fl q
188Silence
189.Nm ssh-keygen .
190Used by
191.Pa /etc/rc
192when creating a new key.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000193.It Fl y
194This option will read a private
195OpenSSH format file and print an OpenSSH public key to stdout.
Damien Miller0bc1bd82000-11-13 22:57:25 +1100196.It Fl t Ar type
197Specifies the type of the key to create.
198The possible values are
199.Dq rsa1
200for protocol version 1 and
201.Dq rsa
202or
203.Dq dsa
204for protocol version 2.
205The default is
Ben Lindstromb7c92322001-03-05 05:10:52 +0000206.Dq rsa1 .
Ben Lindstrom8fd372b2001-03-12 03:02:17 +0000207.It Fl B
208Show the bubblebabble digest of specified private or public key file.
Damien Miller32aa1441999-10-29 09:15:49 +1000209.It Fl C Ar comment
210Provides the new comment.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000211.It Fl D Ar reader
212Download the RSA public key stored in the smartcard in
213.Ar reader .
Damien Miller32aa1441999-10-29 09:15:49 +1000214.It Fl N Ar new_passphrase
215Provides the new passphrase.
216.It Fl P Ar passphrase
217Provides the (old) passphrase.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000218.It Fl U Ar reader
219Upload an existing RSA private key into the smartcard in
220.Ar reader .
Damien Miller32aa1441999-10-29 09:15:49 +1000221.El
222.Sh FILES
223.Bl -tag -width Ds
Damien Miller32aa1441999-10-29 09:15:49 +1000224.It Pa $HOME/.ssh/identity
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000225Contains the protocol version 1 RSA authentication identity of the user.
Damien Miller450a7a12000-03-26 13:04:51 +1000226This file should not be readable by anyone but the user.
227It is possible to
Damien Miller32aa1441999-10-29 09:15:49 +1000228specify a passphrase when generating the key; that passphrase will be
Damien Miller450a7a12000-03-26 13:04:51 +1000229used to encrypt the private part of this file using 3DES.
230This file is not automatically accessed by
Damien Miller32aa1441999-10-29 09:15:49 +1000231.Nm
232but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000233.Xr ssh 1
Damien Millere247cc42000-05-07 12:03:14 +1000234will read this file when a login attempt is made.
Damien Miller32aa1441999-10-29 09:15:49 +1000235.It Pa $HOME/.ssh/identity.pub
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000236Contains the protocol version 1 RSA public key for authentication.
Damien Miller450a7a12000-03-26 13:04:51 +1000237The contents of this file should be added to
Damien Miller32aa1441999-10-29 09:15:49 +1000238.Pa $HOME/.ssh/authorized_keys
239on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000240where the user wishes to log in using RSA authentication.
Damien Miller450a7a12000-03-26 13:04:51 +1000241There is no need to keep the contents of this file secret.
Damien Millere247cc42000-05-07 12:03:14 +1000242.It Pa $HOME/.ssh/id_dsa
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000243Contains the protocol version 2 DSA authentication identity of the user.
Damien Millere247cc42000-05-07 12:03:14 +1000244This file should not be readable by anyone but the user.
245It is possible to
246specify a passphrase when generating the key; that passphrase will be
247used to encrypt the private part of this file using 3DES.
248This file is not automatically accessed by
249.Nm
250but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000251.Xr ssh 1
Damien Millere247cc42000-05-07 12:03:14 +1000252will read this file when a login attempt is made.
253.It Pa $HOME/.ssh/id_dsa.pub
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000254Contains the protocol version 2 DSA public key for authentication.
255The contents of this file should be added to
Ben Lindstromf96704d2001-06-25 04:17:12 +0000256.Pa $HOME/.ssh/authorized_keys
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000257on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000258where the user wishes to log in using public key authentication.
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000259There is no need to keep the contents of this file secret.
260.It Pa $HOME/.ssh/id_rsa
261Contains the protocol version 2 RSA authentication identity of the user.
262This file should not be readable by anyone but the user.
263It is possible to
264specify a passphrase when generating the key; that passphrase will be
265used to encrypt the private part of this file using 3DES.
266This file is not automatically accessed by
267.Nm
268but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000269.Xr ssh 1
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000270will read this file when a login attempt is made.
271.It Pa $HOME/.ssh/id_rsa.pub
272Contains the protocol version 2 RSA public key for authentication.
Damien Millere247cc42000-05-07 12:03:14 +1000273The contents of this file should be added to
Ben Lindstromf96704d2001-06-25 04:17:12 +0000274.Pa $HOME/.ssh/authorized_keys
Damien Millere247cc42000-05-07 12:03:14 +1000275on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000276where the user wishes to log in using public key authentication.
Damien Millere247cc42000-05-07 12:03:14 +1000277There is no need to keep the contents of this file secret.
Damien Miller37023962000-07-11 17:31:38 +1000278.El
Damien Miller0bc1bd82000-11-13 22:57:25 +1100279.Sh AUTHORS
Ben Lindstrom035782e2001-01-29 08:34:16 +0000280OpenSSH is a derivative of the original and free
281ssh 1.2.12 release by Tatu Ylonen.
282Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
283Theo de Raadt and Dug Song
284removed many bugs, re-added newer features and
285created OpenSSH.
286Markus Friedl contributed the support for SSH
287protocol versions 1.5 and 2.0.
Damien Miller32aa1441999-10-29 09:15:49 +1000288.Sh SEE ALSO
289.Xr ssh 1 ,
290.Xr ssh-add 1 ,
Damien Miller2e8b1c81999-11-15 23:33:56 +1100291.Xr ssh-agent 1 ,
Ben Lindstrom77788dc2001-02-10 23:10:33 +0000292.Xr sshd 8
Ben Lindstrom5a707822001-04-22 17:15:46 +0000293.Rs
Ben Lindstrom90fd0602001-06-25 04:45:33 +0000294.%A J. Galbraith
295.%A R. Thayer
Ben Lindstrom5a707822001-04-22 17:15:46 +0000296.%T "SECSH Public Key File Format"
297.%N draft-ietf-secsh-publickeyfile-01.txt
298.%D March 2001
299.%O work in progress material
300.Re