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Damien Miller55fafa02002-02-19 15:22:07 +11001.\" $OpenBSD: ssh-keygen.1,v 1.53 2002/02/16 14:53:37 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 Miller55fafa02002-02-19 15:22:07 +110050.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
Damien Millera41c8b12002-01-22 23:05:08 +110089can create RSA keys for use by SSH protocol version 1 and RSA or DSA
90keys for use by SSH protocol version 2. The type of key to be generated
91is specified with the
Damien Miller0bc1bd82000-11-13 22:57:25 +110092.Fl t
Damien Millera41c8b12002-01-22 23:05:08 +110093option.
Damien Millere247cc42000-05-07 12:03:14 +100094.Pp
Damien Miller32aa1441999-10-29 09:15:49 +100095Normally each user wishing to use SSH
Damien Millere247cc42000-05-07 12:03:14 +100096with RSA or DSA authentication runs this once to create the authentication
Damien Miller32aa1441999-10-29 09:15:49 +100097key in
Ben Lindstrom18a82ac2001-04-11 15:59:35 +000098.Pa $HOME/.ssh/identity ,
99.Pa $HOME/.ssh/id_dsa
Damien Millere247cc42000-05-07 12:03:14 +1000100or
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000101.Pa $HOME/.ssh/id_rsa .
Damien Millere247cc42000-05-07 12:03:14 +1000102Additionally, the system administrator may use this to generate host keys,
103as seen in
104.Pa /etc/rc .
Damien Miller32aa1441999-10-29 09:15:49 +1000105.Pp
106Normally this program generates the key and asks for a file in which
Damien Miller450a7a12000-03-26 13:04:51 +1000107to store the private key.
108The public key is stored in a file with the same name but
Damien Miller32aa1441999-10-29 09:15:49 +1000109.Dq .pub
Damien Miller450a7a12000-03-26 13:04:51 +1000110appended.
111The program also asks for a passphrase.
112The passphrase may be empty to indicate no passphrase
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000113(host keys must have an empty passphrase), or it may be a string of
Damien Miller450a7a12000-03-26 13:04:51 +1000114arbitrary length.
Ben Lindstrom4e366d52001-12-06 16:43:21 +0000115A passphrase is similar to a password, except it can be a phrase with a
116series of words, punctuation, numbers, whitespace, or any string of
117characters you want.
118Good passphrases are 10-30 characters long, are
Damien Miller32aa1441999-10-29 09:15:49 +1000119not simple sentences or otherwise easily guessable (English
Ben Lindstrom2a097a42001-06-09 01:13:40 +0000120prose has only 1-2 bits of entropy per character, and provides very bad
Ben Lindstrom4e366d52001-12-06 16:43:21 +0000121passphrases), and contain a mix of upper and lowercase letters,
122numbers, and non-alphanumeric characters.
Damien Miller450a7a12000-03-26 13:04:51 +1000123The passphrase can be changed later by using the
Damien Miller32aa1441999-10-29 09:15:49 +1000124.Fl p
125option.
126.Pp
Damien Miller450a7a12000-03-26 13:04:51 +1000127There is no way to recover a lost passphrase.
128If the passphrase is
Ben Lindstrom594e2032001-09-12 18:35:30 +0000129lost or forgotten, a new key must be generated and copied to the
Damien Miller32aa1441999-10-29 09:15:49 +1000130corresponding public key to other machines.
131.Pp
Ben Lindstrom5a707822001-04-22 17:15:46 +0000132For RSA1 keys,
133there is also a comment field in the key file that is only for
Damien Miller450a7a12000-03-26 13:04:51 +1000134convenience to the user to help identify the key.
135The comment can tell what the key is for, or whatever is useful.
136The comment is initialized to
Damien Miller32aa1441999-10-29 09:15:49 +1000137.Dq user@host
138when the key is created, but can be changed using the
139.Fl c
140option.
141.Pp
Damien Millere247cc42000-05-07 12:03:14 +1000142After a key is generated, instructions below detail where the keys
143should be placed to be activated.
144.Pp
Damien Miller32aa1441999-10-29 09:15:49 +1000145The options are as follows:
146.Bl -tag -width Ds
147.It Fl b Ar bits
Damien Miller450a7a12000-03-26 13:04:51 +1000148Specifies the number of bits in the key to create.
149Minimum is 512 bits.
150Generally 1024 bits is considered sufficient, and key sizes
151above that no longer improve security but make things slower.
152The default is 1024 bits.
Damien Miller32aa1441999-10-29 09:15:49 +1000153.It Fl c
154Requests changing the comment in the private and public key files.
Damien Millereb5fec62001-11-12 10:52:44 +1100155This operation is only supported for RSA1 keys.
Damien Miller32aa1441999-10-29 09:15:49 +1000156The program will prompt for the file containing the private keys, for
Ben Lindstromaafff9c2001-05-06 03:01:02 +0000157the passphrase if the key has one, and for the new comment.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000158.It Fl e
Ben Lindstrom46c264f2001-04-24 16:56:58 +0000159This option will read a private or public OpenSSH key file and
160print the key in a
Ben Lindstrom5a707822001-04-22 17:15:46 +0000161.Sq SECSH Public Key File Format
162to stdout.
163This option allows exporting keys for use by several commercial
164SSH implementations.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000165.It Fl f Ar filename
Damien Miller10f6f6b1999-11-17 17:29:08 +1100166Specifies the filename of the key file.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000167.It Fl i
168This option will read an unencrypted private (or public) key file
169in SSH2-compatible format and print an OpenSSH compatible private
170(or public) key to stdout.
171.Nm
Ben Lindstrom2857d9c2001-04-22 17:19:46 +0000172also reads the
Ben Lindstrom5a707822001-04-22 17:15:46 +0000173.Sq SECSH Public Key File Format .
174This option allows importing keys from several commercial
175SSH implementations.
Damien Miller10f6f6b1999-11-17 17:29:08 +1100176.It Fl l
Damien Millereb5fec62001-11-12 10:52:44 +1100177Show fingerprint of specified public key file.
178Private RSA1 keys are also supported.
179For RSA and DSA keys
180.Nm
181tries to find the matching public key file and prints its fingerprint.
Damien Miller32aa1441999-10-29 09:15:49 +1000182.It Fl p
183Requests changing the passphrase of a private key file instead of
Damien Miller450a7a12000-03-26 13:04:51 +1000184creating a new private key.
185The program will prompt for the file
Damien Miller32aa1441999-10-29 09:15:49 +1000186containing the private key, for the old passphrase, and twice for the
187new passphrase.
188.It Fl q
189Silence
190.Nm ssh-keygen .
191Used by
192.Pa /etc/rc
193when creating a new key.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000194.It Fl y
195This option will read a private
196OpenSSH format file and print an OpenSSH public key to stdout.
Damien Miller0bc1bd82000-11-13 22:57:25 +1100197.It Fl t Ar type
198Specifies the type of the key to create.
199The possible values are
200.Dq rsa1
201for protocol version 1 and
202.Dq rsa
203or
204.Dq dsa
205for protocol version 2.
Ben Lindstrom8fd372b2001-03-12 03:02:17 +0000206.It Fl B
207Show the bubblebabble digest of specified private or public key file.
Damien Miller32aa1441999-10-29 09:15:49 +1000208.It Fl C Ar comment
209Provides the new comment.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000210.It Fl D Ar reader
211Download the RSA public key stored in the smartcard in
212.Ar reader .
Damien Miller32aa1441999-10-29 09:15:49 +1000213.It Fl N Ar new_passphrase
214Provides the new passphrase.
215.It Fl P Ar passphrase
216Provides the (old) passphrase.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000217.It Fl U Ar reader
218Upload an existing RSA private key into the smartcard in
219.Ar reader .
Damien Miller32aa1441999-10-29 09:15:49 +1000220.El
221.Sh FILES
222.Bl -tag -width Ds
Damien Miller32aa1441999-10-29 09:15:49 +1000223.It Pa $HOME/.ssh/identity
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000224Contains the protocol version 1 RSA authentication identity of the user.
Damien Miller450a7a12000-03-26 13:04:51 +1000225This file should not be readable by anyone but the user.
226It is possible to
Damien Miller32aa1441999-10-29 09:15:49 +1000227specify a passphrase when generating the key; that passphrase will be
Damien Miller450a7a12000-03-26 13:04:51 +1000228used to encrypt the private part of this file using 3DES.
229This file is not automatically accessed by
Damien Miller32aa1441999-10-29 09:15:49 +1000230.Nm
231but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000232.Xr ssh 1
Damien Millere247cc42000-05-07 12:03:14 +1000233will read this file when a login attempt is made.
Damien Miller32aa1441999-10-29 09:15:49 +1000234.It Pa $HOME/.ssh/identity.pub
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000235Contains the protocol version 1 RSA public key for authentication.
Damien Miller450a7a12000-03-26 13:04:51 +1000236The contents of this file should be added to
Damien Miller32aa1441999-10-29 09:15:49 +1000237.Pa $HOME/.ssh/authorized_keys
238on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000239where the user wishes to log in using RSA authentication.
Damien Miller450a7a12000-03-26 13:04:51 +1000240There is no need to keep the contents of this file secret.
Damien Millere247cc42000-05-07 12:03:14 +1000241.It Pa $HOME/.ssh/id_dsa
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000242Contains the protocol version 2 DSA authentication identity of the user.
Damien Millere247cc42000-05-07 12:03:14 +1000243This file should not be readable by anyone but the user.
244It is possible to
245specify a passphrase when generating the key; that passphrase will be
246used to encrypt the private part of this file using 3DES.
247This file is not automatically accessed by
248.Nm
249but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000250.Xr ssh 1
Damien Millere247cc42000-05-07 12:03:14 +1000251will read this file when a login attempt is made.
252.It Pa $HOME/.ssh/id_dsa.pub
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000253Contains the protocol version 2 DSA public key for authentication.
254The contents of this file should be added to
Ben Lindstromf96704d2001-06-25 04:17:12 +0000255.Pa $HOME/.ssh/authorized_keys
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000256on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000257where the user wishes to log in using public key authentication.
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000258There is no need to keep the contents of this file secret.
259.It Pa $HOME/.ssh/id_rsa
260Contains the protocol version 2 RSA authentication identity of the user.
261This file should not be readable by anyone but the user.
262It is possible to
263specify a passphrase when generating the key; that passphrase will be
264used to encrypt the private part of this file using 3DES.
265This file is not automatically accessed by
266.Nm
267but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000268.Xr ssh 1
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000269will read this file when a login attempt is made.
270.It Pa $HOME/.ssh/id_rsa.pub
271Contains the protocol version 2 RSA public key for authentication.
Damien Millere247cc42000-05-07 12:03:14 +1000272The contents of this file should be added to
Ben Lindstromf96704d2001-06-25 04:17:12 +0000273.Pa $HOME/.ssh/authorized_keys
Damien Millere247cc42000-05-07 12:03:14 +1000274on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000275where the user wishes to log in using public key authentication.
Damien Millere247cc42000-05-07 12:03:14 +1000276There is no need to keep the contents of this file secret.
Damien Miller37023962000-07-11 17:31:38 +1000277.El
Damien Miller0bc1bd82000-11-13 22:57:25 +1100278.Sh AUTHORS
Ben Lindstrom035782e2001-01-29 08:34:16 +0000279OpenSSH is a derivative of the original and free
280ssh 1.2.12 release by Tatu Ylonen.
281Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
282Theo de Raadt and Dug Song
283removed many bugs, re-added newer features and
284created OpenSSH.
285Markus Friedl contributed the support for SSH
286protocol versions 1.5 and 2.0.
Damien Miller32aa1441999-10-29 09:15:49 +1000287.Sh SEE ALSO
288.Xr ssh 1 ,
289.Xr ssh-add 1 ,
Damien Miller2e8b1c81999-11-15 23:33:56 +1100290.Xr ssh-agent 1 ,
Ben Lindstrom77788dc2001-02-10 23:10:33 +0000291.Xr sshd 8
Ben Lindstrom5a707822001-04-22 17:15:46 +0000292.Rs
Ben Lindstrom90fd0602001-06-25 04:45:33 +0000293.%A J. Galbraith
294.%A R. Thayer
Ben Lindstrom5a707822001-04-22 17:15:46 +0000295.%T "SECSH Public Key File Format"
296.%N draft-ietf-secsh-publickeyfile-01.txt
297.%D March 2001
298.%O work in progress material
299.Re