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Damien Millerfbf486b2003-05-23 18:44:23 +10001.\" $OpenBSD: ssh-keygen.1,v 1.58 2003/05/20 12:09:31 jmc 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 Miller495dca32003-04-01 21:42:14 +100048.Bk -words
Damien Miller0bc1bd82000-11-13 22:57:25 +110049.Op Fl q
Damien Miller32aa1441999-10-29 09:15:49 +100050.Op Fl b Ar bits
Damien Miller55fafa02002-02-19 15:22:07 +110051.Fl t Ar type
Damien Miller32aa1441999-10-29 09:15:49 +100052.Op Fl N Ar new_passphrase
53.Op Fl C Ar comment
Damien Miller1a425f32000-09-02 10:08:09 +110054.Op Fl f Ar output_keyfile
Damien Miller495dca32003-04-01 21:42:14 +100055.Ek
Damien Miller32aa1441999-10-29 09:15:49 +100056.Nm ssh-keygen
57.Fl p
58.Op Fl P Ar old_passphrase
59.Op Fl N Ar new_passphrase
Damien Miller10f6f6b1999-11-17 17:29:08 +110060.Op Fl f Ar keyfile
Damien Miller32aa1441999-10-29 09:15:49 +100061.Nm ssh-keygen
Ben Lindstrom5a707822001-04-22 17:15:46 +000062.Fl i
Damien Miller1a425f32000-09-02 10:08:09 +110063.Op Fl f Ar input_keyfile
Damien Millere247cc42000-05-07 12:03:14 +100064.Nm ssh-keygen
Ben Lindstrom5a707822001-04-22 17:15:46 +000065.Fl e
Damien Miller1a425f32000-09-02 10:08:09 +110066.Op Fl f Ar input_keyfile
Damien Millere247cc42000-05-07 12:03:14 +100067.Nm ssh-keygen
68.Fl y
Damien Miller1a425f32000-09-02 10:08:09 +110069.Op Fl f Ar input_keyfile
Damien Millere247cc42000-05-07 12:03:14 +100070.Nm ssh-keygen
Damien Miller32aa1441999-10-29 09:15:49 +100071.Fl c
72.Op Fl P Ar passphrase
73.Op Fl C Ar comment
Damien Miller10f6f6b1999-11-17 17:29:08 +110074.Op Fl f Ar keyfile
75.Nm ssh-keygen
76.Fl l
Ben Lindstrom8fd372b2001-03-12 03:02:17 +000077.Op Fl f Ar input_keyfile
78.Nm ssh-keygen
79.Fl B
Damien Miller1a425f32000-09-02 10:08:09 +110080.Op Fl f Ar input_keyfile
Ben Lindstroma1ec4a92001-08-06 21:51:34 +000081.Nm ssh-keygen
82.Fl D Ar reader
83.Nm ssh-keygen
84.Fl U Ar reader
85.Op Fl f Ar input_keyfile
Damien Miller37876e92003-05-15 10:19:46 +100086.Nm ssh-keygen
87.Fl r Ar hostname
88.Op Fl f Ar input_keyfile
89.Op Fl g
Damien Miller22c77262000-04-13 12:26:34 +100090.Sh DESCRIPTION
Damien Miller32aa1441999-10-29 09:15:49 +100091.Nm
Ben Lindstrom5a707822001-04-22 17:15:46 +000092generates, manages and converts authentication keys for
Damien Miller32aa1441999-10-29 09:15:49 +100093.Xr ssh 1 .
Damien Millere247cc42000-05-07 12:03:14 +100094.Nm
Ben Lindstromcb72e4f2002-06-21 00:41:51 +000095can create RSA keys for use by SSH protocol version 1 and RSA or DSA
Damien Millerfbf486b2003-05-23 18:44:23 +100096keys for use by SSH protocol version 2.
97The type of key to be generated is specified with the
Damien Miller0bc1bd82000-11-13 22:57:25 +110098.Fl t
Damien Millera41c8b12002-01-22 23:05:08 +110099option.
Damien Millere247cc42000-05-07 12:03:14 +1000100.Pp
Damien Miller32aa1441999-10-29 09:15:49 +1000101Normally each user wishing to use SSH
Damien Millere247cc42000-05-07 12:03:14 +1000102with RSA or DSA authentication runs this once to create the authentication
Damien Miller32aa1441999-10-29 09:15:49 +1000103key in
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000104.Pa $HOME/.ssh/identity ,
105.Pa $HOME/.ssh/id_dsa
Damien Millere247cc42000-05-07 12:03:14 +1000106or
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000107.Pa $HOME/.ssh/id_rsa .
Damien Millere247cc42000-05-07 12:03:14 +1000108Additionally, the system administrator may use this to generate host keys,
109as seen in
110.Pa /etc/rc .
Damien Miller32aa1441999-10-29 09:15:49 +1000111.Pp
112Normally this program generates the key and asks for a file in which
Damien Miller450a7a12000-03-26 13:04:51 +1000113to store the private key.
114The public key is stored in a file with the same name but
Damien Miller32aa1441999-10-29 09:15:49 +1000115.Dq .pub
Damien Miller450a7a12000-03-26 13:04:51 +1000116appended.
117The program also asks for a passphrase.
118The passphrase may be empty to indicate no passphrase
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000119(host keys must have an empty passphrase), or it may be a string of
Damien Miller450a7a12000-03-26 13:04:51 +1000120arbitrary length.
Ben Lindstrom4e366d52001-12-06 16:43:21 +0000121A passphrase is similar to a password, except it can be a phrase with a
122series of words, punctuation, numbers, whitespace, or any string of
123characters you want.
124Good passphrases are 10-30 characters long, are
Damien Miller32aa1441999-10-29 09:15:49 +1000125not simple sentences or otherwise easily guessable (English
Ben Lindstrom2a097a42001-06-09 01:13:40 +0000126prose has only 1-2 bits of entropy per character, and provides very bad
Ben Lindstrom4e366d52001-12-06 16:43:21 +0000127passphrases), and contain a mix of upper and lowercase letters,
128numbers, and non-alphanumeric characters.
Damien Miller450a7a12000-03-26 13:04:51 +1000129The passphrase can be changed later by using the
Damien Miller32aa1441999-10-29 09:15:49 +1000130.Fl p
131option.
132.Pp
Damien Miller450a7a12000-03-26 13:04:51 +1000133There is no way to recover a lost passphrase.
134If the passphrase is
Ben Lindstrom594e2032001-09-12 18:35:30 +0000135lost or forgotten, a new key must be generated and copied to the
Damien Miller32aa1441999-10-29 09:15:49 +1000136corresponding public key to other machines.
137.Pp
Ben Lindstrom5a707822001-04-22 17:15:46 +0000138For RSA1 keys,
139there is also a comment field in the key file that is only for
Damien Miller450a7a12000-03-26 13:04:51 +1000140convenience to the user to help identify the key.
141The comment can tell what the key is for, or whatever is useful.
142The comment is initialized to
Damien Miller32aa1441999-10-29 09:15:49 +1000143.Dq user@host
144when the key is created, but can be changed using the
145.Fl c
146option.
147.Pp
Damien Millere247cc42000-05-07 12:03:14 +1000148After a key is generated, instructions below detail where the keys
149should be placed to be activated.
150.Pp
Damien Miller32aa1441999-10-29 09:15:49 +1000151The options are as follows:
152.Bl -tag -width Ds
153.It Fl b Ar bits
Damien Miller450a7a12000-03-26 13:04:51 +1000154Specifies the number of bits in the key to create.
155Minimum is 512 bits.
Ben Lindstrom9394d2f2002-12-23 02:11:54 +0000156Generally, 1024 bits is considered sufficient.
Damien Miller450a7a12000-03-26 13:04:51 +1000157The default is 1024 bits.
Damien Miller32aa1441999-10-29 09:15:49 +1000158.It Fl c
159Requests changing the comment in the private and public key files.
Damien Millereb5fec62001-11-12 10:52:44 +1100160This operation is only supported for RSA1 keys.
Damien Miller32aa1441999-10-29 09:15:49 +1000161The program will prompt for the file containing the private keys, for
Ben Lindstromaafff9c2001-05-06 03:01:02 +0000162the passphrase if the key has one, and for the new comment.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000163.It Fl e
Ben Lindstrom46c264f2001-04-24 16:56:58 +0000164This option will read a private or public OpenSSH key file and
165print the key in a
Ben Lindstrom5a707822001-04-22 17:15:46 +0000166.Sq SECSH Public Key File Format
167to stdout.
168This option allows exporting keys for use by several commercial
169SSH implementations.
Damien Miller37876e92003-05-15 10:19:46 +1000170.It Fl g
171Use generic DNS resource record format.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000172.It Fl f Ar filename
Damien Miller10f6f6b1999-11-17 17:29:08 +1100173Specifies the filename of the key file.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000174.It Fl i
175This option will read an unencrypted private (or public) key file
176in SSH2-compatible format and print an OpenSSH compatible private
177(or public) key to stdout.
178.Nm
Ben Lindstrom2857d9c2001-04-22 17:19:46 +0000179also reads the
Ben Lindstrom5a707822001-04-22 17:15:46 +0000180.Sq SECSH Public Key File Format .
181This option allows importing keys from several commercial
182SSH implementations.
Damien Miller10f6f6b1999-11-17 17:29:08 +1100183.It Fl l
Damien Millereb5fec62001-11-12 10:52:44 +1100184Show fingerprint of specified public key file.
185Private RSA1 keys are also supported.
186For RSA and DSA keys
187.Nm
188tries to find the matching public key file and prints its fingerprint.
Damien Miller32aa1441999-10-29 09:15:49 +1000189.It Fl p
190Requests changing the passphrase of a private key file instead of
Damien Miller450a7a12000-03-26 13:04:51 +1000191creating a new private key.
192The program will prompt for the file
Damien Miller32aa1441999-10-29 09:15:49 +1000193containing the private key, for the old passphrase, and twice for the
194new passphrase.
195.It Fl q
196Silence
197.Nm ssh-keygen .
198Used by
199.Pa /etc/rc
200when creating a new key.
Ben Lindstrom5a707822001-04-22 17:15:46 +0000201.It Fl y
202This option will read a private
203OpenSSH format file and print an OpenSSH public key to stdout.
Damien Miller0bc1bd82000-11-13 22:57:25 +1100204.It Fl t Ar type
205Specifies the type of the key to create.
206The possible values are
207.Dq rsa1
208for protocol version 1 and
209.Dq rsa
210or
211.Dq dsa
212for protocol version 2.
Ben Lindstrom8fd372b2001-03-12 03:02:17 +0000213.It Fl B
214Show the bubblebabble digest of specified private or public key file.
Damien Miller32aa1441999-10-29 09:15:49 +1000215.It Fl C Ar comment
216Provides the new comment.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000217.It Fl D Ar reader
218Download the RSA public key stored in the smartcard in
219.Ar reader .
Damien Miller32aa1441999-10-29 09:15:49 +1000220.It Fl N Ar new_passphrase
221Provides the new passphrase.
222.It Fl P Ar passphrase
223Provides the (old) passphrase.
Ben Lindstroma1ec4a92001-08-06 21:51:34 +0000224.It Fl U Ar reader
225Upload an existing RSA private key into the smartcard in
226.Ar reader .
Damien Miller37876e92003-05-15 10:19:46 +1000227.It Fl r Ar hostname
228Print DNS resource record with the specified
229.Ar hostname .
Damien Miller32aa1441999-10-29 09:15:49 +1000230.El
231.Sh FILES
232.Bl -tag -width Ds
Damien Miller32aa1441999-10-29 09:15:49 +1000233.It Pa $HOME/.ssh/identity
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000234Contains the protocol version 1 RSA authentication identity of the user.
Damien Miller450a7a12000-03-26 13:04:51 +1000235This file should not be readable by anyone but the user.
236It is possible to
Damien Miller32aa1441999-10-29 09:15:49 +1000237specify a passphrase when generating the key; that passphrase will be
Damien Miller450a7a12000-03-26 13:04:51 +1000238used to encrypt the private part of this file using 3DES.
239This file is not automatically accessed by
Damien Miller32aa1441999-10-29 09:15:49 +1000240.Nm
241but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000242.Xr ssh 1
Damien Millere247cc42000-05-07 12:03:14 +1000243will read this file when a login attempt is made.
Damien Miller32aa1441999-10-29 09:15:49 +1000244.It Pa $HOME/.ssh/identity.pub
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000245Contains the protocol version 1 RSA public key for authentication.
Damien Miller450a7a12000-03-26 13:04:51 +1000246The contents of this file should be added to
Damien Miller32aa1441999-10-29 09:15:49 +1000247.Pa $HOME/.ssh/authorized_keys
248on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000249where the user wishes to log in using RSA authentication.
Damien Miller450a7a12000-03-26 13:04:51 +1000250There is no need to keep the contents of this file secret.
Damien Millere247cc42000-05-07 12:03:14 +1000251.It Pa $HOME/.ssh/id_dsa
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000252Contains the protocol version 2 DSA authentication identity of the user.
Damien Millere247cc42000-05-07 12:03:14 +1000253This file should not be readable by anyone but the user.
254It is possible to
255specify a passphrase when generating the key; that passphrase will be
256used to encrypt the private part of this file using 3DES.
257This file is not automatically accessed by
258.Nm
259but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000260.Xr ssh 1
Damien Millere247cc42000-05-07 12:03:14 +1000261will read this file when a login attempt is made.
262.It Pa $HOME/.ssh/id_dsa.pub
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000263Contains the protocol version 2 DSA public key for authentication.
264The contents of this file should be added to
Ben Lindstromf96704d2001-06-25 04:17:12 +0000265.Pa $HOME/.ssh/authorized_keys
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000266on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000267where the user wishes to log in using public key authentication.
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000268There is no need to keep the contents of this file secret.
269.It Pa $HOME/.ssh/id_rsa
270Contains the protocol version 2 RSA authentication identity of the user.
271This file should not be readable by anyone but the user.
272It is possible to
273specify a passphrase when generating the key; that passphrase will be
274used to encrypt the private part of this file using 3DES.
275This file is not automatically accessed by
276.Nm
277but it is offered as the default file for the private key.
Ben Lindstrombda98b02001-07-04 03:35:24 +0000278.Xr ssh 1
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000279will read this file when a login attempt is made.
280.It Pa $HOME/.ssh/id_rsa.pub
281Contains the protocol version 2 RSA public key for authentication.
Damien Millere247cc42000-05-07 12:03:14 +1000282The contents of this file should be added to
Ben Lindstromf96704d2001-06-25 04:17:12 +0000283.Pa $HOME/.ssh/authorized_keys
Damien Millere247cc42000-05-07 12:03:14 +1000284on all machines
Ben Lindstrom594e2032001-09-12 18:35:30 +0000285where the user wishes to log in using public key authentication.
Damien Millere247cc42000-05-07 12:03:14 +1000286There is no need to keep the contents of this file secret.
Damien Miller37023962000-07-11 17:31:38 +1000287.El
Damien Miller0bc1bd82000-11-13 22:57:25 +1100288.Sh AUTHORS
Ben Lindstrom035782e2001-01-29 08:34:16 +0000289OpenSSH is a derivative of the original and free
290ssh 1.2.12 release by Tatu Ylonen.
291Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
292Theo de Raadt and Dug Song
293removed many bugs, re-added newer features and
294created OpenSSH.
295Markus Friedl contributed the support for SSH
296protocol versions 1.5 and 2.0.
Damien Miller32aa1441999-10-29 09:15:49 +1000297.Sh SEE ALSO
298.Xr ssh 1 ,
299.Xr ssh-add 1 ,
Damien Miller2e8b1c81999-11-15 23:33:56 +1100300.Xr ssh-agent 1 ,
Ben Lindstrom77788dc2001-02-10 23:10:33 +0000301.Xr sshd 8
Ben Lindstrom5a707822001-04-22 17:15:46 +0000302.Rs
Ben Lindstrom90fd0602001-06-25 04:45:33 +0000303.%A J. Galbraith
304.%A R. Thayer
Ben Lindstrom5a707822001-04-22 17:15:46 +0000305.%T "SECSH Public Key File Format"
306.%N draft-ietf-secsh-publickeyfile-01.txt
307.%D March 2001
308.%O work in progress material
309.Re