1 .\" $OpenBSD: ssh-keygen.1,v 1.39 2001/04/22 23:58:36 markus Exp $
5 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
6 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 .\" All rights reserved
9 .\" 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".
16 .\" 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.
20 .\" Redistribution and use in source and binary forms, with or without
21 .\" modification, are permitted provided that the following conditions
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.
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.
40 .Dd September 25, 1999
45 .Nd authentication key generation, management and conversion
51 .Op Fl N Ar new_passphrase
53 .Op Fl f Ar output_keyfile
56 .Op Fl P Ar old_passphrase
57 .Op Fl N Ar new_passphrase
61 .Op Fl f Ar input_keyfile
64 .Op Fl f Ar input_keyfile
67 .Op Fl f Ar input_keyfile
70 .Op Fl P Ar passphrase
75 .Op Fl f Ar input_keyfile
78 .Op Fl f Ar input_keyfile
81 generates, manages and converts authentication keys for
84 defaults to generating a RSA1 key for use by SSH protocol version 1.
87 option allows you to create a key for use by SSH protocol version 2.
89 Normally each user wishing to use SSH
90 with RSA or DSA authentication runs this once to create the authentication
92 .Pa $HOME/.ssh/identity ,
95 .Pa $HOME/.ssh/id_rsa .
96 Additionally, the system administrator may use this to generate host keys,
100 Normally this program generates the key and asks for a file in which
101 to store the private key.
102 The public key is stored in a file with the same name but
105 The program also asks for a passphrase.
106 The passphrase may be empty to indicate no passphrase
107 (host keys must have an empty passphrase), or it may be a string of
109 Good passphrases are 10-30 characters long and are
110 not simple sentences or otherwise easily guessable (English
111 prose has only 1-2 bits of entropy per word, and provides very bad
113 The passphrase can be changed later by using the
117 There is no way to recover a lost passphrase.
119 lost or forgotten, you will have to generate a new key and copy the
120 corresponding public key to other machines.
123 there is also a comment field in the key file that is only for
124 convenience to the user to help identify the key.
125 The comment can tell what the key is for, or whatever is useful.
126 The comment is initialized to
128 when the key is created, but can be changed using the
132 After a key is generated, instructions below detail where the keys
133 should be placed to be activated.
135 The options are as follows:
138 Specifies the number of bits in the key to create.
140 Generally 1024 bits is considered sufficient, and key sizes
141 above that no longer improve security but make things slower.
142 The default is 1024 bits.
144 Requests changing the comment in the private and public key files.
145 The program will prompt for the file containing the private keys, for
146 passphrase if the key has one, and for the new comment.
148 This option will read a private OpenSSH key file and print the key in a
149 .Sq SECSH Public Key File Format
151 This option allows exporting keys for use by several commercial
154 Specifies the filename of the key file.
156 This option will read an unencrypted private (or public) key file
157 in SSH2-compatible format and print an OpenSSH compatible private
158 (or public) key to stdout.
161 .Sq SECSH Public Key File Format .
162 This option allows importing keys from several commercial
165 Show fingerprint of specified private or public key file.
167 Requests changing the passphrase of a private key file instead of
168 creating a new private key.
169 The program will prompt for the file
170 containing the private key, for the old passphrase, and twice for the
177 when creating a new key.
179 This option will read a private
180 OpenSSH format file and print an OpenSSH public key to stdout.
182 Specifies the type of the key to create.
183 The possible values are
185 for protocol version 1 and
189 for protocol version 2.
193 Show the bubblebabble digest of specified private or public key file.
195 Provides the new comment.
196 .It Fl N Ar new_passphrase
197 Provides the new passphrase.
198 .It Fl P Ar passphrase
199 Provides the (old) passphrase.
203 .It Pa $HOME/.ssh/identity
204 Contains the protocol version 1 RSA authentication identity of the user.
205 This file should not be readable by anyone but the user.
207 specify a passphrase when generating the key; that passphrase will be
208 used to encrypt the private part of this file using 3DES.
209 This file is not automatically accessed by
211 but it is offered as the default file for the private key.
213 will read this file when a login attempt is made.
214 .It Pa $HOME/.ssh/identity.pub
215 Contains the protocol version 1 RSA public key for authentication.
216 The contents of this file should be added to
217 .Pa $HOME/.ssh/authorized_keys
219 where you wish to log in using RSA authentication.
220 There is no need to keep the contents of this file secret.
221 .It Pa $HOME/.ssh/id_dsa
222 Contains the protocol version 2 DSA authentication identity of the user.
223 This file should not be readable by anyone but the user.
225 specify a passphrase when generating the key; that passphrase will be
226 used to encrypt the private part of this file using 3DES.
227 This file is not automatically accessed by
229 but it is offered as the default file for the private key.
231 will read this file when a login attempt is made.
232 .It Pa $HOME/.ssh/id_dsa.pub
233 Contains the protocol version 2 DSA public key for authentication.
234 The contents of this file should be added to
235 .Pa $HOME/.ssh/authorized_keys2
237 where you wish to log in using public key authentication.
238 There is no need to keep the contents of this file secret.
239 .It Pa $HOME/.ssh/id_rsa
240 Contains the protocol version 2 RSA authentication identity of the user.
241 This file should not be readable by anyone but the user.
243 specify a passphrase when generating the key; that passphrase will be
244 used to encrypt the private part of this file using 3DES.
245 This file is not automatically accessed by
247 but it is offered as the default file for the private key.
249 will read this file when a login attempt is made.
250 .It Pa $HOME/.ssh/id_rsa.pub
251 Contains the protocol version 2 RSA public key for authentication.
252 The contents of this file should be added to
253 .Pa $HOME/.ssh/authorized_keys2
255 where you wish to log in using public key authentication.
256 There is no need to keep the contents of this file secret.
259 OpenSSH is a derivative of the original and free
260 ssh 1.2.12 release by Tatu Ylonen.
261 Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
262 Theo de Raadt and Dug Song
263 removed many bugs, re-added newer features and
265 Markus Friedl contributed the support for SSH
266 protocol versions 1.5 and 2.0.
275 .%T "SECSH Public Key File Format"
276 .%N draft-ietf-secsh-publickeyfile-01.txt
278 .%O work in progress material