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e9a17296 | 1 | .\" $OpenBSD: ssh-keygen.1,v 1.53 2002/02/16 14:53:37 stevesk Exp $ |
3c0ef626 | 2 | .\" |
3 | .\" -*- nroff -*- | |
4 | .\" | |
5 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
7 | .\" All rights reserved | |
8 | .\" | |
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". | |
14 | .\" | |
15 | .\" | |
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. | |
19 | .\" | |
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. | |
39 | .\" | |
40 | .Dd September 25, 1999 | |
41 | .Dt SSH-KEYGEN 1 | |
42 | .Os | |
43 | .Sh NAME | |
44 | .Nm ssh-keygen | |
45 | .Nd authentication key generation, management and conversion | |
46 | .Sh SYNOPSIS | |
47 | .Nm ssh-keygen | |
48 | .Op Fl q | |
49 | .Op Fl b Ar bits | |
e9a17296 | 50 | .Fl t Ar type |
3c0ef626 | 51 | .Op Fl N Ar new_passphrase |
52 | .Op Fl C Ar comment | |
53 | .Op Fl f Ar output_keyfile | |
54 | .Nm ssh-keygen | |
55 | .Fl p | |
56 | .Op Fl P Ar old_passphrase | |
57 | .Op Fl N Ar new_passphrase | |
58 | .Op Fl f Ar keyfile | |
59 | .Nm ssh-keygen | |
60 | .Fl i | |
61 | .Op Fl f Ar input_keyfile | |
62 | .Nm ssh-keygen | |
63 | .Fl e | |
64 | .Op Fl f Ar input_keyfile | |
65 | .Nm ssh-keygen | |
66 | .Fl y | |
67 | .Op Fl f Ar input_keyfile | |
68 | .Nm ssh-keygen | |
69 | .Fl c | |
70 | .Op Fl P Ar passphrase | |
71 | .Op Fl C Ar comment | |
72 | .Op Fl f Ar keyfile | |
73 | .Nm ssh-keygen | |
74 | .Fl l | |
75 | .Op Fl f Ar input_keyfile | |
76 | .Nm ssh-keygen | |
77 | .Fl B | |
78 | .Op Fl f Ar input_keyfile | |
79 | .Nm ssh-keygen | |
80 | .Fl D Ar reader | |
81 | .Nm ssh-keygen | |
82 | .Fl U Ar reader | |
83 | .Op Fl f Ar input_keyfile | |
84 | .Sh DESCRIPTION | |
85 | .Nm | |
86 | generates, manages and converts authentication keys for | |
87 | .Xr ssh 1 . | |
88 | .Nm | |
e9a17296 | 89 | can create RSA keys for use by SSH protocol version 1 and RSA or DSA |
90 | keys for use by SSH protocol version 2. The type of key to be generated | |
91 | is specified with the | |
3c0ef626 | 92 | .Fl t |
e9a17296 | 93 | option. |
3c0ef626 | 94 | .Pp |
95 | Normally each user wishing to use SSH | |
96 | with RSA or DSA authentication runs this once to create the authentication | |
97 | key in | |
98 | .Pa $HOME/.ssh/identity , | |
99 | .Pa $HOME/.ssh/id_dsa | |
100 | or | |
101 | .Pa $HOME/.ssh/id_rsa . | |
102 | Additionally, the system administrator may use this to generate host keys, | |
103 | as seen in | |
104 | .Pa /etc/rc . | |
105 | .Pp | |
106 | Normally this program generates the key and asks for a file in which | |
107 | to store the private key. | |
108 | The public key is stored in a file with the same name but | |
109 | .Dq .pub | |
110 | appended. | |
111 | The program also asks for a passphrase. | |
112 | The passphrase may be empty to indicate no passphrase | |
113 | (host keys must have an empty passphrase), or it may be a string of | |
114 | arbitrary length. | |
e9a17296 | 115 | A passphrase is similar to a password, except it can be a phrase with a |
116 | series of words, punctuation, numbers, whitespace, or any string of | |
117 | characters you want. | |
118 | Good passphrases are 10-30 characters long, are | |
3c0ef626 | 119 | not simple sentences or otherwise easily guessable (English |
120 | prose has only 1-2 bits of entropy per character, and provides very bad | |
e9a17296 | 121 | passphrases), and contain a mix of upper and lowercase letters, |
122 | numbers, and non-alphanumeric characters. | |
3c0ef626 | 123 | The passphrase can be changed later by using the |
124 | .Fl p | |
125 | option. | |
126 | .Pp | |
127 | There is no way to recover a lost passphrase. | |
128 | If the passphrase is | |
129 | lost or forgotten, a new key must be generated and copied to the | |
130 | corresponding public key to other machines. | |
131 | .Pp | |
132 | For RSA1 keys, | |
133 | there is also a comment field in the key file that is only for | |
134 | convenience to the user to help identify the key. | |
135 | The comment can tell what the key is for, or whatever is useful. | |
136 | The comment is initialized to | |
137 | .Dq user@host | |
138 | when the key is created, but can be changed using the | |
139 | .Fl c | |
140 | option. | |
141 | .Pp | |
142 | After a key is generated, instructions below detail where the keys | |
143 | should be placed to be activated. | |
144 | .Pp | |
145 | The options are as follows: | |
146 | .Bl -tag -width Ds | |
147 | .It Fl b Ar bits | |
148 | Specifies the number of bits in the key to create. | |
149 | Minimum is 512 bits. | |
150 | Generally 1024 bits is considered sufficient, and key sizes | |
151 | above that no longer improve security but make things slower. | |
152 | The default is 1024 bits. | |
153 | .It Fl c | |
154 | Requests changing the comment in the private and public key files. | |
155 | This operation is only supported for RSA1 keys. | |
156 | The program will prompt for the file containing the private keys, for | |
157 | the passphrase if the key has one, and for the new comment. | |
158 | .It Fl e | |
159 | This option will read a private or public OpenSSH key file and | |
160 | print the key in a | |
161 | .Sq SECSH Public Key File Format | |
162 | to stdout. | |
163 | This option allows exporting keys for use by several commercial | |
164 | SSH implementations. | |
165 | .It Fl f Ar filename | |
166 | Specifies the filename of the key file. | |
167 | .It Fl i | |
168 | This option will read an unencrypted private (or public) key file | |
169 | in SSH2-compatible format and print an OpenSSH compatible private | |
170 | (or public) key to stdout. | |
171 | .Nm | |
172 | also reads the | |
173 | .Sq SECSH Public Key File Format . | |
174 | This option allows importing keys from several commercial | |
175 | SSH implementations. | |
176 | .It Fl l | |
177 | Show fingerprint of specified public key file. | |
178 | Private RSA1 keys are also supported. | |
179 | For RSA and DSA keys | |
180 | .Nm | |
181 | tries to find the matching public key file and prints its fingerprint. | |
182 | .It Fl p | |
183 | Requests changing the passphrase of a private key file instead of | |
184 | creating a new private key. | |
185 | The program will prompt for the file | |
186 | containing the private key, for the old passphrase, and twice for the | |
187 | new passphrase. | |
188 | .It Fl q | |
189 | Silence | |
190 | .Nm ssh-keygen . | |
191 | Used by | |
192 | .Pa /etc/rc | |
193 | when creating a new key. | |
194 | .It Fl y | |
195 | This option will read a private | |
196 | OpenSSH format file and print an OpenSSH public key to stdout. | |
197 | .It Fl t Ar type | |
198 | Specifies the type of the key to create. | |
199 | The possible values are | |
200 | .Dq rsa1 | |
201 | for protocol version 1 and | |
202 | .Dq rsa | |
203 | or | |
204 | .Dq dsa | |
205 | for protocol version 2. | |
3c0ef626 | 206 | .It Fl B |
207 | Show the bubblebabble digest of specified private or public key file. | |
208 | .It Fl C Ar comment | |
209 | Provides the new comment. | |
210 | .It Fl D Ar reader | |
211 | Download the RSA public key stored in the smartcard in | |
212 | .Ar reader . | |
213 | .It Fl N Ar new_passphrase | |
214 | Provides the new passphrase. | |
215 | .It Fl P Ar passphrase | |
216 | Provides the (old) passphrase. | |
217 | .It Fl U Ar reader | |
218 | Upload an existing RSA private key into the smartcard in | |
219 | .Ar reader . | |
220 | .El | |
221 | .Sh FILES | |
222 | .Bl -tag -width Ds | |
223 | .It Pa $HOME/.ssh/identity | |
224 | Contains the protocol version 1 RSA authentication identity of the user. | |
225 | This file should not be readable by anyone but the user. | |
226 | It is possible to | |
227 | specify a passphrase when generating the key; that passphrase will be | |
228 | used to encrypt the private part of this file using 3DES. | |
229 | This file is not automatically accessed by | |
230 | .Nm | |
231 | but it is offered as the default file for the private key. | |
232 | .Xr ssh 1 | |
233 | will read this file when a login attempt is made. | |
234 | .It Pa $HOME/.ssh/identity.pub | |
235 | Contains the protocol version 1 RSA public key for authentication. | |
236 | The contents of this file should be added to | |
237 | .Pa $HOME/.ssh/authorized_keys | |
238 | on all machines | |
239 | where the user wishes to log in using RSA authentication. | |
240 | There is no need to keep the contents of this file secret. | |
241 | .It Pa $HOME/.ssh/id_dsa | |
242 | Contains the protocol version 2 DSA authentication identity of the user. | |
243 | This file should not be readable by anyone but the user. | |
244 | It is possible to | |
245 | specify a passphrase when generating the key; that passphrase will be | |
246 | used to encrypt the private part of this file using 3DES. | |
247 | This file is not automatically accessed by | |
248 | .Nm | |
249 | but it is offered as the default file for the private key. | |
250 | .Xr ssh 1 | |
251 | will read this file when a login attempt is made. | |
252 | .It Pa $HOME/.ssh/id_dsa.pub | |
253 | Contains the protocol version 2 DSA public key for authentication. | |
254 | The contents of this file should be added to | |
255 | .Pa $HOME/.ssh/authorized_keys | |
256 | on all machines | |
257 | where the user wishes to log in using public key authentication. | |
258 | There is no need to keep the contents of this file secret. | |
259 | .It Pa $HOME/.ssh/id_rsa | |
260 | Contains the protocol version 2 RSA authentication identity of the user. | |
261 | This file should not be readable by anyone but the user. | |
262 | It is possible to | |
263 | specify a passphrase when generating the key; that passphrase will be | |
264 | used to encrypt the private part of this file using 3DES. | |
265 | This file is not automatically accessed by | |
266 | .Nm | |
267 | but it is offered as the default file for the private key. | |
268 | .Xr ssh 1 | |
269 | will read this file when a login attempt is made. | |
270 | .It Pa $HOME/.ssh/id_rsa.pub | |
271 | Contains the protocol version 2 RSA public key for authentication. | |
272 | The contents of this file should be added to | |
273 | .Pa $HOME/.ssh/authorized_keys | |
274 | on all machines | |
275 | where the user wishes to log in using public key authentication. | |
276 | There is no need to keep the contents of this file secret. | |
277 | .El | |
278 | .Sh AUTHORS | |
279 | OpenSSH is a derivative of the original and free | |
280 | ssh 1.2.12 release by Tatu Ylonen. | |
281 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
282 | Theo de Raadt and Dug Song | |
283 | removed many bugs, re-added newer features and | |
284 | created OpenSSH. | |
285 | Markus Friedl contributed the support for SSH | |
286 | protocol versions 1.5 and 2.0. | |
287 | .Sh SEE ALSO | |
288 | .Xr ssh 1 , | |
289 | .Xr ssh-add 1 , | |
290 | .Xr ssh-agent 1 , | |
291 | .Xr sshd 8 | |
292 | .Rs | |
293 | .%A J. Galbraith | |
294 | .%A R. Thayer | |
295 | .%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 |