1 .\" $OpenBSD: ssh-keygen.1,v 1.48 2001/08/02 15:07:23 jakob 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
83 .Op Fl f Ar input_keyfile
86 generates, manages and converts authentication keys for
89 defaults to generating a RSA1 key for use by SSH protocol version 1.
92 option allows you to create a key for use by SSH protocol version 2.
94 Normally each user wishing to use SSH
95 with RSA or DSA authentication runs this once to create the authentication
97 .Pa $HOME/.ssh/identity ,
100 .Pa $HOME/.ssh/id_rsa .
101 Additionally, the system administrator may use this to generate host keys,
105 Normally this program generates the key and asks for a file in which
106 to store the private key.
107 The public key is stored in a file with the same name but
110 The program also asks for a passphrase.
111 The passphrase may be empty to indicate no passphrase
112 (host keys must have an empty passphrase), or it may be a string of
114 Good passphrases are 10-30 characters long and are
115 not simple sentences or otherwise easily guessable (English
116 prose has only 1-2 bits of entropy per character, and provides very bad
118 The passphrase can be changed later by using the
122 There is no way to recover a lost passphrase.
124 lost or forgotten, you will have to generate a new key and copy the
125 corresponding public key to other machines.
128 there is also a comment field in the key file that is only for
129 convenience to the user to help identify the key.
130 The comment can tell what the key is for, or whatever is useful.
131 The comment is initialized to
133 when the key is created, but can be changed using the
137 After a key is generated, instructions below detail where the keys
138 should be placed to be activated.
140 The options are as follows:
143 Specifies the number of bits in the key to create.
145 Generally 1024 bits is considered sufficient, and key sizes
146 above that no longer improve security but make things slower.
147 The default is 1024 bits.
149 Requests changing the comment in the private and public key files.
150 The program will prompt for the file containing the private keys, for
151 the passphrase if the key has one, and for the new comment.
153 This option will read a private or public OpenSSH key file and
155 .Sq SECSH Public Key File Format
157 This option allows exporting keys for use by several commercial
160 Specifies the filename of the key file.
162 This option will read an unencrypted private (or public) key file
163 in SSH2-compatible format and print an OpenSSH compatible private
164 (or public) key to stdout.
167 .Sq SECSH Public Key File Format .
168 This option allows importing keys from several commercial
171 Show fingerprint of specified private or public key file.
173 Requests changing the passphrase of a private key file instead of
174 creating a new private key.
175 The program will prompt for the file
176 containing the private key, for the old passphrase, and twice for the
183 when creating a new key.
185 This option will read a private
186 OpenSSH format file and print an OpenSSH public key to stdout.
188 Specifies the type of the key to create.
189 The possible values are
191 for protocol version 1 and
195 for protocol version 2.
199 Show the bubblebabble digest of specified private or public key file.
201 Provides the new comment.
203 Download the RSA public key stored in the smartcard in
205 .It Fl N Ar new_passphrase
206 Provides the new passphrase.
207 .It Fl P Ar passphrase
208 Provides the (old) passphrase.
210 Upload an existing RSA private key into the smartcard in
215 .It Pa $HOME/.ssh/identity
216 Contains the protocol version 1 RSA authentication identity of the user.
217 This file should not be readable by anyone but the user.
219 specify a passphrase when generating the key; that passphrase will be
220 used to encrypt the private part of this file using 3DES.
221 This file is not automatically accessed by
223 but it is offered as the default file for the private key.
225 will read this file when a login attempt is made.
226 .It Pa $HOME/.ssh/identity.pub
227 Contains the protocol version 1 RSA public key for authentication.
228 The contents of this file should be added to
229 .Pa $HOME/.ssh/authorized_keys
231 where you wish to log in using RSA authentication.
232 There is no need to keep the contents of this file secret.
233 .It Pa $HOME/.ssh/id_dsa
234 Contains the protocol version 2 DSA authentication identity of the user.
235 This file should not be readable by anyone but the user.
237 specify a passphrase when generating the key; that passphrase will be
238 used to encrypt the private part of this file using 3DES.
239 This file is not automatically accessed by
241 but it is offered as the default file for the private key.
243 will read this file when a login attempt is made.
244 .It Pa $HOME/.ssh/id_dsa.pub
245 Contains the protocol version 2 DSA public key for authentication.
246 The contents of this file should be added to
247 .Pa $HOME/.ssh/authorized_keys
249 where you wish to log in using public key authentication.
250 There is no need to keep the contents of this file secret.
251 .It Pa $HOME/.ssh/id_rsa
252 Contains the protocol version 2 RSA authentication identity of the user.
253 This file should not be readable by anyone but the user.
255 specify a passphrase when generating the key; that passphrase will be
256 used to encrypt the private part of this file using 3DES.
257 This file is not automatically accessed by
259 but it is offered as the default file for the private key.
261 will read this file when a login attempt is made.
262 .It Pa $HOME/.ssh/id_rsa.pub
263 Contains the protocol version 2 RSA public key for authentication.
264 The contents of this file should be added to
265 .Pa $HOME/.ssh/authorized_keys
267 where you wish to log in using public key authentication.
268 There is no need to keep the contents of this file secret.
271 OpenSSH is a derivative of the original and free
272 ssh 1.2.12 release by Tatu Ylonen.
273 Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
274 Theo de Raadt and Dug Song
275 removed many bugs, re-added newer features and
277 Markus Friedl contributed the support for SSH
278 protocol versions 1.5 and 2.0.
287 .%T "SECSH Public Key File Format"
288 .%N draft-ietf-secsh-publickeyfile-01.txt
290 .%O work in progress material