3 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 .\" All rights reserved
7 .\" As far as I am concerned, the code I have written for this software
8 .\" can be used freely for any purpose. Any derived versions of this
9 .\" software must be clearly marked as such, and if the derived work is
10 .\" incompatible with the protocol description in the RFC file, it must be
11 .\" called by a name other than "ssh" or "Secure Shell".
14 .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
15 .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
16 .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
18 .\" Redistribution and use in source and binary forms, with or without
19 .\" modification, are permitted provided that the following conditions
21 .\" 1. Redistributions of source code must retain the above copyright
22 .\" notice, this list of conditions and the following disclaimer.
23 .\" 2. Redistributions in binary form must reproduce the above copyright
24 .\" notice, this list of conditions and the following disclaimer in the
25 .\" documentation and/or other materials provided with the distribution.
27 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 .Dd September 25, 1999
43 .Nd authentication key generation
49 .Op Fl N Ar new_passphrase
51 .Op Fl f Ar output_keyfile
54 .Op Fl P Ar old_passphrase
55 .Op Fl N Ar new_passphrase
59 .Op Fl f Ar input_keyfile
62 .Op Fl f Ar input_keyfile
65 .Op Fl f Ar input_keyfile
68 .Op Fl P Ar passphrase
73 .Op Fl f Ar input_keyfile
78 generates and manages authentication keys for
81 defaults to generating an RSA key for use by protocols 1.3 and 1.5;
84 allows you to create a key for use by protocol 2.0.
86 Normally each user wishing to use SSH
87 with RSA or DSA authentication runs this once to create the authentication
89 .Pa $HOME/.ssh/identity
91 .Pa $HOME/.ssh/id_dsa .
92 Additionally, the system administrator may use this to generate host keys,
96 Normally this program generates the key and asks for a file in which
97 to store the private key.
98 The public key is stored in a file with the same name but
101 The program also asks for a passphrase.
102 The passphrase may be empty to indicate no passphrase
103 (host keys must have empty passphrase), or it may be a string of
105 Good passphrases are 10-30 characters long and are
106 not simple sentences or otherwise easily guessable (English
107 prose has only 1-2 bits of entropy per word, and provides very bad
109 The passphrase can be changed later by using the
113 There is no way to recover a lost passphrase.
115 lost or forgotten, you will have to generate a new key and copy the
116 corresponding public key to other machines.
118 For RSA, there is also a comment field in the key file that is only for
119 convenience to the user to help identify the key.
120 The comment can tell what the key is for, or whatever is useful.
121 The comment is initialized to
123 when the key is created, but can be changed using the
127 After a key is generated, instructions below detail where the keys
128 should be placed to be activated.
130 The options are as follows:
133 Specifies the number of bits in the key to create.
135 Generally 1024 bits is considered sufficient, and key sizes
136 above that no longer improve security but make things slower.
137 The default is 1024 bits.
139 Requests changing the comment in the private and public key files.
140 The program will prompt for the file containing the private keys, for
141 passphrase if the key has one, and for the new comment.
143 Specifies the filename of the key file.
145 Show fingerprint of specified private or public key file.
147 Requests changing the passphrase of a private key file instead of
148 creating a new private key.
149 The program will prompt for the file
150 containing the private key, for the old passphrase, and twice for the
157 when creating a new key.
159 Specifies the type of the key to create.
160 The possible values are
162 for protocol version 1 and
166 for protocol version 2.
170 Provides the new comment.
171 .It Fl N Ar new_passphrase
172 Provides the new passphrase.
173 .It Fl P Ar passphrase
174 Provides the (old) passphrase.
176 If RSA support is functional, immediately exits with code 0. If RSA
177 support is not functional, exits with code 1. This flag will be
178 removed once the RSA patent expires.
180 This option will read a private
181 OpenSSH DSA format file and print a SSH2-compatible public key to stdout.
183 This option will read a unencrypted
184 SSH2-compatible private (or public) key file and
185 print an OpenSSH compatible private (or public) key to stdout.
187 This option will read a private
188 OpenSSH format file and print an OpenSSH public key to stdout.
192 .It Pa $HOME/.ssh/identity
193 Contains the RSA authentication identity of the user.
194 This file should not be readable by anyone but the user.
196 specify a passphrase when generating the key; that passphrase will be
197 used to encrypt the private part of this file using 3DES.
198 This file is not automatically accessed by
200 but it is offered as the default file for the private key.
202 will read this file when a login attempt is made.
203 .It Pa $HOME/.ssh/identity.pub
204 Contains the public key for authentication.
205 The contents of this file should be added to
206 .Pa $HOME/.ssh/authorized_keys
208 where you wish to log in using RSA authentication.
209 There is no need to keep the contents of this file secret.
210 .It Pa $HOME/.ssh/id_dsa
211 Contains the DSA authentication identity of the user.
212 This file should not be readable by anyone but the user.
214 specify a passphrase when generating the key; that passphrase will be
215 used to encrypt the private part of this file using 3DES.
216 This file is not automatically accessed by
218 but it is offered as the default file for the private key.
220 will read this file when a login attempt is made.
221 .It Pa $HOME/.ssh/id_dsa.pub
222 Contains the public key for authentication.
223 The contents of this file should be added to
224 .Pa $HOME/.ssh/authorized_keys2
226 where you wish to log in using public key authentication.
227 There is no need to keep the contents of this file secret.
230 Tatu Ylonen <ylo@cs.hut.fi>
233 is a derivative of the original (free) ssh 1.2.12 release, but with bugs
234 removed and newer features re-added.
235 Rapidly after the 1.2.12 release,
236 newer versions bore successively more restrictive licenses.
237 This version of OpenSSH
240 has all components of a restrictive nature (i.e., patents, see
242 directly removed from the source code; any licensed or patented components
246 has been updated to support ssh protocol 1.5.
248 contains added support for
250 authentication and ticket passing.
252 supports one-time password authentication with