1 .\" $OpenBSD: ssh-keygen.1,v 1.53 2002/02/16 14:53:37 stevesk 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 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
95 Normally each user wishing to use SSH
96 with RSA or DSA authentication runs this once to create the authentication
98 .Pa $HOME/.ssh/identity ,
101 .Pa $HOME/.ssh/id_rsa .
102 Additionally, the system administrator may use this to generate host keys,
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
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
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
118 Good passphrases are 10-30 characters long, are
119 not simple sentences or otherwise easily guessable (English
120 prose has only 1-2 bits of entropy per character, and provides very bad
121 passphrases), and contain a mix of upper and lowercase letters,
122 numbers, and non-alphanumeric characters.
123 The passphrase can be changed later by using the
127 There is no way to recover a lost passphrase.
129 lost or forgotten, a new key must be generated and copied to the
130 corresponding public key to other machines.
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
138 when the key is created, but can be changed using the
142 After a key is generated, instructions below detail where the keys
143 should be placed to be activated.
145 The options are as follows:
148 Specifies the number of bits in the key to create.
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.
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.
159 This option will read a private or public OpenSSH key file and
161 .Sq SECSH Public Key File Format
163 This option allows exporting keys for use by several commercial
166 Specifies the filename of the key file.
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.
173 .Sq SECSH Public Key File Format .
174 This option allows importing keys from several commercial
177 Show fingerprint of specified public key file.
178 Private RSA1 keys are also supported.
181 tries to find the matching public key file and prints its fingerprint.
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
193 when creating a new key.
195 This option will read a private
196 OpenSSH format file and print an OpenSSH public key to stdout.
198 Specifies the type of the key to create.
199 The possible values are
201 for protocol version 1 and
205 for protocol version 2.
207 Show the bubblebabble digest of specified private or public key file.
209 Provides the new comment.
211 Download the RSA public key stored in the smartcard in
213 .It Fl N Ar new_passphrase
214 Provides the new passphrase.
215 .It Fl P Ar passphrase
216 Provides the (old) passphrase.
218 Upload an existing RSA private key into the smartcard in
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.
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
231 but it is offered as the default file for the private key.
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
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.
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
249 but it is offered as the default file for the private key.
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
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.
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
267 but it is offered as the default file for the private key.
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
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.
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
285 Markus Friedl contributed the support for SSH
286 protocol versions 1.5 and 2.0.
295 .%T "SECSH Public Key File Format"
296 .%N draft-ietf-secsh-publickeyfile-01.txt
298 .%O work in progress material