Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.42
1.42 ! markus 1: .\" $OpenBSD: ssh-keygen.1,v 1.41 2001/05/05 13:42:52 stevesk Exp $
1.29 niklas 2: .\"
1.1 deraadt 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: .\"
1.22 deraadt 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: .\"
1.33 deraadt 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.
1.22 deraadt 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.
1.1 deraadt 28: .\"
1.22 deraadt 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.
1.1 deraadt 39: .\"
1.2 deraadt 40: .Dd September 25, 1999
41: .Dt SSH-KEYGEN 1
42: .Os
43: .Sh NAME
44: .Nm ssh-keygen
1.37 markus 45: .Nd authentication key generation, management and conversion
1.2 deraadt 46: .Sh SYNOPSIS
47: .Nm ssh-keygen
1.25 markus 48: .Op Fl q
1.2 deraadt 49: .Op Fl b Ar bits
1.25 markus 50: .Op Fl t Ar type
1.2 deraadt 51: .Op Fl N Ar new_passphrase
52: .Op Fl C Ar comment
1.20 markus 53: .Op Fl f Ar output_keyfile
1.2 deraadt 54: .Nm ssh-keygen
55: .Fl p
56: .Op Fl P Ar old_passphrase
57: .Op Fl N Ar new_passphrase
1.9 markus 58: .Op Fl f Ar keyfile
1.2 deraadt 59: .Nm ssh-keygen
1.37 markus 60: .Fl i
1.20 markus 61: .Op Fl f Ar input_keyfile
1.16 deraadt 62: .Nm ssh-keygen
1.37 markus 63: .Fl e
1.20 markus 64: .Op Fl f Ar input_keyfile
1.16 deraadt 65: .Nm ssh-keygen
1.17 markus 66: .Fl y
1.20 markus 67: .Op Fl f Ar input_keyfile
1.17 markus 68: .Nm ssh-keygen
1.2 deraadt 69: .Fl c
70: .Op Fl P Ar passphrase
71: .Op Fl C Ar comment
1.9 markus 72: .Op Fl f Ar keyfile
73: .Nm ssh-keygen
74: .Fl l
1.35 markus 75: .Op Fl f Ar input_keyfile
76: .Nm ssh-keygen
77: .Fl B
1.20 markus 78: .Op Fl f Ar input_keyfile
1.13 aaron 79: .Sh DESCRIPTION
1.2 deraadt 80: .Nm
1.37 markus 81: generates, manages and converts authentication keys for
1.2 deraadt 82: .Xr ssh 1 .
1.15 deraadt 83: .Nm
1.39 markus 84: defaults to generating a RSA1 key for use by SSH protocol version 1.
1.15 deraadt 85: specifying the
1.25 markus 86: .Fl t
1.39 markus 87: option allows you to create a key for use by SSH protocol version 2.
1.15 deraadt 88: .Pp
1.2 deraadt 89: Normally each user wishing to use SSH
1.15 deraadt 90: with RSA or DSA authentication runs this once to create the authentication
1.1 deraadt 91: key in
1.36 itojun 92: .Pa $HOME/.ssh/identity ,
93: .Pa $HOME/.ssh/id_dsa
1.15 deraadt 94: or
1.36 itojun 95: .Pa $HOME/.ssh/id_rsa .
1.15 deraadt 96: Additionally, the system administrator may use this to generate host keys,
97: as seen in
98: .Pa /etc/rc .
1.2 deraadt 99: .Pp
1.1 deraadt 100: Normally this program generates the key and asks for a file in which
1.12 aaron 101: to store the private key.
102: The public key is stored in a file with the same name but
1.2 deraadt 103: .Dq .pub
1.12 aaron 104: appended.
105: The program also asks for a passphrase.
106: The passphrase may be empty to indicate no passphrase
1.26 markus 107: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 108: arbitrary length.
109: Good passphrases are 10-30 characters long and are
1.1 deraadt 110: not simple sentences or otherwise easily guessable (English
1.42 ! markus 111: prose has only 1-2 bits of entropy per character, and provides very bad
1.12 aaron 112: passphrases).
113: The passphrase can be changed later by using the
1.2 deraadt 114: .Fl p
1.1 deraadt 115: option.
1.2 deraadt 116: .Pp
1.12 aaron 117: There is no way to recover a lost passphrase.
118: If the passphrase is
1.1 deraadt 119: lost or forgotten, you will have to generate a new key and copy the
120: corresponding public key to other machines.
1.2 deraadt 121: .Pp
1.37 markus 122: For RSA1 keys,
123: there is also a comment field in the key file that is only for
1.12 aaron 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
1.2 deraadt 127: .Dq user@host
128: when the key is created, but can be changed using the
129: .Fl c
1.1 deraadt 130: option.
1.2 deraadt 131: .Pp
1.15 deraadt 132: After a key is generated, instructions below detail where the keys
133: should be placed to be activated.
134: .Pp
1.2 deraadt 135: The options are as follows:
136: .Bl -tag -width Ds
137: .It Fl b Ar bits
1.12 aaron 138: Specifies the number of bits in the key to create.
139: Minimum is 512 bits.
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.
1.2 deraadt 143: .It Fl c
1.1 deraadt 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
1.41 stevesk 146: the passphrase if the key has one, and for the new comment.
1.37 markus 147: .It Fl e
1.40 markus 148: This option will read a private or public OpenSSH key file and
149: print the key in a
1.37 markus 150: .Sq SECSH Public Key File Format
151: to stdout.
152: This option allows exporting keys for use by several commercial
153: SSH implementations.
1.9 markus 154: .It Fl f
155: Specifies the filename of the key file.
1.37 markus 156: .It Fl i
157: This option will read an unencrypted private (or public) key file
158: in SSH2-compatible format and print an OpenSSH compatible private
159: (or public) key to stdout.
160: .Nm
1.38 markus 161: also reads the
1.37 markus 162: .Sq SECSH Public Key File Format .
163: This option allows importing keys from several commercial
164: SSH implementations.
1.9 markus 165: .It Fl l
166: Show fingerprint of specified private or public key file.
1.2 deraadt 167: .It Fl p
1.1 deraadt 168: Requests changing the passphrase of a private key file instead of
1.12 aaron 169: creating a new private key.
170: The program will prompt for the file
1.1 deraadt 171: containing the private key, for the old passphrase, and twice for the
172: new passphrase.
1.5 aaron 173: .It Fl q
174: Silence
175: .Nm ssh-keygen .
176: Used by
177: .Pa /etc/rc
178: when creating a new key.
1.37 markus 179: .It Fl y
180: This option will read a private
181: OpenSSH format file and print an OpenSSH public key to stdout.
1.25 markus 182: .It Fl t Ar type
183: Specifies the type of the key to create.
184: The possible values are
185: .Dq rsa1
186: for protocol version 1 and
187: .Dq rsa
188: or
189: .Dq dsa
190: for protocol version 2.
191: The default is
1.31 deraadt 192: .Dq rsa1 .
1.35 markus 193: .It Fl B
194: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 195: .It Fl C Ar comment
1.1 deraadt 196: Provides the new comment.
1.2 deraadt 197: .It Fl N Ar new_passphrase
1.1 deraadt 198: Provides the new passphrase.
1.2 deraadt 199: .It Fl P Ar passphrase
1.1 deraadt 200: Provides the (old) passphrase.
1.2 deraadt 201: .El
202: .Sh FILES
203: .Bl -tag -width Ds
204: .It Pa $HOME/.ssh/identity
1.36 itojun 205: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 206: This file should not be readable by anyone but the user.
207: It is possible to
1.1 deraadt 208: specify a passphrase when generating the key; that passphrase will be
1.12 aaron 209: used to encrypt the private part of this file using 3DES.
210: This file is not automatically accessed by
1.2 deraadt 211: .Nm
1.1 deraadt 212: but it is offered as the default file for the private key.
1.15 deraadt 213: .Xr sshd 8
214: will read this file when a login attempt is made.
1.2 deraadt 215: .It Pa $HOME/.ssh/identity.pub
1.36 itojun 216: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 217: The contents of this file should be added to
1.2 deraadt 218: .Pa $HOME/.ssh/authorized_keys
219: on all machines
1.12 aaron 220: where you wish to log in using RSA authentication.
1.15 deraadt 221: There is no need to keep the contents of this file secret.
222: .It Pa $HOME/.ssh/id_dsa
1.36 itojun 223: Contains the protocol version 2 DSA authentication identity of the user.
1.15 deraadt 224: This file should not be readable by anyone but the user.
225: It is possible to
226: specify a passphrase when generating the key; that passphrase will be
227: used to encrypt the private part of this file using 3DES.
228: This file is not automatically accessed by
229: .Nm
230: but it is offered as the default file for the private key.
231: .Xr sshd 8
232: will read this file when a login attempt is made.
233: .It Pa $HOME/.ssh/id_dsa.pub
1.36 itojun 234: Contains the protocol version 2 DSA public key for authentication.
235: The contents of this file should be added to
236: .Pa $HOME/.ssh/authorized_keys2
237: on all machines
238: where you wish to log in using public key authentication.
239: There is no need to keep the contents of this file secret.
240: .It Pa $HOME/.ssh/id_rsa
241: Contains the protocol version 2 RSA authentication identity of the user.
242: This file should not be readable by anyone but the user.
243: It is possible to
244: specify a passphrase when generating the key; that passphrase will be
245: used to encrypt the private part of this file using 3DES.
246: This file is not automatically accessed by
247: .Nm
248: but it is offered as the default file for the private key.
249: .Xr sshd 8
250: will read this file when a login attempt is made.
251: .It Pa $HOME/.ssh/id_rsa.pub
252: Contains the protocol version 2 RSA public key for authentication.
1.15 deraadt 253: The contents of this file should be added to
254: .Pa $HOME/.ssh/authorized_keys2
255: on all machines
1.25 markus 256: where you wish to log in using public key authentication.
1.12 aaron 257: There is no need to keep the contents of this file secret.
1.19 aaron 258: .El
1.24 aaron 259: .Sh AUTHORS
1.28 markus 260: OpenSSH is a derivative of the original and free
261: ssh 1.2.12 release by Tatu Ylonen.
262: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
263: Theo de Raadt and Dug Song
264: removed many bugs, re-added newer features and
265: created OpenSSH.
266: Markus Friedl contributed the support for SSH
267: protocol versions 1.5 and 2.0.
1.2 deraadt 268: .Sh SEE ALSO
269: .Xr ssh 1 ,
270: .Xr ssh-add 1 ,
1.8 ericj 271: .Xr ssh-agent 1 ,
1.30 itojun 272: .Xr sshd 8
1.37 markus 273: .Rs
274: .%A J. Galbraith
275: .%A R. Thayer
276: .%T "SECSH Public Key File Format"
277: .%N draft-ietf-secsh-publickeyfile-01.txt
278: .%D March 2001
279: .%O work in progress material
280: .Re
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