Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.36
1.36 ! itojun 1: .\" $OpenBSD: ssh-keygen.1,v 1.35 2001/03/11 22:33:23 markus 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
45: .Nd authentication key generation
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
1.16 deraadt 60: .Fl x
1.20 markus 61: .Op Fl f Ar input_keyfile
1.16 deraadt 62: .Nm ssh-keygen
63: .Fl X
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
1.13 aaron 81: generates and manages authentication keys for
1.2 deraadt 82: .Xr ssh 1 .
1.15 deraadt 83: .Nm
84: defaults to generating an RSA key for use by protocols 1.3 and 1.5;
85: specifying the
1.25 markus 86: .Fl t
1.26 markus 87: option allows you to create a key for use by protocol 2.0.
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
111: prose has only 1-2 bits of entropy per word, 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
1.15 deraadt 122: For RSA, there is also a comment field in the key file that is only for
1.12 aaron 123: convenience to the user to help identify the key.
124: The comment can tell what the key is for, or whatever is useful.
125: The comment is initialized to
1.2 deraadt 126: .Dq user@host
127: when the key is created, but can be changed using the
128: .Fl c
1.1 deraadt 129: option.
1.2 deraadt 130: .Pp
1.15 deraadt 131: After a key is generated, instructions below detail where the keys
132: should be placed to be activated.
133: .Pp
1.2 deraadt 134: The options are as follows:
135: .Bl -tag -width Ds
136: .It Fl b Ar bits
1.12 aaron 137: Specifies the number of bits in the key to create.
138: Minimum is 512 bits.
139: Generally 1024 bits is considered sufficient, and key sizes
140: above that no longer improve security but make things slower.
141: The default is 1024 bits.
1.2 deraadt 142: .It Fl c
1.1 deraadt 143: Requests changing the comment in the private and public key files.
144: The program will prompt for the file containing the private keys, for
145: passphrase if the key has one, and for the new comment.
1.9 markus 146: .It Fl f
147: Specifies the filename of the key file.
148: .It Fl l
149: Show fingerprint of specified private or public key file.
1.2 deraadt 150: .It Fl p
1.1 deraadt 151: Requests changing the passphrase of a private key file instead of
1.12 aaron 152: creating a new private key.
153: The program will prompt for the file
1.1 deraadt 154: containing the private key, for the old passphrase, and twice for the
155: new passphrase.
1.5 aaron 156: .It Fl q
157: Silence
158: .Nm ssh-keygen .
159: Used by
160: .Pa /etc/rc
161: when creating a new key.
1.25 markus 162: .It Fl t Ar type
163: Specifies the type of the key to create.
164: The possible values are
165: .Dq rsa1
166: for protocol version 1 and
167: .Dq rsa
168: or
169: .Dq dsa
170: for protocol version 2.
171: The default is
1.31 deraadt 172: .Dq rsa1 .
1.35 markus 173: .It Fl B
174: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 175: .It Fl C Ar comment
1.1 deraadt 176: Provides the new comment.
1.2 deraadt 177: .It Fl N Ar new_passphrase
1.1 deraadt 178: Provides the new passphrase.
1.2 deraadt 179: .It Fl P Ar passphrase
1.1 deraadt 180: Provides the (old) passphrase.
1.16 deraadt 181: .It Fl x
1.17 markus 182: This option will read a private
1.18 hugh 183: OpenSSH DSA format file and print a SSH2-compatible public key to stdout.
1.16 deraadt 184: .It Fl X
1.23 markus 185: This option will read a unencrypted
186: SSH2-compatible private (or public) key file and
187: print an OpenSSH compatible private (or public) key to stdout.
1.17 markus 188: .It Fl y
189: This option will read a private
1.25 markus 190: OpenSSH format file and print an OpenSSH public key to stdout.
1.2 deraadt 191: .El
192: .Sh FILES
193: .Bl -tag -width Ds
194: .It Pa $HOME/.ssh/identity
1.36 ! itojun 195: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 196: This file should not be readable by anyone but the user.
197: It is possible to
1.1 deraadt 198: specify a passphrase when generating the key; that passphrase will be
1.12 aaron 199: used to encrypt the private part of this file using 3DES.
200: This file is not automatically accessed by
1.2 deraadt 201: .Nm
1.1 deraadt 202: but it is offered as the default file for the private key.
1.15 deraadt 203: .Xr sshd 8
204: will read this file when a login attempt is made.
1.2 deraadt 205: .It Pa $HOME/.ssh/identity.pub
1.36 ! itojun 206: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 207: The contents of this file should be added to
1.2 deraadt 208: .Pa $HOME/.ssh/authorized_keys
209: on all machines
1.12 aaron 210: where you wish to log in using RSA authentication.
1.15 deraadt 211: There is no need to keep the contents of this file secret.
212: .It Pa $HOME/.ssh/id_dsa
1.36 ! itojun 213: Contains the protocol version 2 DSA authentication identity of the user.
1.15 deraadt 214: This file should not be readable by anyone but the user.
215: It is possible to
216: specify a passphrase when generating the key; that passphrase will be
217: used to encrypt the private part of this file using 3DES.
218: This file is not automatically accessed by
219: .Nm
220: but it is offered as the default file for the private key.
221: .Xr sshd 8
222: will read this file when a login attempt is made.
223: .It Pa $HOME/.ssh/id_dsa.pub
1.36 ! itojun 224: Contains the protocol version 2 DSA public key for authentication.
! 225: The contents of this file should be added to
! 226: .Pa $HOME/.ssh/authorized_keys2
! 227: on all machines
! 228: where you wish to log in using public key authentication.
! 229: There is no need to keep the contents of this file secret.
! 230: .It Pa $HOME/.ssh/id_rsa
! 231: Contains the protocol version 2 RSA authentication identity of the user.
! 232: This file should not be readable by anyone but the user.
! 233: It is possible to
! 234: specify a passphrase when generating the key; that passphrase will be
! 235: used to encrypt the private part of this file using 3DES.
! 236: This file is not automatically accessed by
! 237: .Nm
! 238: but it is offered as the default file for the private key.
! 239: .Xr sshd 8
! 240: will read this file when a login attempt is made.
! 241: .It Pa $HOME/.ssh/id_rsa.pub
! 242: Contains the protocol version 2 RSA public key for authentication.
1.15 deraadt 243: The contents of this file should be added to
244: .Pa $HOME/.ssh/authorized_keys2
245: on all machines
1.25 markus 246: where you wish to log in using public key authentication.
1.12 aaron 247: There is no need to keep the contents of this file secret.
1.19 aaron 248: .El
1.24 aaron 249: .Sh AUTHORS
1.28 markus 250: OpenSSH is a derivative of the original and free
251: ssh 1.2.12 release by Tatu Ylonen.
252: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
253: Theo de Raadt and Dug Song
254: removed many bugs, re-added newer features and
255: created OpenSSH.
256: Markus Friedl contributed the support for SSH
257: protocol versions 1.5 and 2.0.
1.2 deraadt 258: .Sh SEE ALSO
259: .Xr ssh 1 ,
260: .Xr ssh-add 1 ,
1.8 ericj 261: .Xr ssh-agent 1 ,
1.30 itojun 262: .Xr sshd 8
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