Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.37
1.37 ! markus 1: .\" $OpenBSD: ssh-keygen.1,v 1.36 2001/04/10 09:13:21 itojun 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
1.37 ! markus 84: defaults to generating a RSA1 key for use by protocols 1.3 and 1.5;
1.15 deraadt 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
1.37 ! 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
146: passphrase if the key has one, and for the new comment.
1.37 ! markus 147: .It Fl e
! 148: This option will read a private OpenSSH key file and print the key in a
! 149: .Sq SECSH Public Key File Format
! 150: to stdout.
! 151: This option allows exporting keys for use by several commercial
! 152: SSH implementations.
1.9 markus 153: .It Fl f
154: Specifies the filename of the key file.
1.37 ! markus 155: .It Fl i
! 156: This option will read an unencrypted private (or public) key file
! 157: in SSH2-compatible format and print an OpenSSH compatible private
! 158: (or public) key to stdout.
! 159: .Nm
! 160: does also read the
! 161: .Sq SECSH Public Key File Format .
! 162: This option allows importing keys from several commercial
! 163: SSH implementations.
1.9 markus 164: .It Fl l
165: Show fingerprint of specified private or public key file.
1.2 deraadt 166: .It Fl p
1.1 deraadt 167: Requests changing the passphrase of a private key file instead of
1.12 aaron 168: creating a new private key.
169: The program will prompt for the file
1.1 deraadt 170: containing the private key, for the old passphrase, and twice for the
171: new passphrase.
1.5 aaron 172: .It Fl q
173: Silence
174: .Nm ssh-keygen .
175: Used by
176: .Pa /etc/rc
177: when creating a new key.
1.37 ! markus 178: .It Fl y
! 179: This option will read a private
! 180: OpenSSH format file and print an OpenSSH public key to stdout.
1.25 markus 181: .It Fl t Ar type
182: Specifies the type of the key to create.
183: The possible values are
184: .Dq rsa1
185: for protocol version 1 and
186: .Dq rsa
187: or
188: .Dq dsa
189: for protocol version 2.
190: The default is
1.31 deraadt 191: .Dq rsa1 .
1.35 markus 192: .It Fl B
193: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 194: .It Fl C Ar comment
1.1 deraadt 195: Provides the new comment.
1.2 deraadt 196: .It Fl N Ar new_passphrase
1.1 deraadt 197: Provides the new passphrase.
1.2 deraadt 198: .It Fl P Ar passphrase
1.1 deraadt 199: Provides the (old) passphrase.
1.2 deraadt 200: .El
201: .Sh FILES
202: .Bl -tag -width Ds
203: .It Pa $HOME/.ssh/identity
1.36 itojun 204: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 205: This file should not be readable by anyone but the user.
206: It is possible to
1.1 deraadt 207: specify a passphrase when generating the key; that passphrase will be
1.12 aaron 208: used to encrypt the private part of this file using 3DES.
209: This file is not automatically accessed by
1.2 deraadt 210: .Nm
1.1 deraadt 211: but it is offered as the default file for the private key.
1.15 deraadt 212: .Xr sshd 8
213: will read this file when a login attempt is made.
1.2 deraadt 214: .It Pa $HOME/.ssh/identity.pub
1.36 itojun 215: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 216: The contents of this file should be added to
1.2 deraadt 217: .Pa $HOME/.ssh/authorized_keys
218: on all machines
1.12 aaron 219: where you wish to log in using RSA authentication.
1.15 deraadt 220: There is no need to keep the contents of this file secret.
221: .It Pa $HOME/.ssh/id_dsa
1.36 itojun 222: Contains the protocol version 2 DSA authentication identity of the user.
1.15 deraadt 223: This file should not be readable by anyone but the user.
224: It is possible to
225: specify a passphrase when generating the key; that passphrase will be
226: used to encrypt the private part of this file using 3DES.
227: This file is not automatically accessed by
228: .Nm
229: but it is offered as the default file for the private key.
230: .Xr sshd 8
231: will read this file when a login attempt is made.
232: .It Pa $HOME/.ssh/id_dsa.pub
1.36 itojun 233: Contains the protocol version 2 DSA public key for authentication.
234: The contents of this file should be added to
235: .Pa $HOME/.ssh/authorized_keys2
236: on all machines
237: where you wish to log in using public key authentication.
238: There is no need to keep the contents of this file secret.
239: .It Pa $HOME/.ssh/id_rsa
240: Contains the protocol version 2 RSA authentication identity of the user.
241: This file should not be readable by anyone but the user.
242: It is possible to
243: specify a passphrase when generating the key; that passphrase will be
244: used to encrypt the private part of this file using 3DES.
245: This file is not automatically accessed by
246: .Nm
247: but it is offered as the default file for the private key.
248: .Xr sshd 8
249: will read this file when a login attempt is made.
250: .It Pa $HOME/.ssh/id_rsa.pub
251: Contains the protocol version 2 RSA public key for authentication.
1.15 deraadt 252: The contents of this file should be added to
253: .Pa $HOME/.ssh/authorized_keys2
254: on all machines
1.25 markus 255: where you wish to log in using public key authentication.
1.12 aaron 256: There is no need to keep the contents of this file secret.
1.19 aaron 257: .El
1.24 aaron 258: .Sh AUTHORS
1.28 markus 259: OpenSSH is a derivative of the original and free
260: ssh 1.2.12 release by Tatu Ylonen.
261: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
262: Theo de Raadt and Dug Song
263: removed many bugs, re-added newer features and
264: created OpenSSH.
265: Markus Friedl contributed the support for SSH
266: protocol versions 1.5 and 2.0.
1.2 deraadt 267: .Sh SEE ALSO
268: .Xr ssh 1 ,
269: .Xr ssh-add 1 ,
1.8 ericj 270: .Xr ssh-agent 1 ,
1.30 itojun 271: .Xr sshd 8
1.37 ! markus 272: .Rs
! 273: .%A J. Galbraith
! 274: .%A R. Thayer
! 275: .%T "SECSH Public Key File Format"
! 276: .%N draft-ietf-secsh-publickeyfile-01.txt
! 277: .%D March 2001
! 278: .%O work in progress material
! 279: .Re