Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.54
1.54 ! deraadt 1: .\" $OpenBSD: ssh-keygen.1,v 1.53 2002/02/16 14:53:37 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.
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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
1.53 stevesk 50: .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
1.48 jakob 79: .Nm ssh-keygen
80: .Fl D Ar reader
81: .Nm ssh-keygen
82: .Fl U Ar reader
83: .Op Fl f Ar input_keyfile
1.13 aaron 84: .Sh DESCRIPTION
1.2 deraadt 85: .Nm
1.37 markus 86: generates, manages and converts authentication keys for
1.2 deraadt 87: .Xr ssh 1 .
1.15 deraadt 88: .Nm
1.54 ! deraadt 89: can create RSA keys for use by SSH protocol version 1 and RSA or DSA
1.52 djm 90: keys for use by SSH protocol version 2. The type of key to be generated
91: is specified with the
1.25 markus 92: .Fl t
1.52 djm 93: option.
1.15 deraadt 94: .Pp
1.2 deraadt 95: Normally each user wishing to use SSH
1.15 deraadt 96: with RSA or DSA authentication runs this once to create the authentication
1.1 deraadt 97: key in
1.36 itojun 98: .Pa $HOME/.ssh/identity ,
99: .Pa $HOME/.ssh/id_dsa
1.15 deraadt 100: or
1.36 itojun 101: .Pa $HOME/.ssh/id_rsa .
1.15 deraadt 102: Additionally, the system administrator may use this to generate host keys,
103: as seen in
104: .Pa /etc/rc .
1.2 deraadt 105: .Pp
1.1 deraadt 106: Normally this program generates the key and asks for a file in which
1.12 aaron 107: to store the private key.
108: The public key is stored in a file with the same name but
1.2 deraadt 109: .Dq .pub
1.12 aaron 110: appended.
111: The program also asks for a passphrase.
112: The passphrase may be empty to indicate no passphrase
1.26 markus 113: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 114: arbitrary length.
1.51 stevesk 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
117: characters you want.
118: Good passphrases are 10-30 characters long, are
1.1 deraadt 119: not simple sentences or otherwise easily guessable (English
1.42 markus 120: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 121: passphrases), and contain a mix of upper and lowercase letters,
122: numbers, and non-alphanumeric characters.
1.12 aaron 123: The passphrase can be changed later by using the
1.2 deraadt 124: .Fl p
1.1 deraadt 125: option.
1.2 deraadt 126: .Pp
1.12 aaron 127: There is no way to recover a lost passphrase.
128: If the passphrase is
1.49 deraadt 129: lost or forgotten, a new key must be generated and copied to the
1.1 deraadt 130: corresponding public key to other machines.
1.2 deraadt 131: .Pp
1.37 markus 132: For RSA1 keys,
133: there is also a comment field in the key file that is only for
1.12 aaron 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
1.2 deraadt 137: .Dq user@host
138: when the key is created, but can be changed using the
139: .Fl c
1.1 deraadt 140: option.
1.2 deraadt 141: .Pp
1.15 deraadt 142: After a key is generated, instructions below detail where the keys
143: should be placed to be activated.
144: .Pp
1.2 deraadt 145: The options are as follows:
146: .Bl -tag -width Ds
147: .It Fl b Ar bits
1.12 aaron 148: Specifies the number of bits in the key to create.
149: Minimum is 512 bits.
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.
1.2 deraadt 153: .It Fl c
1.1 deraadt 154: Requests changing the comment in the private and public key files.
1.50 markus 155: This operation is only supported for RSA1 keys.
1.1 deraadt 156: The program will prompt for the file containing the private keys, for
1.41 stevesk 157: the passphrase if the key has one, and for the new comment.
1.37 markus 158: .It Fl e
1.40 markus 159: This option will read a private or public OpenSSH key file and
160: print the key in a
1.37 markus 161: .Sq SECSH Public Key File Format
162: to stdout.
163: This option allows exporting keys for use by several commercial
164: SSH implementations.
1.48 jakob 165: .It Fl f Ar filename
1.9 markus 166: Specifies the filename of the key file.
1.37 markus 167: .It Fl i
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.
171: .Nm
1.38 markus 172: also reads the
1.37 markus 173: .Sq SECSH Public Key File Format .
174: This option allows importing keys from several commercial
175: SSH implementations.
1.9 markus 176: .It Fl l
1.50 markus 177: Show fingerprint of specified public key file.
178: Private RSA1 keys are also supported.
179: For RSA and DSA keys
180: .Nm
181: tries to find the matching public key file and prints its fingerprint.
1.2 deraadt 182: .It Fl p
1.1 deraadt 183: Requests changing the passphrase of a private key file instead of
1.12 aaron 184: creating a new private key.
185: The program will prompt for the file
1.1 deraadt 186: containing the private key, for the old passphrase, and twice for the
187: new passphrase.
1.5 aaron 188: .It Fl q
189: Silence
190: .Nm ssh-keygen .
191: Used by
192: .Pa /etc/rc
193: when creating a new key.
1.37 markus 194: .It Fl y
195: This option will read a private
196: OpenSSH format file and print an OpenSSH public key to stdout.
1.25 markus 197: .It Fl t Ar type
198: Specifies the type of the key to create.
199: The possible values are
200: .Dq rsa1
201: for protocol version 1 and
202: .Dq rsa
203: or
204: .Dq dsa
205: for protocol version 2.
1.35 markus 206: .It Fl B
207: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 208: .It Fl C Ar comment
1.1 deraadt 209: Provides the new comment.
1.48 jakob 210: .It Fl D Ar reader
211: Download the RSA public key stored in the smartcard in
212: .Ar reader .
1.2 deraadt 213: .It Fl N Ar new_passphrase
1.1 deraadt 214: Provides the new passphrase.
1.2 deraadt 215: .It Fl P Ar passphrase
1.1 deraadt 216: Provides the (old) passphrase.
1.48 jakob 217: .It Fl U Ar reader
218: Upload an existing RSA private key into the smartcard in
219: .Ar reader .
1.2 deraadt 220: .El
221: .Sh FILES
222: .Bl -tag -width Ds
223: .It Pa $HOME/.ssh/identity
1.36 itojun 224: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 225: This file should not be readable by anyone but the user.
226: It is possible to
1.1 deraadt 227: specify a passphrase when generating the key; that passphrase will be
1.12 aaron 228: used to encrypt the private part of this file using 3DES.
229: This file is not automatically accessed by
1.2 deraadt 230: .Nm
1.1 deraadt 231: but it is offered as the default file for the private key.
1.46 markus 232: .Xr ssh 1
1.15 deraadt 233: will read this file when a login attempt is made.
1.2 deraadt 234: .It Pa $HOME/.ssh/identity.pub
1.36 itojun 235: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 236: The contents of this file should be added to
1.2 deraadt 237: .Pa $HOME/.ssh/authorized_keys
238: on all machines
1.49 deraadt 239: where the user wishes to log in using RSA authentication.
1.15 deraadt 240: There is no need to keep the contents of this file secret.
241: .It Pa $HOME/.ssh/id_dsa
1.36 itojun 242: Contains the protocol version 2 DSA authentication identity of the user.
1.15 deraadt 243: This file should not be readable by anyone but the user.
244: It is possible to
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
248: .Nm
249: but it is offered as the default file for the private key.
1.46 markus 250: .Xr ssh 1
1.15 deraadt 251: will read this file when a login attempt is made.
252: .It Pa $HOME/.ssh/id_dsa.pub
1.36 itojun 253: Contains the protocol version 2 DSA public key for authentication.
254: The contents of this file should be added to
1.43 markus 255: .Pa $HOME/.ssh/authorized_keys
1.36 itojun 256: on all machines
1.49 deraadt 257: where the user wishes to log in using public key authentication.
1.36 itojun 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.
262: It is possible to
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
266: .Nm
267: but it is offered as the default file for the private key.
1.46 markus 268: .Xr ssh 1
1.36 itojun 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.
1.15 deraadt 272: The contents of this file should be added to
1.43 markus 273: .Pa $HOME/.ssh/authorized_keys
1.15 deraadt 274: on all machines
1.49 deraadt 275: where the user wishes to log in using public key authentication.
1.12 aaron 276: There is no need to keep the contents of this file secret.
1.19 aaron 277: .El
1.24 aaron 278: .Sh AUTHORS
1.28 markus 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
284: created OpenSSH.
285: Markus Friedl contributed the support for SSH
286: protocol versions 1.5 and 2.0.
1.2 deraadt 287: .Sh SEE ALSO
288: .Xr ssh 1 ,
289: .Xr ssh-add 1 ,
1.8 ericj 290: .Xr ssh-agent 1 ,
1.30 itojun 291: .Xr sshd 8
1.37 markus 292: .Rs
1.45 deraadt 293: .%A J. Galbraith
294: .%A R. Thayer
1.37 markus 295: .%T "SECSH Public Key File Format"
296: .%N draft-ietf-secsh-publickeyfile-01.txt
297: .%D March 2001
298: .%O work in progress material
299: .Re