diff options
author | Colin Watson <cjwatson@debian.org> | 2003-09-17 00:32:19 +0000 |
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committer | Colin Watson <cjwatson@debian.org> | 2003-09-17 00:32:19 +0000 |
commit | 22f9b945efa61bba12a4778b889df07cf851838a (patch) | |
tree | 77a3f749ea589c590db930cff12d804a4d7893b5 /ssh-keygen.0 | |
parent | 9d1471514608023cda6456f5a2e875cc5e4b9e77 (diff) | |
parent | 854156dd39acbde9b4a47ec0fc54a042ea7358e0 (diff) |
Import OpenSSH 3.7p1.
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1 | SSH-KEYGEN(1) BSD General Commands Manual SSH-KEYGEN(1) | ||
2 | |||
3 | NAME | ||
4 | ssh-keygen - authentication key generation, management and conversion | ||
5 | |||
6 | SYNOPSIS | ||
7 | ssh-keygen [-q] [-b bits] -t type [-N new_passphrase] [-C comment] | ||
8 | [-f output_keyfile] | ||
9 | ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-f keyfile] | ||
10 | ssh-keygen -i [-f input_keyfile] | ||
11 | ssh-keygen -e [-f input_keyfile] | ||
12 | ssh-keygen -y [-f input_keyfile] | ||
13 | ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile] | ||
14 | ssh-keygen -l [-f input_keyfile] | ||
15 | ssh-keygen -B [-f input_keyfile] | ||
16 | ssh-keygen -D reader | ||
17 | ssh-keygen -U reader [-f input_keyfile] | ||
18 | ssh-keygen -r hostname [-f input_keyfile] [-g] | ||
19 | ssh-keygen -G output_file [-b bits] [-M memory] [-S start_point] | ||
20 | ssh-keygen -T output_file -f input_file [-a num_trials] [-W generator] | ||
21 | |||
22 | DESCRIPTION | ||
23 | ssh-keygen generates, manages and converts authentication keys for | ||
24 | ssh(1). ssh-keygen can create RSA keys for use by SSH protocol version 1 | ||
25 | and RSA or DSA keys for use by SSH protocol version 2. The type of key | ||
26 | to be generated is specified with the -t option. | ||
27 | |||
28 | ssh-keygen is also used to generate groups for use in Diffie-Hellman | ||
29 | group exchange (DH-GEX). See the MODULI GENERATION section for details. | ||
30 | |||
31 | Normally each user wishing to use SSH with RSA or DSA authentication runs | ||
32 | this once to create the authentication key in $HOME/.ssh/identity, | ||
33 | $HOME/.ssh/id_dsa or $HOME/.ssh/id_rsa. Additionally, the system admin- | ||
34 | istrator may use this to generate host keys, as seen in /etc/rc. | ||
35 | |||
36 | Normally this program generates the key and asks for a file in which to | ||
37 | store the private key. The public key is stored in a file with the same | ||
38 | name but M-bM-^@M-^\.pubM-bM-^@M-^] appended. The program also asks for a passphrase. The | ||
39 | passphrase may be empty to indicate no passphrase (host keys must have an | ||
40 | empty passphrase), or it may be a string of arbitrary length. A | ||
41 | passphrase is similar to a password, except it can be a phrase with a | ||
42 | series of words, punctuation, numbers, whitespace, or any string of char- | ||
43 | acters you want. Good passphrases are 10-30 characters long, are not | ||
44 | simple sentences or otherwise easily guessable (English prose has only | ||
45 | 1-2 bits of entropy per character, and provides very bad passphrases), | ||
46 | and contain a mix of upper and lowercase letters, numbers, and non- | ||
47 | alphanumeric characters. The passphrase can be changed later by using | ||
48 | the -p option. | ||
49 | |||
50 | There is no way to recover a lost passphrase. If the passphrase is lost | ||
51 | or forgotten, a new key must be generated and copied to the corresponding | ||
52 | public key to other machines. | ||
53 | |||
54 | For RSA1 keys, there is also a comment field in the key file that is only | ||
55 | for convenience to the user to help identify the key. The comment can | ||
56 | tell what the key is for, or whatever is useful. The comment is initial- | ||
57 | ized to M-bM-^@M-^\user@hostM-bM-^@M-^] when the key is created, but can be changed using the | ||
58 | -c option. | ||
59 | |||
60 | After a key is generated, instructions below detail where the keys should | ||
61 | be placed to be activated. | ||
62 | |||
63 | The options are as follows: | ||
64 | |||
65 | -a trials | ||
66 | Specifies the number of primality tests to perform when screening | ||
67 | DH-GEX candidates using the -T command. | ||
68 | |||
69 | -b bits | ||
70 | Specifies the number of bits in the key to create. Minimum is | ||
71 | 512 bits. Generally, 1024 bits is considered sufficient. The | ||
72 | default is 1024 bits. | ||
73 | |||
74 | -c Requests changing the comment in the private and public key | ||
75 | files. This operation is only supported for RSA1 keys. The pro- | ||
76 | gram will prompt for the file containing the private keys, for | ||
77 | the passphrase if the key has one, and for the new comment. | ||
78 | |||
79 | -e This option will read a private or public OpenSSH key file and | ||
80 | print the key in a M-bM-^@M-^XSECSH Public Key File FormatM-bM-^@M-^Y to stdout. | ||
81 | This option allows exporting keys for use by several commercial | ||
82 | SSH implementations. | ||
83 | |||
84 | -g Use generic DNS resource record format. | ||
85 | |||
86 | -f filename | ||
87 | Specifies the filename of the key file. | ||
88 | |||
89 | -i This option will read an unencrypted private (or public) key file | ||
90 | in SSH2-compatible format and print an OpenSSH compatible private | ||
91 | (or public) key to stdout. ssh-keygen also reads the M-bM-^@M-^XSECSH | ||
92 | Public Key File FormatM-bM-^@M-^Y. This option allows importing keys from | ||
93 | several commercial SSH implementations. | ||
94 | |||
95 | -l Show fingerprint of specified public key file. Private RSA1 keys | ||
96 | are also supported. For RSA and DSA keys ssh-keygen tries to | ||
97 | find the matching public key file and prints its fingerprint. | ||
98 | |||
99 | -p Requests changing the passphrase of a private key file instead of | ||
100 | creating a new private key. The program will prompt for the file | ||
101 | containing the private key, for the old passphrase, and twice for | ||
102 | the new passphrase. | ||
103 | |||
104 | -q Silence ssh-keygen. Used by /etc/rc when creating a new key. | ||
105 | |||
106 | -y This option will read a private OpenSSH format file and print an | ||
107 | OpenSSH public key to stdout. | ||
108 | |||
109 | -t type | ||
110 | Specifies the type of the key to create. The possible values are | ||
111 | M-bM-^@M-^\rsa1M-bM-^@M-^] for protocol version 1 and M-bM-^@M-^\rsaM-bM-^@M-^] or M-bM-^@M-^\dsaM-bM-^@M-^] for protocol | ||
112 | version 2. | ||
113 | |||
114 | -B Show the bubblebabble digest of specified private or public key | ||
115 | file. | ||
116 | |||
117 | -C comment | ||
118 | Provides the new comment. | ||
119 | |||
120 | -D reader | ||
121 | Download the RSA public key stored in the smartcard in reader. | ||
122 | |||
123 | -G output_file | ||
124 | Generate candidate primes for DH-GEX. These primes must be | ||
125 | screened for safety (using the -T option) before use. | ||
126 | |||
127 | -M memory | ||
128 | Specify the amount of memory to use (in megabytes) when generat- | ||
129 | ing candidate moduli for DH-GEX. | ||
130 | |||
131 | -N new_passphrase | ||
132 | Provides the new passphrase. | ||
133 | |||
134 | -P passphrase | ||
135 | Provides the (old) passphrase. | ||
136 | |||
137 | -S start | ||
138 | Specify start point (in hex) when generating candidate moduli for | ||
139 | DH-GEX. | ||
140 | |||
141 | -T output_file | ||
142 | Test DH group exchange candidate primes (generated using the -G | ||
143 | option) for safety. | ||
144 | |||
145 | -W generator | ||
146 | Specify desired generator when testing candidate moduli for DH- | ||
147 | GEX. | ||
148 | |||
149 | -U reader | ||
150 | Upload an existing RSA private key into the smartcard in reader. | ||
151 | |||
152 | -r hostname | ||
153 | Print DNS resource record with the specified hostname. | ||
154 | |||
155 | MODULI GENERATION | ||
156 | ssh-keygen may be used to generate groups for the Diffie-Hellman Group | ||
157 | Exchange (DH-GEX) protocol. Generating these groups is a two-step pro- | ||
158 | cess: first, candidate primes are generated using a fast, but memory | ||
159 | intensive process. These candidate primes are then tested for suitabil- | ||
160 | ity (a CPU-intensive process). | ||
161 | |||
162 | Generation of primes is performed using the -G option. The desired | ||
163 | length of the primes may be specified by the -b option. For example: | ||
164 | |||
165 | ssh-keygen -G moduli-2048.candidates -b 2048 | ||
166 | |||
167 | By default, the search for primes begins at a random point in the desired | ||
168 | length range. This may be overridden using the -S option, which speci- | ||
169 | fies a different start point (in hex). | ||
170 | |||
171 | Once a set of candidates have been generated, they must be tested for | ||
172 | suitability. This may be performed using the -T option. In this mode | ||
173 | ssh-keygen will read candidates from standard input (or a file specified | ||
174 | using the -f option). For example: | ||
175 | |||
176 | ssh-keygen -T moduli-2048 -f moduli-2048.candidates | ||
177 | |||
178 | By default, each candidate will be subjected to 100 primality tests. | ||
179 | This may be overridden using the -a option. The DH generator value will | ||
180 | be chosen automatically for the prime under consideration. If a specific | ||
181 | generator is desired, it may be requested using the -W option. Valid | ||
182 | generator values are 2, 3 and 5. | ||
183 | |||
184 | Screened DH groups may be installed in /etc/moduli. It is important that | ||
185 | this file contains moduli of a range of bit lengths and that both ends of | ||
186 | a connection share common moduli. | ||
187 | |||
188 | FILES | ||
189 | $HOME/.ssh/identity | ||
190 | Contains the protocol version 1 RSA authentication identity of | ||
191 | the user. This file should not be readable by anyone but the | ||
192 | user. It is possible to specify a passphrase when generating the | ||
193 | key; that passphrase will be used to encrypt the private part of | ||
194 | this file using 3DES. This file is not automatically accessed by | ||
195 | ssh-keygen but it is offered as the default file for the private | ||
196 | key. ssh(1) will read this file when a login attempt is made. | ||
197 | |||
198 | $HOME/.ssh/identity.pub | ||
199 | Contains the protocol version 1 RSA public key for authentica- | ||
200 | tion. The contents of this file should be added to | ||
201 | $HOME/.ssh/authorized_keys on all machines where the user wishes | ||
202 | to log in using RSA authentication. There is no need to keep the | ||
203 | contents of this file secret. | ||
204 | |||
205 | $HOME/.ssh/id_dsa | ||
206 | Contains the protocol version 2 DSA authentication identity of | ||
207 | the user. This file should not be readable by anyone but the | ||
208 | user. It is possible to specify a passphrase when generating the | ||
209 | key; that passphrase will be used to encrypt the private part of | ||
210 | this file using 3DES. This file is not automatically accessed by | ||
211 | ssh-keygen but it is offered as the default file for the private | ||
212 | key. ssh(1) will read this file when a login attempt is made. | ||
213 | |||
214 | $HOME/.ssh/id_dsa.pub | ||
215 | Contains the protocol version 2 DSA public key for authentica- | ||
216 | tion. The contents of this file should be added to | ||
217 | $HOME/.ssh/authorized_keys on all machines where the user wishes | ||
218 | to log in using public key authentication. There is no need to | ||
219 | keep the contents of this file secret. | ||
220 | |||
221 | $HOME/.ssh/id_rsa | ||
222 | Contains the protocol version 2 RSA authentication identity of | ||
223 | the user. This file should not be readable by anyone but the | ||
224 | user. It is possible to specify a passphrase when generating the | ||
225 | key; that passphrase will be used to encrypt the private part of | ||
226 | this file using 3DES. This file is not automatically accessed by | ||
227 | ssh-keygen but it is offered as the default file for the private | ||
228 | key. ssh(1) will read this file when a login attempt is made. | ||
229 | |||
230 | $HOME/.ssh/id_rsa.pub | ||
231 | Contains the protocol version 2 RSA public key for authentica- | ||
232 | tion. The contents of this file should be added to | ||
233 | $HOME/.ssh/authorized_keys on all machines where the user wishes | ||
234 | to log in using public key authentication. There is no need to | ||
235 | keep the contents of this file secret. | ||
236 | |||
237 | /etc/moduli | ||
238 | Contains Diffie-Hellman groups used for DH-GEX. The file format | ||
239 | is described in moduli(5). | ||
240 | |||
241 | SEE ALSO | ||
242 | ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) | ||
243 | |||
244 | J. Galbraith and R. Thayer, SECSH Public Key File Format, draft-ietf- | ||
245 | secsh-publickeyfile-01.txt, March 2001, work in progress material. | ||
246 | |||
247 | AUTHORS | ||
248 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
249 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
250 | de Raadt and Dug Song removed many bugs, re-added newer features and cre- | ||
251 | ated OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
252 | versions 1.5 and 2.0. | ||
253 | |||
254 | BSD September 25, 1999 BSD | ||