5 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
7 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 .\" All rights reserved
10 .\" Created: Sat Apr 22 23:55:14 1995 ylo
14 .Dd September 25, 1999
19 .Nd authentication key generation
24 .Op Fl N Ar new_passphrase
29 .Op Fl P Ar old_passphrase
30 .Op Fl N Ar new_passphrase
34 .Op Fl P Ar passphrase
44 generates and manages authentication keys for
46 Normally each user wishing to use SSH
47 with RSA authentication runs this once to create the authentication
49 .Pa $HOME/.ssh/identity .
50 Additionally, the system administrator may use this to generate host keys.
52 Normally this program generates the key and asks for a file in which
53 to store the private key.
54 The public key is stored in a file with the same name but
57 The program also asks for a passphrase.
58 The passphrase may be empty to indicate no passphrase
59 (host keys must have empty passphrase), or it may be a string of
61 Good passphrases are 10-30 characters long and are
62 not simple sentences or otherwise easily guessable (English
63 prose has only 1-2 bits of entropy per word, and provides very bad
65 The passphrase can be changed later by using the
69 There is no way to recover a lost passphrase.
71 lost or forgotten, you will have to generate a new key and copy the
72 corresponding public key to other machines.
74 There is also a comment field in the key file that is only for
75 convenience to the user to help identify the key.
76 The comment can tell what the key is for, or whatever is useful.
77 The comment is initialized to
79 when the key is created, but can be changed using the
83 The options are as follows:
86 Specifies the number of bits in the key to create.
88 Generally 1024 bits is considered sufficient, and key sizes
89 above that no longer improve security but make things slower.
90 The default is 1024 bits.
92 Requests changing the comment in the private and public key files.
93 The program will prompt for the file containing the private keys, for
94 passphrase if the key has one, and for the new comment.
96 Specifies the filename of the key file.
98 Show fingerprint of specified private or public key file.
100 Requests changing the passphrase of a private key file instead of
101 creating a new private key.
102 The program will prompt for the file
103 containing the private key, for the old passphrase, and twice for the
110 when creating a new key.
112 Provides the new comment.
113 .It Fl N Ar new_passphrase
114 Provides the new passphrase.
115 .It Fl P Ar passphrase
116 Provides the (old) passphrase.
118 If RSA support is functional, immediately exits with code 0. If RSA
119 support is not functional, exits with code 1. This flag will be
120 removed once the RSA patent expires.
124 .It Pa $HOME/.ssh/identity
125 Contains the RSA authentication identity of the user.
126 This file should not be readable by anyone but the user.
128 specify a passphrase when generating the key; that passphrase will be
129 used to encrypt the private part of this file using 3DES.
130 This file is not automatically accessed by
132 but it is offered as the default file for the private key.
133 .It Pa $HOME/.ssh/identity.pub
134 Contains the public key for authentication.
135 The contents of this file should be added to
136 .Pa $HOME/.ssh/authorized_keys
138 where you wish to log in using RSA authentication.
139 There is no need to keep the contents of this file secret.
141 Tatu Ylonen <ylo@cs.hut.fi>
144 is a derivative of the original (free) ssh 1.2.12 release, but with bugs
145 removed and newer features re-added.
146 Rapidly after the 1.2.12 release,
147 newer versions bore successively more restrictive licenses.
148 This version of OpenSSH
151 has all components of a restrictive nature (i.e., patents)
152 directly removed from the source code; any licensed or patented components
156 has been updated to support ssh protocol 1.5.
158 contains added support for
160 authentication and ticket passing.
162 supports one-time password authentication with