1 \cfg{man-identity}{puttygen}{1}{2004-03-24}{PuTTY tool suite}{PuTTY tool suite}
3 \H{puttygen-manpage} Man page for PuTTYgen
5 \S{puttygen-manpage-name} NAME
7 \cw{puttygen} - public-key generator for the PuTTY tools
9 \S{puttygen-manpage-synopsis} SYNOPSIS
11 \c puttygen ( keyfile | -t keytype [ -b bits ] )
12 \e bbbbbbbb iiiiiii bb iiiiiii bb iiii
13 \c [ -C new-comment ] [ -P ]
15 \c [ -O output-type | -l | -L | -p ]
16 \e bb iiiiiiiiiii bb bb bb
20 \S{puttygen-manpage-description} DESCRIPTION
22 \c{puttygen} is a tool to generate and manipulate SSH public and
23 private key pairs. It is part of the PuTTY suite, although it can
24 also interoperate with the private key formats used by some other
27 When you run \c{puttygen}, it does three things. Firstly, it either
28 loads an existing key file (if you specified \e{keyfile}), or
29 generates a new key (if you specified \e{keytype}). Then, it
30 optionally makes modifications to the key (changing the comment
31 and/or the passphrase); finally, it outputs the key, or some
32 information about the key, to a file.
34 All three of these phases are controlled by the options described in
35 the following section.
37 \S{puttygen-manpage-options} OPTIONS
39 In the first phase, \c{puttygen} either loads or generates a key.
40 The options to control this are:
44 \dd Specify a private key file to be loaded. This private key file can
45 be in the (de facto standard) SSH-1 key format, or in PuTTY's SSH-2
46 key format, or in either of the SSH-2 private key formats used by
47 OpenSSH and ssh.com's implementation.
49 \dt \cw{\-t} \e{keytype}
51 \dd Specify a type of key to generate. The acceptable values here are
52 \c{rsa} and \c{dsa} (to generate SSH-2 keys), and \c{rsa1} (to
57 \dd Specify the size of the key to generate, in bits. Default is 1024.
59 In the second phase, \c{puttygen} optionally alters properties of
60 the key it has loaded or generated. The options to control this are:
62 \dt \cw{\-C} \e{new\-comment}
64 \dd Specify a comment string to describe the key. This comment string
65 will be used by PuTTY to identify the key to you (when asking you to
66 enter the passphrase, for example, so that you know which passphrase
71 \dd Indicate that you want to change the key's passphrase. This is
72 automatic when you are generating a new key, but not when you are
73 modifying an existing key.
75 In the third phase, \c{puttygen} saves the key or information
76 about it. The options to control this are:
78 \dt \cw{\-O} \e{output\-type}
80 \dd Specify the type of output you want \c{puttygen} to produce.
81 Acceptable options are:
87 \dd Save the private key in a format usable by PuTTY. This will either
88 be the standard SSH-1 key format, or PuTTY's own SSH-2 key format.
92 \dd Save the public key only. For SSH-1 keys, the standard public key
93 format will be used (\q{\cw{1024 37 5698745}...}). For SSH-2 keys, the
94 public key will be output in the format specified in the IETF
95 drafts, which is a multi-line text file beginning with the line
96 \q{\cw{---- BEGIN SSH2 PUBLIC KEY ----}}.
98 \dt \cw{public-openssh}
100 \dd Save the public key only, in a format usable by OpenSSH. For SSH-1
101 keys, this output format behaves identically to \c{public}. For
102 SSH-2 keys, the public key will be output in the OpenSSH format,
103 which is a single line (\q{\cw{ssh-rsa AAAAB3NzaC1yc2}...}).
107 \dd Print the fingerprint of the public key. All fingerprinting
108 algorithms are believed compatible with OpenSSH.
110 \dt \cw{private-openssh}
112 \dd Save an SSH-2 private key in OpenSSH's format. This option is not
113 permitted for SSH-1 keys.
115 \dt \cw{private-sshcom}
117 \dd Save an SSH-2 private key in ssh.com's format. This option is not
118 permitted for SSH-1 keys.
120 If no output type is specified, the default is \c{private}.
124 \dt \cw{\-o} \e{output\-file}
126 \dd Specify the file where \c{puttygen} should write its output. If
127 this option is not specified, \c{puttygen} will assume you want to
128 overwrite the original file if the input and output file types are
129 the same (changing a comment or passphrase), and will assume you
130 want to output to stdout if you are asking for a public key or
131 fingerprint. Otherwise, the \c{\-o} option is required.
135 \dd Synonym for \q{\cw{-O fingerprint}}.
139 \dd Synonym for \q{\cw{-O public-openssh}}.
143 \dd Synonym for \q{\cw{-O public}}.
145 \S{puttygen-manpage-examples} EXAMPLES
147 To generate an SSH-2 RSA key pair and save it in PuTTY's own format
148 (you will be prompted for the passphrase):
150 \c puttygen -t rsa -C "my home key" -o mykey.ppk
152 To generate a larger (2048-bit) key:
154 \c puttygen -t rsa -b 2048 -C "my home key" -o mykey.ppk
156 To change the passphrase on a key (you will be prompted for the old
157 and new passphrases):
159 \c puttygen -P mykey.ppk
161 To change the comment on a key:
163 \c puttygen -C "new comment" mykey.ppk
165 To convert a key into OpenSSH's private key format:
167 \c puttygen mykey.ppk -O private-openssh -o my-openssh-key
169 To convert a key \e{from} another format (\c{puttygen} will
170 automatically detect the input key type):
172 \c puttygen my-ssh.com-key -o mykey.ppk
174 To display the fingerprint of a key (some key types require a
175 passphrase to extract even this much information):
177 \c puttygen -l mykey.ppk
179 To add the OpenSSH-format public half of a key to your authorised
182 \c puttygen -L mykey.ppk >> $HOME/.ssh/authorized_keys
184 \S{puttygen-manpage-bugs} BUGS
186 There's currently no way to supply passphrases in batch mode, or
187 even just to specify that you don't want a passphrase at all.