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 ] [ -q ]
14 \e bb iiiiiiiiiii bb bb
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 Note that generating a key requires random data (from
41 \c{/dev/random}), which can cause \c{puttygen} to pause, possibly for
42 some time if your system does not have much randomness available.
44 The options to control this phase are:
48 \dd Specify a private key file to be loaded. This private key file can
49 be in the (de facto standard) SSH-1 key format, or in PuTTY's SSH-2
50 key format, or in either of the SSH-2 private key formats used by
51 OpenSSH and ssh.com's implementation.
53 \dt \cw{\-t} \e{keytype}
55 \dd Specify a type of key to generate. The acceptable values here are
56 \c{rsa}, \c{dsa}, \c{ecdsa}, and \c{ed25519} (to generate SSH-2 keys),
57 and \c{rsa1} (to generate SSH-1 keys).
61 \dd Specify the size of the key to generate, in bits. Default is 2048.
65 \dd Suppress the progress display when generating a new key.
67 In the second phase, \c{puttygen} optionally alters properties of
68 the key it has loaded or generated. The options to control this are:
70 \dt \cw{\-C} \e{new\-comment}
72 \dd Specify a comment string to describe the key. This comment string
73 will be used by PuTTY to identify the key to you (when asking you to
74 enter the passphrase, for example, so that you know which passphrase
79 \dd Indicate that you want to change the key's passphrase. This is
80 automatic when you are generating a new key, but not when you are
81 modifying an existing key.
83 In the third phase, \c{puttygen} saves the key or information
84 about it. The options to control this are:
86 \dt \cw{\-O} \e{output\-type}
88 \dd Specify the type of output you want \c{puttygen} to produce.
89 Acceptable options are:
95 \dd Save the private key in a format usable by PuTTY. This will either
96 be the standard SSH-1 key format, or PuTTY's own SSH-2 key format.
100 \dd Save the public key only. For SSH-1 keys, the standard public key
101 format will be used (\q{\cw{1024 37 5698745}...}). For SSH-2 keys, the
102 public key will be output in the format specified by RFC 4716,
103 which is a multi-line text file beginning with the line
104 \q{\cw{---- BEGIN SSH2 PUBLIC KEY ----}}.
106 \dt \cw{public-openssh}
108 \dd Save the public key only, in a format usable by OpenSSH. For SSH-1
109 keys, this output format behaves identically to \c{public}. For
110 SSH-2 keys, the public key will be output in the OpenSSH format,
111 which is a single line (\q{\cw{ssh-rsa AAAAB3NzaC1yc2}...}).
115 \dd Print the fingerprint of the public key. All fingerprinting
116 algorithms are believed compatible with OpenSSH.
118 \dt \cw{private-openssh}
120 \dd Save an SSH-2 private key in OpenSSH's format, using the oldest
121 format available to maximise backward compatibility. This option is not
122 permitted for SSH-1 keys.
124 \dt \cw{private-openssh-new}
126 \dd As \c{private-openssh}, except that it forces the use of OpenSSH's
127 newer format even for RSA, DSA, and ECDSA keys.
129 \dt \cw{private-sshcom}
131 \dd Save an SSH-2 private key in ssh.com's format. This option is not
132 permitted for SSH-1 keys.
134 If no output type is specified, the default is \c{private}.
138 \dt \cw{\-o} \e{output\-file}
140 \dd Specify the file where \c{puttygen} should write its output. If
141 this option is not specified, \c{puttygen} will assume you want to
142 overwrite the original file if the input and output file types are
143 the same (changing a comment or passphrase), and will assume you
144 want to output to stdout if you are asking for a public key or
145 fingerprint. Otherwise, the \c{\-o} option is required.
149 \dd Synonym for \q{\cw{-O fingerprint}}.
153 \dd Synonym for \q{\cw{-O public-openssh}}.
157 \dd Synonym for \q{\cw{-O public}}.
159 The following options do not run PuTTYgen as normal, but print
160 informational messages and then quit:
162 \dt \cw{\-h}, \cw{\-\-help}
164 \dd Display a message summarizing the available options.
166 \dt \cw{\-V}, \cw{\-\-version}
168 \dd Display the version of PuTTYgen.
172 \dd Display the fingerprints of the PuTTY PGP Master Keys, to aid
173 in verifying new files released by the PuTTY team.
175 \S{puttygen-manpage-examples} EXAMPLES
177 To generate an SSH-2 RSA key pair and save it in PuTTY's own format
178 (you will be prompted for the passphrase):
180 \c puttygen -t rsa -C "my home key" -o mykey.ppk
182 To generate a larger (4096-bit) key:
184 \c puttygen -t rsa -b 4096 -C "my home key" -o mykey.ppk
186 To change the passphrase on a key (you will be prompted for the old
187 and new passphrases):
189 \c puttygen -P mykey.ppk
191 To change the comment on a key:
193 \c puttygen -C "new comment" mykey.ppk
195 To convert a key into OpenSSH's private key format:
197 \c puttygen mykey.ppk -O private-openssh -o my-openssh-key
199 To convert a key \e{from} another format (\c{puttygen} will
200 automatically detect the input key type):
202 \c puttygen my-ssh.com-key -o mykey.ppk
204 To display the fingerprint of a key (some key types require a
205 passphrase to extract even this much information):
207 \c puttygen -l mykey.ppk
209 To add the OpenSSH-format public half of a key to your authorised
212 \c puttygen -L mykey.ppk >> $HOME/.ssh/authorized_keys
214 \S{puttygen-manpage-bugs} BUGS
216 There's currently no way to supply passphrases in batch mode, or
217 even just to specify that you don't want a passphrase at all.