ssh-keygen(1) User Commands ssh-keygen(1)
ssh-keygen - authentication key generation
ssh-keygen [-q] [-b bits ] -t type [-N new_passphrase] [-C comment] [-f
ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-f keyfile]
ssh-keygen -i [-f input_keyfile]
ssh-keygen -e [-f input_keyfile]
ssh-keygen -y [-f input_keyfile]
ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile]
ssh-keygen -l [-f input_keyfile]
ssh-keygen -B [-f input_keyfile]
The ssh-keygen utility generates, manages, and converts authentication
keys for ssh(1). ssh-keygen can create RSA keys for use by SSH protocol
version 1 and RSA or DSA keys for use by SSH protocol version 2. The
type of key to be generated is specified with the -t option.
Normally, each user wishing to use SSH with RSA or DSA authentication
runs this once to create the authentication key in $HOME/.ssh/identity,
$HOME/.ssh/id_dsa, or $HOME/.ssh/id_rsa. The system administrator can
also use this to generate host keys..
Ordinarily, this program generates the key and asks for a file in which
to store the private key. The public key is stored in a file with the
same name but with the ``.pub'' extension appended. The program also
asks for a passphrase. The passphrase can be empty to indicate no
passphrase (host keys must have empty passphrases), or it can be a
string of arbitrary length. Good passphrases are 10-30 characters long,
are not simple sentences or otherwise easy to guess, and contain a mix
of uppercase and lowercase letters, numbers, and non-alphanumeric char-
acters. (English prose has only 1-2 bits of entropy per word and pro-
vides very poor passphrases.)
The passphrase can be changed later by using the -p option.
There is no way to recover a lost passphrase. If the passphrase is lost
or forgotten, you have to generate a new key and copy the corresponding
public key to other machines.
For RSA, there is also a comment field in the key file that is only for
convenience to the user to help identify the key. The comment can tell
what the key is for, or whatever is useful. The comment is initialized
to ``user@host'' when the key is created, but can be changed using the
After a key is generated, instructions below detail where to place the
keys to activate them.
The following options are supported:
-b bits Specifies the number of bits in the key to cre-
ate. The minimum number is 512 bits. Generally,
1024 bits is considered sufficient. Key sizes
above that no longer improve security but make
things slower. The default is 1024 bits.
-B Shows the bubblebabble digest of the specified
private or public key file.
-c Requests changing the comment in the private
and public key files. The program prompts for
the file containing the private keys, for the
passphrase if the key has one, and for the new
This option only applies to rsa1 (SSHv1) keys.
-C comment Provides the new comment.
-e This option reads a private or public OpenSSH
key file and prints the key in a "SECSH" Public
Key File Format to stdout. This option allows
exporting keys for use by several other SSH
-f Specifies the filename of the key file.
-i This option reads an unencrypted private (or
public) key file in SSH2-compatible format and
prints an OpenSSH compatible private (or pub-
lic) key to stdout. ssh-keygen also reads the
"SECSH" Public Key File Format. This option
allows importing keys from several other SSH
-l Shows the fingerprint of the specified private
or public key file.
-N new_passphrase Provides the new passphrase.
-p Requests changing the passphrase of a private
key file instead of creating a new private key.
The program prompts for the file containing the
private key, for the old passphrase, and
prompts twice for the new passphrase.
-P passphrase Provides the (old) passphrase.
-q Silences ssh-keygen.
-t type Specifies the algorithm used for the key, where
type is one of rsa, dsa, and rsa1. Type rsa1 is
used only for the SSHv1 protocol.
-x Obsolete. Replaced by the -e option.
-X Obsolete. Replaced by the -i option.
-y This option reads a private OpenSSH format file
and prints an OpenSSH public key to stdout.
The following exit values are returned:
0 Successful completion.
1 An error occurred.
This file contains the RSA private key for the SSHv1 protocol. This
file should not be readable by anyone but the user. It is possible
to specify a passphrase when generating the key; that passphrase is
used to encrypt the private part of this file using 3DES. This file
is not automatically accessed by ssh-keygen, but it is offered as
the default file for the private key. sshd(1M) reads this file when
a login attempt is made.
This file contains the RSA public key for the SSHv1 protocol. The
contents of this file should be added to $HOME/.ssh/authorized_keys
on all machines where you wish to log in using RSA authentication.
There is no need to keep the contents of this file secret.
These files contain, respectively, the DSA or RSA private key for
the SSHv2 protocol. These files should not be readable by anyone
but the user. It is possible to specify a passphrase when generat-
ing the key; that passphrase is used to encrypt the private part of
the file using 3DES. Neither of these files is automatically
accessed by ssh-keygen but is offered as the default file for the
private key. sshd(1M) reads this file when a login attempt is made.
These files contain, respectively, the DSA or RSA public key for
the SSHv2 protocol. The contents of these files should be added,
respectively, to $HOME/.ssh/authorized_keys on all machines where
you wish to log in using DSA or RSA authentication. There is no
need to keep the contents of these files secret.
See attributes(5) for descriptions of the following attributes:
tab() allbox; cw(2.750000i)| cw(2.750000i) lw(2.750000i)|
lw(2.750000i). ATTRIBUTE TYPEATTRIBUTE VALUE AvailabilitySUNWsshcu
ssh(1), ssh-add(1), ssh-agent(1), sshd(1M), attributes(5)
To view license terms, attribution, and copyright for OpenSSH, the
default path is /var/sadm/pkg/SUNWsshdr/install/copyright. If the
Solaris operating environment has been installed anywhere other than
the default, modify the given path to access the file at the installed
SunOS 5.10 9 Nov 2004 ssh-keygen(1)