ssh-keygen(1) User Commands ssh-keygen(1)
NAME
ssh-keygen - authentication key generation
SYNOPSIS
ssh-keygen [-q] [-b bits ] -t type [-N new_passphrase] [-C comment] [-f output_keyfile]
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]
DESCRIPTION
The ssh-keygen utility generates, manages, and converts authentication keys for ssh(1). ssh-keygen can create RSA keys for use by SSH pro-
tocol 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/iden-
tity, $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
characters. (English prose has only 1-2 bits of entropy per word and provides 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 corre-
sponding 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 -c option.
After a key is generated, instructions below detail where to place the keys to activate them.
OPTIONS
The following options are supported:
-b bits Specifies the number of bits in the key to create. The minimum number is 512 bits. Generally, 1024 bits is consid-
ered 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 comment.
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 implementations.
-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 com-
patible private (or public) key to stdout. ssh-keygen also reads the "SECSH" Public Key File Format. This option
allows importing keys from several other SSH implementations.
-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.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
1 An error occurred.
FILES
$HOME/.ssh/identity
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.
$HOME/.ssh/identity.pub
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.
$HOME/.ssh/id_dsa
$HOME/.ssh/id_rsa
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 generating 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.
$HOME/.ssh/id_dsa.pub
$HOME/.ssh/id_rsa.pub
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.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWsshcu |
+-----------------------------+-----------------------------+
|Interface Stability |Evolving |
+-----------------------------+-----------------------------+
SEE ALSO
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
location.
SunOS 5.10 9 Nov 2004 ssh-keygen(1)