| .\" $OpenBSD: ssh-keygen.1,v 1.44 2001/06/23 02:33:05 deraadt Exp $ |
| .\" |
| .\" -*- nroff -*- |
| .\" |
| .\" Author: Tatu Ylonen <ylo@cs.hut.fi> |
| .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| .\" All rights reserved |
| .\" |
| .\" As far as I am concerned, the code I have written for this software |
| .\" can be used freely for any purpose. Any derived versions of this |
| .\" software must be clearly marked as such, and if the derived work is |
| .\" incompatible with the protocol description in the RFC file, it must be |
| .\" called by a name other than "ssh" or "Secure Shell". |
| .\" |
| .\" |
| .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. |
| .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. |
| .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. |
| .\" |
| .\" Redistribution and use in source and binary forms, with or without |
| .\" modification, are permitted provided that the following conditions |
| .\" are met: |
| .\" 1. Redistributions of source code must retain the above copyright |
| .\" notice, this list of conditions and the following disclaimer. |
| .\" 2. Redistributions in binary form must reproduce the above copyright |
| .\" notice, this list of conditions and the following disclaimer in the |
| .\" documentation and/or other materials provided with the distribution. |
| .\" |
| .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| .\" |
| .Dd September 25, 1999 |
| .Dt SSH-KEYGEN 1 |
| .Os |
| .Sh NAME |
| .Nm ssh-keygen |
| .Nd authentication key generation, management and conversion |
| .Sh SYNOPSIS |
| .Nm ssh-keygen |
| .Op Fl q |
| .Op Fl b Ar bits |
| .Op Fl t Ar type |
| .Op Fl N Ar new_passphrase |
| .Op Fl C Ar comment |
| .Op Fl f Ar output_keyfile |
| .Nm ssh-keygen |
| .Fl p |
| .Op Fl P Ar old_passphrase |
| .Op Fl N Ar new_passphrase |
| .Op Fl f Ar keyfile |
| .Nm ssh-keygen |
| .Fl i |
| .Op Fl f Ar input_keyfile |
| .Nm ssh-keygen |
| .Fl e |
| .Op Fl f Ar input_keyfile |
| .Nm ssh-keygen |
| .Fl y |
| .Op Fl f Ar input_keyfile |
| .Nm ssh-keygen |
| .Fl c |
| .Op Fl P Ar passphrase |
| .Op Fl C Ar comment |
| .Op Fl f Ar keyfile |
| .Nm ssh-keygen |
| .Fl l |
| .Op Fl f Ar input_keyfile |
| .Nm ssh-keygen |
| .Fl B |
| .Op Fl f Ar input_keyfile |
| .Sh DESCRIPTION |
| .Nm |
| generates, manages and converts authentication keys for |
| .Xr ssh 1 . |
| .Nm |
| defaults to generating a RSA1 key for use by SSH protocol version 1. |
| specifying the |
| .Fl t |
| option allows you to create a key for use by SSH protocol version 2. |
| .Pp |
| Normally each user wishing to use SSH |
| with RSA or DSA authentication runs this once to create the authentication |
| key in |
| .Pa $HOME/.ssh/identity , |
| .Pa $HOME/.ssh/id_dsa |
| or |
| .Pa $HOME/.ssh/id_rsa . |
| Additionally, the system administrator may use this to generate host keys, |
| as seen in |
| .Pa /etc/rc . |
| .Pp |
| Normally 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 |
| .Dq .pub |
| appended. |
| The program also asks for a passphrase. |
| The passphrase may be empty to indicate no passphrase |
| (host keys must have an empty passphrase), or it may be a string of |
| arbitrary length. |
| Good passphrases are 10-30 characters long and are |
| not simple sentences or otherwise easily guessable (English |
| prose has only 1-2 bits of entropy per character, and provides very bad |
| passphrases). |
| The passphrase can be changed later by using the |
| .Fl p |
| option. |
| .Pp |
| There is no way to recover a lost passphrase. |
| If the passphrase is |
| lost or forgotten, you will have to generate a new key and copy the |
| corresponding public key to other machines. |
| .Pp |
| For RSA1 keys, |
| 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 |
| .Dq user@host |
| when the key is created, but can be changed using the |
| .Fl c |
| option. |
| .Pp |
| After a key is generated, instructions below detail where the keys |
| should be placed to be activated. |
| .Pp |
| The options are as follows: |
| .Bl -tag -width Ds |
| .It Fl b Ar bits |
| Specifies the number of bits in the key to create. |
| Minimum is 512 bits. |
| Generally 1024 bits is considered sufficient, and key sizes |
| above that no longer improve security but make things slower. |
| The default is 1024 bits. |
| .It Fl c |
| Requests changing the comment in the private and public key files. |
| The program will prompt for the file containing the private keys, for |
| the passphrase if the key has one, and for the new comment. |
| .It Fl e |
| This option will read a private or public OpenSSH key file and |
| print the key in a |
| .Sq SECSH Public Key File Format |
| to stdout. |
| This option allows exporting keys for use by several commercial |
| SSH implementations. |
| .It Fl f |
| Specifies the filename of the key file. |
| .It Fl i |
| This option will read an unencrypted private (or public) key file |
| in SSH2-compatible format and print an OpenSSH compatible private |
| (or public) key to stdout. |
| .Nm |
| also reads the |
| .Sq SECSH Public Key File Format . |
| This option allows importing keys from several commercial |
| SSH implementations. |
| .It Fl l |
| Show fingerprint of specified private or public key file. |
| .It Fl p |
| Requests changing the passphrase of a private key file instead of |
| creating a new private key. |
| The program will prompt for the file |
| containing the private key, for the old passphrase, and twice for the |
| new passphrase. |
| .It Fl q |
| Silence |
| .Nm ssh-keygen . |
| Used by |
| .Pa /etc/rc |
| when creating a new key. |
| .It Fl y |
| This option will read a private |
| OpenSSH format file and print an OpenSSH public key to stdout. |
| .It Fl t Ar type |
| Specifies the type of the key to create. |
| The possible values are |
| .Dq rsa1 |
| for protocol version 1 and |
| .Dq rsa |
| or |
| .Dq dsa |
| for protocol version 2. |
| The default is |
| .Dq rsa1 . |
| .It Fl B |
| Show the bubblebabble digest of specified private or public key file. |
| .It Fl C Ar comment |
| Provides the new comment. |
| .It Fl N Ar new_passphrase |
| Provides the new passphrase. |
| .It Fl P Ar passphrase |
| Provides the (old) passphrase. |
| .El |
| .Sh FILES |
| .Bl -tag -width Ds |
| .It Pa $HOME/.ssh/identity |
| Contains the protocol version 1 RSA authentication identity of the user. |
| This file should not be readable by anyone but the user. |
| It is possible to |
| specify a passphrase when generating the key; that passphrase will be |
| used to encrypt the private part of this file using 3DES. |
| This file is not automatically accessed by |
| .Nm |
| but it is offered as the default file for the private key. |
| .Xr sshd 8 |
| will read this file when a login attempt is made. |
| .It Pa $HOME/.ssh/identity.pub |
| Contains the protocol version 1 RSA public key for authentication. |
| The contents of this file should be added to |
| .Pa $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. |
| .It Pa $HOME/.ssh/id_dsa |
| Contains the protocol version 2 DSA authentication identity of the user. |
| This file should not be readable by anyone but the user. |
| It is possible to |
| specify a passphrase when generating the key; that passphrase will be |
| used to encrypt the private part of this file using 3DES. |
| This file is not automatically accessed by |
| .Nm |
| but it is offered as the default file for the private key. |
| .Xr sshd 8 |
| will read this file when a login attempt is made. |
| .It Pa $HOME/.ssh/id_dsa.pub |
| Contains the protocol version 2 DSA public key for authentication. |
| The contents of this file should be added to |
| .Pa $HOME/.ssh/authorized_keys |
| on all machines |
| where you wish to log in using public key authentication. |
| There is no need to keep the contents of this file secret. |
| .It Pa $HOME/.ssh/id_rsa |
| Contains the protocol version 2 RSA authentication identity of the user. |
| This file should not be readable by anyone but the user. |
| It is possible to |
| specify a passphrase when generating the key; that passphrase will be |
| used to encrypt the private part of this file using 3DES. |
| This file is not automatically accessed by |
| .Nm |
| but it is offered as the default file for the private key. |
| .Xr sshd 8 |
| will read this file when a login attempt is made. |
| .It Pa $HOME/.ssh/id_rsa.pub |
| Contains the protocol version 2 RSA public key for authentication. |
| The contents of this file should be added to |
| .Pa $HOME/.ssh/authorized_keys |
| on all machines |
| where you wish to log in using public key authentication. |
| There is no need to keep the contents of this file secret. |
| .El |
| .Sh AUTHORS |
| OpenSSH is a derivative of the original and free |
| ssh 1.2.12 release by Tatu Ylonen. |
| Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, |
| Theo de Raadt and Dug Song |
| removed many bugs, re-added newer features and |
| created OpenSSH. |
| Markus Friedl contributed the support for SSH |
| protocol versions 1.5 and 2.0. |
| .Sh SEE ALSO |
| .Xr ssh 1 , |
| .Xr ssh-add 1 , |
| .Xr ssh-agent 1 , |
| .Xr sshd 8 |
| .Rs |
| .%A J. Galbraith and R. Thayer |
| .%T "SECSH Public Key File Format" |
| .%N draft-ietf-secsh-publickeyfile-01.txt |
| .%D March 2001 |
| .%O work in progress material |
| .Re |