ssh-keygen.1 - security/openssh-library - Rivoreo Source Code Repositories

 .\"	$OpenBSD: ssh-keygen.1,v 1.42 2001/06/03 19:36:44 markus 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
 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 .\" (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_keys2
 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_keys2
 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
 .%A R. Thayer
 .%T "SECSH Public Key File Format"
 .%N draft-ietf-secsh-publickeyfile-01.txt
 .%D March 2001
 .%O work in progress material
 .Re
	.\" $OpenBSD: ssh-keygen.1,v 1.42 2001/06/03 19:36:44 markus 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
	.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	.\" (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_keys2
	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_keys2
	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
	.%A R. Thayer
	.%T "SECSH Public Key File Format"
	.%N draft-ietf-secsh-publickeyfile-01.txt
	.%D March 2001
	.%O work in progress material
	.Re