src/netpgpkeys/netpgpkeys.1

.\" $NetBSD: netpgpkeys.1,v 1.17 2010/11/04 09:30:33 wiz Exp $
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.\" This manual page is derived from software contributed to
.\" The NetBSD Foundation by Alistair Crooks (agc@NetBSD.org).
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.Dd November 4, 2010
.Dt NETPGPKEYS 1
.Os
.Sh NAME
.Nm netpgpkeys
.Nd PGP key management utility
.Sh SYNOPSIS
.Nm
.Fl Fl export\-key
.Op options
.Ar file ...
.Nm
.Fl Fl find\-key
.Op options
.Ar file ...
.Nm
.Fl Fl generate\-key
.Op options
.Ar file ...
.Nm
.Fl Fl import\-key
.Op options
.Ar file ...
.Nm
.Fl Fl list\-keys
.Op options
.Ar file ...
.Nm
.Fl Fl list\-sigs
.Op options
.Ar file ...
.Nm
.Fl Fl version
.Nm
.Op Fl Vgls
.Op Fl olong-option Ns = Ns value
.Ar file ...
.Pp
where the long options for all commands are:
.Pp
.Op Fl Fl cipher Ns = Ns Ar cipher\-algorithm
.br
.Op Fl Fl coredumps
.br
.Op Fl Fl hash Ns = Ns Ar hash\-algorithm
.br
.Op Fl Fl homedir Ns = Ns Ar home\-directory
.br
.Op Fl Fl keyring Ns = Ns Ar keyring
.br
.Op Fl Fl ssh-keys
.br
.Op Fl Fl userid Ns = Ns Ar userid
.br
.Op Fl Fl verbose
.Sh DESCRIPTION
At the present time, the
.Nm
utility is still under development.
Whilst the signing and verification, encryption and
decryption parts of
.Xr netpgp 1
are considered mature,
.Nm
needs more work.
Other key management utilities should be used in preference
to this one.
.Pp
The
.Nm
command is used for all forms of PGP key management,
from generation of new keys to propagation of public
keys to key servers, and import of new public
keys from other identities.
.Pp
The
.Xr netpgp 1
utility should be used for file management and transformation - encryption,
decryption,
signing and verification of files.
.Pp
For signing and encryption, a unique identity is needed.
This identity is made up of a private and public key.
The public key part is made available and known to everyone.
The private key is kept secret, and known only to the user
who created the identity.
The secret key is protected with a passphrase.
.Pp
In rough terms, a digital signature
is a digest of a file's contents,
encrypted with the user's private key.
Since together, the private and public keys identify the user
uniquely, the signature can be used to identify the exact version
of the file, and any changes made to the file will mean that the
signature no longer matches.
.Pp
As a corollary, the file can be transformed using a user's public key,
into text such that the contents can only be viewed by someone
with the corresponding private key.
This is called encryption.
.Pp
The
.Nm
utility can be used to generate a new key-pair for a user.
As mentioned before,
this key is in two parts, the public key (which is known
by other people) and the private key.
.Pp
The other use of
.Nm
is to maintain keyrings.
Key and keyring management commands available are:
.Fl Fl export\-key ,
.Fl Fl find\-key ,
.Fl Fl generate\-key ,
.Fl Fl import\-key ,
and
.Fl Fl list\-keys .
Keyrings are collections of public keys belonging to other users.
By using other means of identification, it is possible to establish
the bona fides of other users.
Once trust has been established, the public key of the other
user will be signed.
The other user's public key can be added to our keyring.
The other user will add our public key to their keyring.
.Pp
Keys can be listed, exported (i.e. made available to others),
and imported (i.e. users who have signed our public key).
.Pp
Key and keyring management can be done with the
following commands:
.Bl -tag -width Ar
.It Fl Fl export\-key
Display the current public key in a format suitable for export.
This can be used to place the keyring on one of the
public key servers, for example.
.It Fl Fl find\-key
Find the appropriate public key from the current keyring.
If no keyring is provided, the user's public keyring is used.
.It Fl Fl generate\-key
This command is used to generate a new public and private key pair.
If provided on the command line, the argument will be given to the
key generation routine to be used as the identity of the key.
This is usually the email address and full name, but can be
any identification token.
The newly-generated keys are placed in a sub-directory of the
.Dq home directory
which is created at key generation time.
At present, only RSA keys can be generated.
The hash algorithm and keysize can be specified on the command
line.
.It Fl Fl import\-key
Import a public key as retrieved from one of the public key servers.
This is in the form of a file which has previously been
retrieved from elsewhere.
.It Fl Fl list\-keys
List all the public keys in the current keyring.
If no keyring is provided, the user's public keyring is used.
.It Fl Fl list\-sigs
List all the public keys in the current keyring, along with
the sub-key signatures which provide the key with trust.
If no keyring is provided, the user's public keyring is used.
.It Fl Fl version
Print the version information from the
.Xr libnetpgp 3
library.
.El
.Pp
In addition to one of the preceding commands, a number of qualifiers
or options may be given.
.Bl -tag -width Ar
.It Fl Fl cipher Ar cipher\-algorithm
Specify the cipher to be used for symmetric encryption.
The default cipher is "CAST5".
.It Fl Fl hash Ar hash\-algorithm
Specify the hash algorithm which is used during fingerprint calculation.
For reference, at the present time,
.Xr ssh-keygen 1
uses
.Dq MD5
for its fingerprint values.
.It Fl Fl homedir Ar home\-directory
Keyrings are normally located, for historical reasons, within
the user's home directory in a subdirectory called
.Dq Pa .gnupg
and this option specifies an alternative location in which to
find that sub-directory.
.It Fl Fl keyring Ar keyring
This option specifies an alternative keyring to be used.
All keyring operations will be relative to this alternative keyring.
.It Fl Fl numbits Ar numbits
specifies the number of bits to be used when generating a key.
The default number of bits is 2048.
This is considered the absolute
minimum which should be chosen at the time of writing (2009).
Due to advances in computing power every year, this number should
be reviewed, and increased when it becomes easier to factor 2048
bit numbers.
.It Fl Fl userid Ar userid
This option specifies the user identity to be used for all operations.
This identity can either be in the form of the full name, or as an
email address.
Care should be exercised with these ways of specifying the user identity,
since the
.Nm
utility has no way of verifying that an email address is valid, or
that a key belongs to a certain individual.
The trust for a signed key is given by the other signers of that key.
The 16 hexadecimal digit user identity should be used when specifying
user identities - email addresses and names are provided as aliases.
.It Fl Fl pass\-fd Ns = Ns Ar fd
This option is intended for the use of external programs which may
like to use the
.Xr libnetpgp 3
library through the
.Nm
interface, but have their own ways of retrieving and caching
the passphrase for the secret key.
In this case, the
.Nm
utility will read a line of text from the file descriptor
passed to it in the command line argument, rather than
using its own methods of retrieving the passphrase from
the user.
.It Fl Fl verbose
This option can be used to view information during
the process of the
.Nm
requests.
.It Fl Fl ssh-keys
specifies that the public and private keys should be taken
from the
.Xr ssh 1
host key files, usually found in
.Pa /etc/ssh/ssh_host_rsa_key
and
.Pa /etc/ssh/ssh_host_rsa_key.pub
for the private and public host keys.
.It Fl Fl coredumps
in normal processing,
if an error occurs, the contents of memory are saved to disk, and can
be read using tools to analyse behaviour.
Unfortunately this can disclose information to people viewing
the core dump, such as secret keys, and passphrases protecting
those keys.
In normal operation,
.Nm
will turn off the ability to save core dumps on persistent storage,
but selecting this option will allow core dumps to be written to disk.
This option should be used wisely, and any core dumps should
be deleted in a secure manner when no longer needed.
.El
.Pp
It is often useful to be able to refer to another user's identity by
using their
.Nm
.Dq fingerprint .
This can be found in the output from normal
.Fl Fl list\-keys
and
.Fl Fl list\-sigs
commands.
.Sh PASS PHRASES
The pass phrase cannot be changed by
.Nm
once it has been chosen, and will
be used for the life of the key, so a wise choice is advised.
The pass phrase should not be an easily guessable word or phrase,
or related to information that can be gained through
.Dq social engineering
using search engines, or other public information retrieval methods.
.Pp
.Xr getpass 3
will be used to obtain the pass phrase from the user if it is
needed,
such as during signing or encryption, or key generation,
so that any secret information cannot be viewed by other users
using the
.Xr ps 1
or
.Xr top 1
commands, or by looking over the shoulder at the screen.
.Pp
Since the public and private key pair can be used to verify
a person's identity, and since identity theft can have
far-reaching consequences, users are strongly encouraged to
enter their pass phrases only when prompted by the application.
.Sh EXIT STATUS
The
.Nm
utility will return 0 for success,
1 if the file's signature does not match what was expected,
or 2 if any other error occurs.
.Sh EXAMPLES
.Bd -literal
% netpgpkeys --ssh-keys --sshkeyfile=/etc/ssh/ssh_host_rsa_key.pub --list-keys --hash=md5
1 key
pub 1024/RSA (Encrypt or Sign) fcdd1c608bef4c4b 2008-08-11
Key fingerprint: e935 902d ebf1 76ba fcdd 1c60 8bef 4c4b
uid              osx-vm1.crowthorne.alistaircrooks.co.uk (/etc/ssh/ssh_host_rsa_key.pub) <root@osx-vm1.crowthorne.alistaircrooks.co.uk>

% ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key.pub
1024 e9:35:90:2d:eb:f1:76:ba:fc:dd:1c:60:8b:ef:4c:4b /etc/ssh/ssh_host_rsa_key.pub (RSA)
%
.Ed
.Pp
The following is an example of RSA key generation:
.Bd -literal
% netpgpkeys --generate\-key
netpgp: default key set to "C0596823"
pub 2048/RSA (Encrypt or Sign) 5bc707d1b495aaf2 2010-04-14
Key fingerprint: 08cb 4867 eeed 454c ce30 610d 5bc7 07d1 b495 aaf2
uid              RSA 2048-bit key \*[Lt]agc@localhost\*[Gt]
netpgp: generated keys in directory /home/agc/.gnupg/5bc707d1b495aaf2
% ls -al /home/agc/.gnupg/5bc707d1b495aaf2
total 8
drwx------  2 agc  agc   512 Apr 13 18:25 .
drwx------  6 agc  agc   512 Apr 13 18:25 ..
-rw-------  1 agc  agc   596 Apr 13 18:25 pubring.gpg
-rw-------  1 agc  agc  1284 Apr 13 18:25 secring.gpg
%
% netpgpkeys --list-keys --home ~/.gnupg/5bc707d1b495aaf2
1 key
pub 2048/RSA (Encrypt or Sign) 5bc707d1b495aaf2 2010-04-14
Key fingerprint: 08cb 4867 eeed 454c ce30 610d 5bc7 07d1 b495 aaf2
uid              RSA 2048-bit key \*[Lt]agc@localhost\*[Gt]

%
.Ed
.Sh SEE ALSO
.Xr netpgp 1 ,
.Xr ssh 1 ,
.Xr ssh-keygen 1 ,
.Xr getpass 3 ,
.\" .Xr libbz2 3 ,
.Xr libnetpgp 3 ,
.Xr ssl 3 ,
.Xr zlib 3
.Sh STANDARDS
The
.Nm
utility is designed to conform to IETF RFC 4880.
.Sh HISTORY
The
.Nm
command first appeared in
.Nx 6.0 .
.Sh AUTHORS
.An -nosplit
.An Ben Laurie ,
.An Rachel Willmer ,
and overhauled and rewritten by
.An Alistair Crooks Aq agc@NetBSD.org .
This manual page was also written by
.An Alistair Crooks .