Tomb/doc/tomb.1

.TH tomb 1 "June 20, 2013" "tomb"

.SH NAME
Tomb \- the Crypto Undertaker

.SH SYNOPSIS
.B
.IP "tomb [options] command [arguments]"

.SH DESCRIPTION

Tomb is an application to manage the creation and access of encrypted
storage files: it can be operated from commandline and it can
integrate with a user's graphical desktop.

Tomb generates encrypted storage files to be opened and closed using
their associated keys, which are also protected with a password chosen
by the user. To create, open and close tombs a user will need super
user rights to execute the tomb commandline utility.

A tomb is like a locked folder that can be safely transported and
hidden in a filesystem; it encourages users to keep their keys
separate from tombs, for instance keeping a tomb file on your computer
harddisk and its key file on a USB stick.


.SH COMMANDS

.B
.IP "dig"
Generates a file that can be used as a tomb and will occupy as much
space as its desired initial size, the unlocked \fI.tomb\fR file can
then be locked using a \fIkey\fR. It takes a mandatory \fI-s\fR option which is
the size in megabytes (MiB). Tombs are digged using
low-quality random data (/dev/urandom).

.B
.IP "forge"
Creates a new \fIkey\fR and prompts the user for a \fIpassword\fR to
protect its usage. This operation requires high quality random data
(/dev/random) which can take quite some time to be gathered on a
server: it works better on a desktop where the mouse can be moved
around for entropy. The default cipher to protect the key is AES256, a
custom one can be specified using the \fI-o\fR option, for a list of
supported ciphers use \fI-v\fR. For additional protection against
dictionary attacks on keys, the (experimental) \fI--kdf\fR option can
be used when forging a key, making sure that the \fItomb-kdb-pbkdf2\fR
binaries in \fIextras/kdf\fR were compiled and installed on the
system.

.B
.IP "lock"
Initializes and locks an empty tomb (made with \fIdig\fR) using a key
(made with \fIforge\fR), making it ready for usage. After this
operation, the tomb can only be open in possession of the key and
knowing its password. As in any other command requiring a key, the
option \fI-k\fR should be used to specify a key file. The \fI-o\fR
option can be used to specify the cipher specification: default is
"aes-xts-plain64:sha256", old versions of Tomb used "aes-cbc-essiv:sha256".
This operation requires root privileges to loopback mount, format the tomb (using
LUKS and Ext4), then set the key in its first LUKS slot.

.B
.IP "open"
Opens an existing \fI.tomb\fR (first argument) using a key (\fI-k\fR),
if a second argument is given it will indicate the \fImountpoint\fR
where the tomb should be made accessible, else the tomb is mounted in
a directory inside /media. The option \fI-o\fR can be used to pass
mount(8) options (default: rw,noatime,nodev).

.B
.IP "list"
List all the tombs found open, including information about the time
they were opened and the hooks that they mounted. If the first
argument is present, then shows only the tomb named that way or
returns an error if its not found. If the option
\fI--get-mountpoint\fR is used then print a simple list of currently
open tomb mountpoint paths.

.B
.IP "index"
Creates or updates the search indexes of all tombs currently
open: enables use of the \fIsearch\fR command using simple word
patterns on file names. Indexes are created using mlocate updatedb(8) and
stored in a file inside the tomb's root. To avoid indexing
a specific tomb simply touch a \fI.noindex\fR file in its root.

.B
.IP "search"
Searches through all tombs currently open for filenames matching one
or more text patterns given as arguments. Search returns a list of
files found in all open tombs on which the \fIindex\fR command was run
at least once.

.B
.IP "close"
Closes a currently open tomb.  If more tombs are open, the first
argument should be used to specify the name of the tomb to be closed,
or \fIall\fR to close all currently open tombs. This command fails if
the tomb is in use by running processes (to force close, see
\fIslam\fR below).

.B
.IP "slam"
Closes a tomb like the command \fIclose\fR does, but it doesn't fails
even if the tomb is in use by other application processes: it looks
for them and violently kills \-9 each of them. This command may
provoke unsaved data loss, but assists users to face surprise
situations.


.B
.IP "passwd"
Changes the password protecting a key file specified using
\fI-k\fR. The user will need to know the key's current password, then
its content will be decoded and reencoded using the new one. This
action can't be forced if the current password is not known. If the
key file is broken (missing headers) this function also attempts its
recovery.

.B
.IP "setkey"
Changes the key file that locks a tomb, substituting the old one with
a new one. Both the old and the new key files are needed for this
operation and their passwords must be known. The new key must be
specified using the \fI-k\fR option, the first argument should be the old
key and the second and last argument the tomb file.

.B
.IP "resize"
Increase the size of a tomb file to the amount specified by the
\fI-s\fR option, which is the new size in megabytes (MiB). Full access to the tomb using
a key (\fI-k\fR) and its password is requires. Tombs can only grow and
can never be made smaller. This command makes use of the cryptsetup
resize feature and the resize2fs command: its much more practical than
creating a new tomb and moving everything into it.

.B
.IP "engrave"
This command transforms a tomb key into an image that can be printed
on paper and phisically stored as backup, i.e. hidden in a book. It
Renders a QRCode of the tomb key, still protected by its password: a
PNG image (extension \fI.qr.png\fR) will be created in the current
directory and can be later printed (fits an A4 or Letter format).  To
recover an engraved key one can use any QRCode reader on a smartphone:
save it into a file and then use that file as a key (\fI-k\fR).

.B
.IP "bury"
Hides a tomb key (\fI-k\fR) inside a \fIjpeg image\fR (first argument)
using \fIsteganography\fR: the image will change in a way that cannot
be noticed by human eye and hardly detected by data analysis. This
option is useful to backup tomb keys in unsuspected places; it depends
from the availability of \fIsteghide\fR.

.B
.IP "exhume"
This command recovers from jpeg images the keys that were previously
hidden into them using \fIbury\fR.  Exhume requires a key filename
(\fI-k\fR) and a \fIjpeg image\fR file (first argument) known to be
containing a key. If the right key password is given, the key will be
exhumed. If the password is not known, it is very hard to verify if a
key is buried in any image or not.

.SH OPTIONS
.B
.B
.IP "-s \fI<MBytes>\fR" 
When digging or resizing a tomb, this option must be used to specify
the \fIsize\fR of the new file to be created. Units are megabytes (MiB).
.B
.IP "-k \fI<keyfile>\fR"
When opening a tomb, this option can specify the location of the key
file to use. Keys are created with the same name of the tomb file
adding a '.key' suffix, but can be later renamed and transported on
other media.  If \fI<keyfile>\fR is "-" (dash), it will read it from
stdin.
.B
.IP "--kdf \fI<iterations>\fR"
Activate the KDF feature against dictionary attacks when creating a
key: forces a delay of \fI<iterations>\fR (integer multiplied by 10k)
every time this key is used.
.B
.IP "-n"
Skip processing of post-hooks and bind-hooks if found inside the tomb.
See the \fIHOOKS\fR section in this manual for more information.
.B
.IP "-o"
Manually specify mount options to be used when opening a tomb instead
of the default \fIrw,noatime,nodev\fR, i.e. to mount a tomb read-only
(ro) to prevent any modification of its data. Can also be used to
change the symmetric encryption algorithm for keys during \fIforge\fR
operations (default \fIAES256\fR) or the LUKS encryption method during
\fIlock\fR operations (default \fIaes-xts-plain64:sha256\fR).
.B
.IP "-f"
Force flag, currently used to override swap checks, might be
overriding more wimpy behaviours in future, but make sure you know
what you are doing if you force an operation.
.B
.IP "-h"
Display a help text and quit.
.B
.IP "-v"
Display version and quit.
.B
.IP "-q"
Run more quietly
.B
.IP "-D"
Print more information while running, for debugging purposes

.SH DEV MODE
.B
.IP "--no-color"
Suppress colors in console output (needed for string parsing by
wrappers).
.B
.IP "--unsecure-dev-mode"
Enable using dev-mode arguments, i.e. to pass passwords from
commandline options. This is mostly used needed for execution by
wrappers and testing suite.
.B
.IP "--use-urandom"
Use an inferior quality random source to improve the speed of key
generation at the cost of security (neede for the testing suite).
.B
.IP "--sudo-pwd <string>"
Use string as password when needed for privilege escalation via sudo.
.B
.IP "--tomb-pwd <string>"
Use string as password when needed on tomb.
.B
.IP "--tomb-old-pwd <string>"
Use string as old password when needed in tomb commands requiring
multiple keys, like \fIpasswd\fR or \fIsetkey\fR.
.B
.IP "-U --uid"
Switch to this user ID when dropping privileges.
.B
.IP "-G --gid"
Switch to this group ID when dropping privileges.
.B
.IP "-T --tty"
Switch to this TTY terminal when dropping privileges.

.SH HOOKS

Hooks are special files that can be placed inside the tomb and trigger
actions when it is opened and closed; there are two kinds of such
files: \fIbind-hooks\fR and \fIpost-hooks\fR can be placed in the
base root of the tomb.

.B
.IP "bind-hooks"
This hook file consists of a simple two column list of files or
directories inside the tomb to be made directly accessible inside the
current user's home directory. Tomb will use the "mount \-o bind"
command to bind locations inside the tomb to locations found in $HOME
so in the first column are indicated paths relative to the tomb and in
the second column are indicated paths relative to $HOME contents, for
example:
.EX
  mail          mail
  .gnupg        .gnupg
  .fmrc         .fetchmailrc
  .mozilla      .mozilla
.EE

.B
.IP "post-hooks"
This hook file gets executed as user by tomb right after opening it;
it should be a regular shell script, starting with a shell bang. Tomb
executes this hook as user (dropping root priviledges) and giving it
two arguments: "$1" is "open" or "close" depending from the tomb
command given, "$2" is the full path to the mountpoint where the tomb
is open.

.SH PRIVILEGE ESCALATION

The tomb commandline tool needs to acquire super user rights to
execute most of its operations: to do so it uses sudo(8), while
pinentry(1) is adopted to collect passwords from the user. Tomb
executes as super user only when required.

To be made available on multi user systems, the superuser execution of
the tomb script can be authorized for users without jeopardizing the
whole system's security: just add such a line to \fI/etc/sudoers\fR:

.EX
	username ALL=NOPASSWD: /usr/local/bin/tomb
.EE

.SH SWAP

On execution of certain commands Tomb will complain about swap memory
on disk when that is presend and \fIabort if your system has swap
activated\fR. You can disable this behaviour using the
\fI--force\fR. Before doing that, however, you may be interested in
knowing the risks of doing so:
.IP \(bu
During such operations a lack of available memory could cause the swap
to write your secret key on the disk.
.IP \(bu
Even while using an opened tomb, another application could occupy too
much memory so that the swap needs to be used, this way it is possible
that some contents of files contained into the tomb are physically
written on your disk, not encrypted.
.P

If you don't need swap, execute \fI swapoff -a\fR. If you really need
it, you could make an encrypted swap partition. Tomb doesn't detect if
your swap is encrypted, and will complain anyway.

.SH EXAMPLES

.IP \(bu
Create a 128MB large "secret" tomb and its keys, then open it:

.EX
	tomb dig -s 128 secret.tomb

	tomb forge secret.tomb.key

	tomb lock secret.tomb -k secret.tomb.key

	tomb open secret.tomb -k secret.tomb.key
.EE

.IP \(bu
Open a Tomb using the key from a remote SSH shell, without saving any
local copy of it:

.EX
	ssh user@my.shell.net 'cat .secrets/tomb.key' | tomb open secret.tomb -k -	
.EE

.IP \(bu
Create a bind hook that places your GnuPG folder inside the tomb, but
makes it reachable from the standard $HOME/.gnupg location every time
the tomb will be opened:

.EX
	tomb open GPG.tomb -k GPG.tomb.key
	echo ".gnupg .gnupg" > /media/GPG.tomb/bind-hooks
	mv ~/.gnupg /media/GPG.tomb/.gnupg && mkdir ~/.gnupg
	tomb close GPG && tomb open GPG.tomb -k GPG.tomb.key
.EE

.IP \(bu
Script a tomb to launch the Firefox browser every time is opened,
keeping all its profile data inside it:

.EX
	tomb open FOX.tomb -k FOX.tomb.key
	cat <<EOF > /media/FOX.tomb/post-hooks
#!/bin/sh
if [ "$1" = "open" ]; then
  firefox -no-remote -profile "$2"/firefox-pro &
fi
EOF
	chmod +x     /media/FOX.tomb/post-hooks
.EE

.IP \(bu
Script a tomb to archive Pictures using Shotwell, launching it on open:

.EX
	tomb open Pictures.tomb -k Pictures.tomb.key
	cat <<EOF > /media/Pictures.tomb/bind-hooks
Pictures Pictures
EOF
        cat <<EOF > /media/Pictures.tomb/post-hooks
#!/bin/sh
if [ "$1" = "open" ]; then
  which shotwell > /dev/null
  if [ "$?" = "0" ]; then
    shotwell -d "$2"/Pictures/.shotwell &
  fi
fi
EOF
	chmod +x /media/Pictures.tomb/post-hooks
.EE

.SH BUGS
Please report bugs on the tracker at
.UR https://bugs.dyne.org
.UE

Get in touch with developers via mail by subscribing the "crypto" mailinglist on \fIhttp://lists.dyne.org\fR or via the #dyne chat channel on \fIhttps://irc.dyne.org\fR.

.SH AUTHORS

Tomb is designed, written and maintained by Denis Roio aka Jaromil.

Tomb includes code by Anathema, Boyska and Hellekin O. Wolf.

Tomb's artwork is contributed by Jordi aka Mon Mort

Testing and reviews are contributed by Dreamer, Shining, Mancausoft,
Asbesto Molesto and Nignux.

Cryptsetup was developed by Christophe Saout and Clemens Fruhwirth

.SH COPYING

This manual is Copyright (c) 2011-2013 by Denis Roio <\fIjaromil@dyne.org\fR>

This manual includes contributions by Boyska.

Permission is  granted to copy,  distribute and/or modify  this manual
under the terms of the  GNU Free Documentation License, Version 1.1 or
any  later   version  published  by  the   Free  Software  Foundation.
Permission is granted  to make and distribute verbatim  copies of this
manual page  provided the above  copyright notice and  this permission
notice are preserved on all copies.

.SH AVAILABILITY

The most recent version of Tomb sourcecode and up to date
documentation is available for download from its website on
\fIhttp://tomb.dyne.org\fR.

.SH SEE ALSO

.B
.IP cryptsetup(8)

GnuPG website on http://www.gnupg.org

DM-Crypt website on http://www.saout.de/misc/dm-crypt

LUKS website, http://code.google.com/p/cryptsetup