Difference between revisions of "EncFS"

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== See Also ==
 
== See Also ==
  
[https://defuse.ca/audits/encfs.htm Security audit] of EncFS by Taylor Hornby (January 14, 2014).
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* [https://defuse.ca/audits/encfs.htm Security audit] of EncFS by Taylor Hornby (January 14, 2014).

Revision as of 06:41, 24 February 2014

Related articles

EncFS is a userspace stackable cryptographic file-system similar to eCryptfs, and aims to secure data with the minimum hassle. It uses FUSE to mount an encrypted directory onto another directory specified by the user. It does not use a loopback system like some other comparable systems such as TrueCrypt and dm-crypt.

EncFS is definitely the simplest software if you want to try disk encryption on Linux.

This has a number of advantages and disadvantages compared to these systems. Firstly, it does not require any root privileges to implement; any user can create a repository of encrypted files. Secondly, one does not need to create a single file and create a file-system within that; it works on existing file-system without modifications.

This does create a few disadvantages, though; because the encrypted files are not stored in their own file, someone who obtains access to the system can still see the underlying directory structure, the number of files, their sizes and when they were modified. They cannot see the contents, however.

This particular method of securing data is obviously not perfect, but there are situations in which it is useful.

For more details on how EncFS compares to other disk encryption solution, see Disk Encryption#Comparison table.

Comparison to eCryptFS

eCryptFS is implemented in kernelspace and therefore little bit harder to configure. You have to remember various encryption options (used cyphers, key type, etc...), in EncFS this is not the case, because EncFS is storing that information in its signature so you do not have to remember anything (except the passphrase). The authors of eCryptFS claim it is faster because there is no overhead caused by context switching (between kernel and userspace).

Installation

Install the encfs package.

Usage

To create a secured repository, type:

$ encfs ~/.name ~/name

Note that absolute paths must be used. This will be followed by a prompt about whether you want to go with the default (paranoid options) or expert configuration. The latter allows specifying algorithms and other options. The former is a fairly secure default setup. After entering a key for the encryption, the encoded file-system will be created and mounted. The encoded files are stored, in this example, at ~/.name, and their unencrypted versions in ~/name.

To unmount the file-system, type:

$ fusermount -u ~/name

To remount the file-system, issue the first command, and enter the key used to encode it. Once this has been entered, the file-system will be mounted again.

User friendly mounting

Mount using Gnome Encfs Manager

The Gnome Encfs Manager is an easy to use manager and mounter for encfs stashes featuring per-stash configuration, Gnome Keyring support, a tray menu inspired by Cryptkeeper but using the AppIndicator API and lots of unique features.

The author has created a repo which is more up to date than the AUR package. Add it to /etc/pacman.conf

 [home_moritzmolch_gencfsm_Arch_Extra]
 SigLevel = Never
 Server = http://download.opensuse.org/repositories/home:/moritzmolch:/gencfsm/Arch_Extra/$arch
 sudo pacman -Sy gnome-encfs-manager

Mount using gnome-encfs

gnome-encfs integrates EncFS folders into the GNOME desktop by storing their passwords in the keyring and optionally mounting them at login using GNOME's autostart mechanism. See https://bitbucket.org/obensonne/gnome-encfs/. This method has the advantage that mounting and can automated and the password does not have to be the same as your user password.

Mount using CryptKeeper trayicon

Quite simple app, just install cryptkeeperAUR from AUR and add it to your X session.

Mount at login using pam_encfs

Install pam_encfsAUR. See also:

Single password

Warning: Note that if you will use same password (eg.: using try_first_pass or use_first_pass) for login and encfs (so encfs will mount during your login) then you should use SHA password hashes (Preferably SHA512 with some huge numer of rounds) and (which is most important) secure password, because hash of your password is probably stored in unencrypted form in /etc/shadow and it can be cracked in order to get your encfs password (because it's same as your regular unix login password).

/etc/pam.d/

Note that when you are using try_first_pass parameter to pam_unix.so then you will have to set EncFS to use same password as you are using to login (or vice-versa) and you will be entering just single password. Without this parameter you will need to enter two passwords.

login

This section tells how to make encfs automount when you're logging in by virtual terminal.

Note: If you only want to use it through GDM, you may pass this and go right to the GDM section below.
#%PAM-1.0

auth		required	pam_securetty.so
auth		requisite	pam_nologin.so
auth		sufficient	pam_encfs.so
auth		required	pam_unix.so nullok try_first_pass
#auth		required	pam_unix.so nullok
auth		required	pam_tally.so onerr=succeed file=/var/log/faillog
# use this to lockout accounts for 10 minutes after 3 failed attempts
#auth		required	pam_tally.so deny=2 unlock_time=600 onerr=succeed file=/var/log/faillog
account		required	pam_access.so
account		required	pam_time.so
account		required	pam_unix.so
#password	required	pam_cracklib.so difok=2 minlen=8 dcredit=2 ocredit=2 retry=3
#password	required	pam_unix.so md5 shadow use_authtok
session		required	pam_unix.so
session		required	pam_env.so
session		required	pam_motd.so
session		required	pam_limits.so
session		optional	pam_mail.so dir=/var/spool/mail standard
session		optional	pam_lastlog.so
session		optional	pam_loginuid.so
-session	optional	pam_ck_connector.so nox11
#Automatic unmount (optional):
#session	required	pam_encfs.so
Warning: Note that automatic unmout will process even when there is another session. eg.: logout on VC can unmout encfs mounted by GDM session that is still active.
gdm

This section explains how to make encfs automount when you're logging in by GDM.

Note: For debug purposes you may try automount on virtual console login first. This article has a section about automount on virtual console login.

Edit the file /etc/pam.d/gdm-password.

Insert (do not overwrite) the following into the bottom of gdm-password:

#%PAM-1.0
auth            requisite       pam_nologin.so
auth            required        pam_env.so
auth            sufficient      pam_encfs.so
auth            required        pam_unix.so try_first_pass
auth            optional        pam_gnome_keyring.so
account         required        pam_unix.so
session         required        pam_limits.so
session         required        pam_unix.so
session         optional        pam_gnome_keyring.so auto_start
password        required        pam_unix.so
session         required        pam_encfs.so

Save and exit.

Configuration

Edit /etc/security/pam_encfs.conf :

Recommended: comment out the line

encfs_default --idle=1

This flag will unmount your encrypted folder after 1 minute of inactivity. If you are automounting this on login, you probably would like to keep this mounted for as long as you are logged in.

At the bottom, comment any existing demo entries and add:

#USERNAME       SOURCE                                  TARGET PATH                 ENCFS Options           FUSE Options
foo             /home/foo/EncryptedFolder             /home/foo/DecryptedFolder       -v                    allow_other

Next, edit /etc/fuse.conf: Uncomment:

user_allow_other

To test your config, open a new virtual terminal (e.g. Ctrl+Alt+F4) and login. You should see pam successfuly mount your EncFS folder.

Mount when USB drive with EncFS folders is inserted using fsniper

Simple method to automount (asking for password) encfs when USB drive with EncFS one or more folders in root is inserted. We will use fsniperAUR (filesystem watching daemon using inotify) and git (for askpass binary).

See more at https://github.com/Harvie/Programs/tree/master/bash/encfs/automount (latest version of files used in the How to).

How to

1. You need USB automount working for this - like thunar or nautilus does.
2. Make encrypted folder on your drive, eg.: encfs /media/USB/somename /media/USB/somename.plain (and then unmount everything).
3. Create a ~/.config/fsniper/config file:

watch {
	/etc/ {
		mtab {
			# %% is replaced with the filename of the new file
			handler = encfs-automount.sh %%;
		}
	}
}

4. install helper script:

#!/bin/sh
#	~/.config/fsniper/scripts/encfs-automount.sh
# Quick & dirty script for automounting EncFS USB drives
# TODO:
#  - Unmounting!!!
#
ASKPASS="/usr/lib/git-core/git-gui--askpass"

lock=/tmp/fsniper_encfs.lock
lpid=$(cat "$lock" 2>/dev/null) &&
ps "$lpid" | grep "$lpid" >/dev/null && {
	echo "Another instance of fsniper_encfs is running"
	exit;
}
echo $BASHPID > "$lock";
sleep 2;

echo
echo ==== EncFS automount script for fsniper ====

list_mounts() {
	cat /proc/mounts | cut -d ' ' -f 2
}

list_mounts | while read mount; do
	config="$mount"'/*/.encfs*';
	echo Looking for "$config"
	config="$(echo $config)"
	[ -r "$config" ] && {
		cyphertext="$(dirname "$config")";
		plaintext="$cyphertext".plain
		echo Found config: "$config";
		echo Trying to mount: "$cyphertext to $plaintext";
		list_mounts | grep "$plaintext" >/dev/null && {
			echo Already mounted: "$plaintext"
		} || {
			echo Will mount "$cyphertext to $plaintext"
			"$ASKPASS" "EncFS $cyphertext to $plaintext" | encfs --stdinpass "$cyphertext" "$plaintext"
		}
	}
done
echo

rm "$lock" 2>/dev/null

5. Make sure that /usr/lib/git-core/git-gui--askpass is working for you (that's why you need git package - but you can adjust the helper script).
6. Try fsniper --log-to-stdout in terminal (askpass should appear when USB drive is inserted).
7. Add fsniper --daemon to your session.
8. Do not forget to unmount encfs before removing drive.

See Also