Difference between revisions of "TrueCrypt"

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Add the module to /etc/modules-load.d/:
 
Add the module to /etc/modules-load.d/:
 
  # tee /etc/modules-load.d/truecrypt.conf <<< "truecrypt"
 
  # tee /etc/modules-load.d/truecrypt.conf <<< "truecrypt"
 +
 +
This didn't work for me (module truecrypt seems to be non-existent now), but adding "loop" module worked
 +
# tee /etc/modules-load.d/truecrypt.conf <<< "loop"
  
 
{{Note|It does not appear that loading a module applies with TrueCrypt 7.1a, the current version in Arch as of 4/19/2013. The above advice may be outdated with respect to the module, however it is still important to enable '''FUSE''', '''loop''' and your encryption algorithm (e.g. '''AES''', '''XTS''', '''SHA512''') in custom kernels.
 
{{Note|It does not appear that loading a module applies with TrueCrypt 7.1a, the current version in Arch as of 4/19/2013. The above advice may be outdated with respect to the module, however it is still important to enable '''FUSE''', '''loop''' and your encryption algorithm (e.g. '''AES''', '''XTS''', '''SHA512''') in custom kernels.

Revision as of 04:29, 19 June 2013

Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki Template:Article summary wiki Template:Article summary end TrueCrypt is a free open source on-the-fly encryption (OTFE) program. Some of its features are:

  • Virtual encrypted disks within files that can be mounted as real disks.
  • Encryption of an entire hard disk partition or a storage device/medium.
  • All encryption algorithms use the LRW mode of operation, which is more secure than CBC mode with predictable initialization vectors for storage encryption.
  • "Hidden volumes" within a normal "outer" encrypted volume. A hidden volume can not be distinguished from random data without access to a passphrase and/or keyfile.

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

Installation

Install truecrypt from the official repositories. If you use any kernel other than linux install the corresponding kernel module.

If you are using truecrypt to encrypt a virtual filesystem (e.g. a file), the module will be automatically loaded whenever you run the truecrypt command. Add it to the MODULES array in /etc/rc.conf.

If you are using truecrypt to encrypt a physical device (e.g. a hard disk or usb drive), you will likely want to load the module during the boot sequence:

Add the module to /etc/modules-load.d/:

# tee /etc/modules-load.d/truecrypt.conf <<< "truecrypt"

This didn't work for me (module truecrypt seems to be non-existent now), but adding "loop" module worked

# tee /etc/modules-load.d/truecrypt.conf <<< "loop"
Note: It does not appear that loading a module applies with TrueCrypt 7.1a, the current version in Arch as of 4/19/2013. The above advice may be outdated with respect to the module, however it is still important to enable FUSE, loop and your encryption algorithm (e.g. AES, XTS, SHA512) in custom kernels. If you only want to open and access an existing truecrypt container, this can also be done with cryptsetup i.e. without installing Truecrypt.

Encrypting a file as a virtual volume

The following instructions will create a file that will act as a virtual filesystem, allowing you to mount it and store files within the encrypted file. This is a convenient way to store sensitive information, such as financial data or passwords, in a single file that can be accessed from Linux, Windows, or Macs.

To create a new truecrypt file interactively, type the following in a terminal:

$ truecrypt -t -c

Follow the instructions, choosing the default values unless you know what you are doing:

Volume type:
 1) Normal
 2) Hidden
Select [1]: 1
Enter file or device path for new volume: /home/user/myEncryptedFile.tc
Enter volume size (bytes - size/sizeK/sizeM/sizeG): 32M
Encryption algorithm:
 1) AES
 2) Blowfish
 3) CAST5
 4) Serpent
 5) Triple DES
 6) Twofish
 7) AES-Twofish
 8) AES-Twofish-Serpent
 9) Serpent-AES
10) Serpent-Twofish-AES
11) Twofish-Serpent
Select [1]: 1
Hash algorithm:
 1) RIPEMD-160
 2) SHA-1
 3) Whirlpool
Select [1]: 1  

Filesystem:

1) None
2) FAT
3) Linux Ext2
4) Linux Ext3
5) Linux Ext4

Select [2]:

Enter password for new volume '/home/user/myEncryptedFile.tc': *****************************
Re-enter password: *****************************
Enter keyfile path [none]: 
Please type at least 320 randomly chosen characters and then press Enter:
Done: 32.00 MB  Speed: 10.76 MB/s  Left: 0:00:00  
Volume created.

You can now mount the new encrypted file to a previously-created directory:

$ truecrypt -t /home/user/myEncryptedFile.tc /home/user/myEncryptedFileFolder
Note: Truecrypt requires root privileges and as such, running the above command as a user will attempt to use sudo for authentication. To work with files as a regular user, please seeMount volumes as a normal user.

Once mounted, you can copy or create new files within the encrypted directory as if it was any normal directory. When you are you ready to re-encrypt the contents and unmount the directory, run:

$ truecrypt -t -d

Again, this will require administrator privileges through the use of sudo. After running it check if the files that are to be encrypted are indeed no longer in the directory. (might want to try unimportant data first) If they are still there, note that rm doesn't make the data unrecoverable.

For more information about truecrypt in general, run:

$ man truecrypt
Note: As of 1:7.1a-1 dont see a man or info page.

Several options can be passed at the command line, making automated access and creation a simple task. The man page is highly recommended reading.

Encrypting a physical volume

If you want to use a keyfile, create one with this command:

truecrypt --create-keyfile /etc/disk.key

By default both passphrase and key will be needed to unlock the volume.

Create a new volume in the device /dev/sda1:

truecrypt --volume-type normal -c /dev/sda1

Map the volume to /dev/mapper/truecrypt1:

truecrypt -N 1 /dev/sda1

If this command does not for you try this to map the volume:

truecrypt --filesystem=none --slot=1 /dev/sda1

If you want to use another file system than ext3 simply format the disk like you normally would, except use the path /dev/mapper/truecrypt1.

mkfs.ext3 /dev/mapper/truecrypt1

Mount the volume:

mount /dev/mapper/truecrypt1 /media/disk

Map and mount a volume:

truecrypt /dev/sda1 /media/disk

Unmount and unmap a volume:

truecrypt -d /dev/sda1

Creating a hidden volume

First, create a normal outer volume as described above.

Map the outer volume to /dev/mapper/truecrypt1:

truecrypt -N 1 /dev/sda1

Create a hidden truecrypt volume in the free space of the outer volume:

 truecrypt --type hidden -c /dev/sda1

You need to use another passphrase and/or keyfile here than the one you used for the outer volume.

Unmap the outer truecrypt volume and map the hidden one:

truecrypt -d /dev/sda1
truecrypt -N 1 /dev/sda1

Just use the passphrase you chose for the hidden volume and TrueCrypt will automatically choose it before the outer.

Create a file system on it (if you have not already) and mount it:

mkfs.ext3 /dev/mapper/truecrypt1
mount /dev/mapper/truecrypt1 /media/disk

Map and mount the outer volume with the hidden write-protected:

truecrypt -P /dev/sda1 /media/disk

Mount a special filesystem

Template:Box Note

In my example I want to mount a ntfs-volume, but truecrypt does not use ntfs-3g by default (so there is no write access; checked in version 6.1). The following command works for me:

truecrypt --filesystem=ntfs-3g --mount /file/you/want/to/mount

You may also want to mount ntfs volume without execute flag on all files

truecrypt --filesystem=ntfs-3g --fs-options=users,uid=$(id -u),gid=$(id -g),fmask=0113,dmask=0002

Mount volumes via fstab

First of all, we need to write a script which will handle the way mounting via fstab is done. Place the following in /sbin/mount.truecrypt:

#!/usr/bin/env sh 
DEV="$1"
MNTPT="$2"
OPTIONS=""
TCOPTIONS=""
shift 3
IFS=','
for arg in $*; do
    if [ "${arg}" == "system" ]; then
        TCOPTIONS="${TCOPTIONS}-m=system "
    elif [[ "${arg}" == fs=* ]]; then
        FS=${arg#*=}
        TCOPTIONS="${TCOPTIONS}--filesystem=${FS} "
    else
         OPTIONS="${OPTIONS}${arg},"
    fi
done
truecrypt ${DEV} ${MNTPT} ${TCOPTIONS% *} --fs-options="${OPTIONS%,*}"

Also do not forget to make the file executable:

chmod +x /sbin/mount.truecrypt

Finally, add the device to fstab somewhat like this:

/dev/sdb3 /mnt truecrypt fs=vfat,defaults 0 0

Mount volumes using a systemd service

To use Truecrypt with systemd, it is advised to use truecrypt as decryptor and mapper and fstab to do the mounting of encrypted volumes.

First, create this service systemd/Services#truecrypt_volume_setup in /usr/lib/systemd/system. Enable it with (assuming your encrypted volume is /dev/sda2):

# systemctl enable truecrypt@dev-sda2.service

Secondly, create a line similar to that one in your fstab (the 2 means your fs will be fscked regularly):

/etc/fstab
/dev/mapper/truecrypt1  /home/          ext4 defaults        0       2

And you should be set.

Mount volumes as a normal user

TrueCrypt needs root privileges to work: this procedure will allow normal users to use it, also giving writing permissions to mounted volumes.

Both methods below require sudo. Make sure it is configured before proceeding.

Method 1: add a truecrypt group

Create a new group called truecrypt and give it the necessary permissions. Any users that belongs to that group, will be able to use TrueCrypt.

# groupadd truecrypt

Edit the sudo configuration:

# visudo

Append the following lines at the bottom of the sudo configuration file:

# Users in the truecrypt group are allowed to run TrueCrypt as root.
%truecrypt ALL=(root) NOPASSWD:/usr/bin/truecrypt

You can now add your users to the truecrypt group:

# gpasswd -M first_user,second_user,etc truecrypt
Note: In order to make these changes active, any user that has been added to the truecrypt group have to logout.

After that, you can mount your device by

# truecrypt --mount /PATH/TO/DEVICE /PATH/TO/MOUNTPOINT

Default mountpoint is /media/truecrypt1. Normally, it is not necessary to explicitly specify the filesystem of your device using the --filesystem flag.

It is definitely reasonable to give truecrypt some permission masks. Otherwise, every file on your mounted device will be executable. So instead of the above, you can use

# truecrypt --fs-options=users,uid=$(id -u),gid=$(id -g),fmask=0113,dmask=0002 --mount /PATH/TO/DEVICE /PATH/TO/MOUNTPOINT

and add this line to your bash configuration file, ~/.bashrc as an alias:

alias tc1='truecrypt --fs-options=users,uid=$(id -u),gid=$(id -g),fmask=0113,dmask=0002 --mount /PATH/TO/DEVICE /PATH/TO/MOUNTPOINT'

To mount this specific device, use

# tc1

as a normal user.

Method 2: sudo simplified

Simply enable desired user to run truecrypt without a password:

# visudo

Append the following:

USERNAME ALL = (root) NOPASSWD:/usr/bin/truecrypt

alternatively, if you make use of the wheel group:

%wheel ALL = (root) NOPASSWD:/usr/bin/truecrypt

If you have any difficulties with permissions as a normal user, just add the '-u' flag to the truecrypt mount command, for example:

$ truecrypt -u /home/user/myEncryptedFile.tc /home/user/myEncryptedFileFolder

Automatic mount on login

Simply add

$ truecrypt /home/user/myEncryptedFile.tc /home/user/myEncryptedFileFolder <<EOF
password
EOF

to your startup procedure. Do not use the -p switch, this method is more secure. Otherwise everyone can just look up the password via ps and similar tools, as it is in the process name! source

The most recent truecrypt has a couple of followup questions. If you have expect installed, this will work (assuming no keyfile and no desire to protect hidden volume), saved to a file with root-only perms called from /etc/rc.local:

#! /bin/bash
expect << EOF
spawn /usr/bin/truecrypt /path/to/myEncryptedFile /mnt/point 
expect "Enter password"
send "somelonggoodpassword\n"
expect "Enter keyfile"
send "\n"
expect "Protect hidden volume"
send "\n"
expect eof;
EOF

Of course, this isn't as secure as entering your password manually. But for some use cases, such as when your truecrypt filesystem is in a file on shared storage, it's better than being unencrypted.

Safely unmount and unmap volumes (on shutdown)

You can unmount a specific device by

# truecrypt -d /PATH/TO/MOUNTPOINT

or leave away the path to unmount all truecrypt volumes.

If you want your truecrypt device to be unmounted automatically at shutdown, add the following to the file /etc/rc.local.shutdown:

if (/usr/bin/truecrypt --text --list)
then {
/usr/bin/truecrypt -d
sleep 3
}
fi

You can also leave away the sleep command, it is just to give the unmounting some time to complete before the actual shutdown.

If you're using systemd, there is a service trying to unmount truecrypt-encrypted filesystems at shutdown automatically on the systemd/Services page.

Errors

TrueCrypt is already running

If a messagebox TrueCrypt is already running appears when starting TrueCrypt, check for a hidden file in the home directory of the concerned user called .TrueCrypt-lock-username. Substitute username with the individual username. Delete the file and start TrueCrypt again.

Deleted stale lockfile

If you always get a message "Delete stale lockfile [....]" after starting Truecrypt, the Truecrypt process with the lowest ID has to be killed during Gnome log out. A user in the Ubuntuforum provided the following solution: edit

/etc/gdm/PostSession/Default 

and add the following line before exit 0:

kill $(ps -ef | grep truecrypt | tr -s ' ' | cut -d ' ' -f 2)

Issues with Unicode file/folder names

NTFS

Should files resp. folders containing Unicode characters in their names be incorrectly or not at all displayed on TrueCrypt NTFS volumes (while e. g. being correctly handled on non-encrypted NTFS partitions), first verify that you have the NTFS-3G driver installed and then create the following symlink as root:

ln -s /sbin/mount.ntfs-3g /sbin/mount.ntfs

That will cause TrueCrypt to automatically use this driver for NTFS volumes, having the same effect as the explicit use of

truecrypt --filesystem=ntfs-3g /path/to/volume

via the console.

One may also consider setting e. g.

rw,noatime

amongst other options in the TrueCrypt GUI (Settings → Preferences → Mount Options).

FAT

Similarly, FAT32 volumes created using Windows may use Unicode rather than ISO 8859-1. In order to use UTF-8, set the mount option

iocharset=utf8

when mounting such volumes, or globally as described above.

Unmount error (device mapper)

If you always get a message "device-mapper: remove ioctl failed: Device or resource busy" when attempting to dismount your truecrypt volume, the solution is to goto: Setting > Preferences > System Integration > Kernel Service and check the box

Do not use kernel cryptographic services
Note: I have only seen this with a truecrypt partition. Not with a truecrypt file.

Mount error (device mapper, truecrypt partition)

When attempting to mount your truecrypt volume, a message like this one may appear:

Error: device-mapper: create ioctl failed: Device or resource busy
Command failed

If so, run:

# cryptsetup remove /dev/mapper/truecrypt1

Failed to set up a loop device

If you get a message "Failed to set up a loop device" when trying to create/mount a TrueCrypt volume, it may be because you updated your kernel recently without rebooting. Rebooting should fix this error.

Otherwise, check if loop has been loaded as kernel module:

lsmod | grep loop

If not listed, retry the TrueCrypt command after modprobe loop. Should it work, consider to add loop to the modules in /etc/modules-load.d:

# tee /etc/modules-load.d/truecrypt.conf <<< "loop"
Note: As of udev 181-5, the loop device module is no longer auto-loaded, and the procedure described here is necessary.

See also