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- Data-at-rest encryption
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From gocryptfs:

  gocryptfs uses file-based encryption that is implemented as a mountable FUSE filesystem. Each file in gocryptfs is stored one corresponding encrypted file on the hard disk.
  The highlights are: Scrypt password hashing, GCM encryption for all file contents, EME wide-block encryption for file names with a per-directory IV.

See the gocryptfs project home for further introduction of its features, benchmarks, etc. See Data-at-rest encryption#Comparison table for an overview of alternative methods and EncFS for the direct alternative.

## Installation

Install gocryptfs or gocryptfs-gitAUR.

As a FUSE filesystem, gocryptfs is fully configurable by the user and stores its configuration files in the user's directory paths.

## Usage

See gocryptfs(1) and its examples first.

Note:

- To achieve its design goal of authenticated encryption, gocryptfs implements a AES-EME encryption mode (for filenames, the content is encrypted using standard libraries). While the EME mode is not widely used/audited yet, gocryptfs encryption modes bring integrity protection for the data.
- See the project's tracking bug report regarding findings of the first security audit for more information.

Tip:

- Execute `gocryptfs -speed` to test throughput for available encryption modes. The automatic selection will choose the fastest mode available for the system.
- As a first-time user, check the gocryptfs best practices.
- Upon initialization of the cryptography for a directory, the master key is output before it is cryptographically wrapped in the `gocryptfs.conf` file. See Recreate configuration using the masterkey for an emergency restore procedure.
- A `-fido2` option allows the convenience of U2F hardware tokens to initialize and mount the encrypted data. Be aware token features, for example PIN entry, cannot be toggled currently and can be different for token models.

### Example using normal mode

Create `cipher` directory to store encrypted data, and `plain` directory to access them decrypted. Then, run gocryptfs initialization to setup encryption.

    $ mkdir cipher plain
    $ gocryptfs -init cipher
    Choose a password for protecting your files.
    Password:
    [...]

To open the encrypted directory `cipher` and access it from `plain`:

    $ gocryptfs cipher plain
    Password:
    Decrypting master key
    Filesystem mounted and ready

You should now have a working gocryptfs that is stored in `cipher` and mounted to `plain`. You can verify this by creating a blank file in the `plain` directory. This file will show up encrypted in the `cipher` directory.

    $ touch plain/test.txt
    $ ls cipher
      gocryptfs.conf  gocryptfs.diriv  ZSuIZVzYDy5-TbhWKY-ciA==

### Example using reverse mode

A major application for file-based encryption methods are encrypted backups. FUSE-based filesystems are flexible for this, since they allow a wide array of backup destinations using standard tools. For example, a gocryptfs-encrypted FUSE mount point can be easily created directly on a Samba/NFS share or Dropbox location, synchronized to a remote host with rsync, or just be manually copied to a remote backup storage.

Warning: By default the `gocryptfs.conf` file is stored within the backup directory for convenience. If you upload the `gocryptfs.conf` file to an online source, your backup can be decrypted if your password is known or cracked. Using a strong password will lower the chances of a successful attack. [1] You can choose to use a `gocryptfs.conf` file from another location by providing the `-config` option along with the path to your configuration file.

The reverse mode of gocryptfs is particularly useful for creating encrypted backups, since it requires virtually no extra storage capacity on the machine to back up.

The following shows an example of user archie creating a backup of `/home/archie`:

First, archie initializes the configuration for the home directory:

    $ gocryptfs -init -reverse /home/archie

    Choose a password for protecting your files.
    Password:
    ...

Second, an empty directory for the encrypted view of the home directory is created and mounted:

    $ mkdir /tmp/crypt
    $ gocryptfs -reverse /home/archie /tmp/crypt
    Password:
    Decrypting master key

    Your master key is:
    ...
    Filesystem mounted and ready.
    $

Tip: A number of options to exclude files or directories from the reverse mount are available; see gocryptfs(1) § EXCLUDING_FILES. Note that with software like rsync errors or warnings may occur if exclusions are done later only.[2]

Third, archie creates a backup of the encrypted directory, a simple local copy for this example:

    $ cp -a /tmp/crypt /tmp/backup

and done.

The encrypted directory can stay mounted for the user session, or be unmounted manually:

    $ fusermount -u /tmp/crypt
    $ rmdir /tmp/crypt

To restore from the encrypted backup, a plain-text view is mounted using gocryptfs's normal mode:

    $ mkdir /tmp/restore
    $ gocryptfs /tmp/backup/ /tmp/restore
    Password:
    Decrypting master key
    ...
    Filesystem mounted and ready.
    $

Now the required files can be restored.

## GUI wrappers

There are a couple of applications available that provide a graphical user interface for gocryptfs.

### gocryptfs-ui

A bash script gocryptfs-ui provides a simple zenity GUI around the gocryptfs command line utility to mount and unmount an encrypted directory. It includes a desktop launcher. Install it from gocryptfs-uiAUR.

### cryptor

A vala/gtk3 based application providing a GUI to create and mount encrypted directories. It can store configuration files with a list of encrypted directories, has tray-icon support and includes a desktop launcher. Install it from cryptorAUR.

## See also

- A first security audit of gocryptfs
- RFC 5297 Synthetic Initialization Vector (SIV) Authenticated Encryption Using the Advanced Encryption Standard (AES)
- gocryptfs-ui (gocryptfs-uiAUR) is a simple GUI for gocryptfs.
- cryptor (cryptorAUR) a simple GUI application for gocryptfs.

Categories:

- Data-at-rest encryption
- FUSE