gocryptfs-standalone

Project Status

Use case

Work with a gocryptfs encrypted directory (for example synchronized via a cloud service like Google Drive) on machines where gocryptfs or a FUSE backend can not be installed (no admin rights). The tool runs as a standalone executable on Linux, macOS and Windows.

Only vaults created with gocryptfs -init -plaintextnames are supported (feature flags HKDF GCMIV128 PlaintextNames). Every other vault is refused so it never gets damaged.

Installation

Download the executable of your platform from the releases (linux, macos or windows, each for x64 and arm64), unpack it and run it, no installation or admin rights needed. SHA256SUMS lists the checksums of all archives.

The executables are not signed by a registered developer, so:

• macOS blocks downloaded ones at first: remove the quarantine flag with xattr -d com.apple.quarantine gocryptfs-standalone-macos-* (or allow it under "System Settings → Privacy & Security").
• Windows SmartScreen may warn on first start ("More info → Run anyway").
• Linux executables need a glibc based distribution (not Alpine/musl).

With node (26 or newer) the package can be used directly as well: npx gocryptfs-standalone ….

To build the executable of the current platform yourself: yarn build:standalone (and yarn test:standalone to check it end to end).

Usage

gocryptfs-standalone init <vault> [--scryptn 16]
gocryptfs-standalone info <vault>
gocryptfs-standalone cat <vault> <path> > file
gocryptfs-standalone decrypt <vault> <target>
gocryptfs-standalone encrypt <source> <vault>
gocryptfs-standalone sync <plaintext> <vault> [--dry-run] [--trash-days 30]

decrypt, encrypt and sync accept --exclude <pattern> (repeatable).

The vault's configuration file is looked up as gocryptfs.conf and then as .gocryptfs.conf in the vault directory (init creates gocryptfs.conf). Every command accepts --config <path> to use a configuration file located elsewhere, like gocryptfs' -config option (for example to keep it out of the cloud). Both names are reserved in the vault root and never synchronized.

decrypt and encrypt work one way: existing files on the target side get overwritten, nothing gets deleted. Modification times, permissions and symbolic links are carried over. Vaults created with init can be mounted with gocryptfs (-init -plaintextnames compatible).

Synchronization

sync keeps a plaintext directory and a vault in sync in both directions. After each run the state of both sides is remembered (a json file in the user's configuration directory: %APPDATA%\gocryptfs-standalone on Windows, $XDG_CONFIG_HOME/gocryptfs-standalone or ~/.config/gocryptfs-standalone elsewhere). Compared to that state:

Without a state (first run) both sides get merged, files existing on both sides are compared by content, and nothing gets deleted. The trash lives next to the state (pairs/<id>/trash, vault files stay encrypted there) and gets purged after 30 days (--trash-days). Entries changing while being synchronized are skipped and retried next time, a lock prevents parallel runs of the same pair. --dry-run only shows what would happen.

Excludes

Excluded entries are left alone on both sides, as if they did not exist. Excluding something already synchronized never deletes it. Patterns follow gitignore conventions:

Supported globs: *, **, ?, [...] and {a,b}. Matching is case insensitive on macOS and Windows.

Configured pairs and background synchronization

Pairs of a plaintext directory and a vault can be configured once and then be synchronized by name, all at once or periodically in the background:

# Asks for the password, verifies it and stores it in the keychain.
gocryptfs-standalone pair add documents ~/Documents/private ~/GoogleDrive/vault --interval 10m
gocryptfs-standalone pair list
gocryptfs-standalone sync documents        # one pair
gocryptfs-standalone sync                  # all pairs
gocryptfs-standalone daemon                # all pairs on changes and in their intervals until stopped
gocryptfs-standalone service install       # start "daemon" after each log in
gocryptfs-standalone service status
gocryptfs-standalone service uninstall
gocryptfs-standalone pair remove documents

Everything lives in configuration.json inside the configuration directory and can be edited by hand as well:

{
    "defaults": {
        "excludes": [".DS_Store", "._*", ".~lock.*#", "Thumbs.db", "desktop.ini", "~$*"],
        "interval": "10m",
        "trashDays": 30,
        "watch": true
    },
    "pairs": {
        "documents": {
            "plaintext": "/home/me/Documents/private",
            "vault": "/home/me/GoogleDrive/vault",
            "interval": "5m",
            "excludes": ["*.tmp", "build/"],
            "trashDays": 7,
            "watch": false,
            "password": "keychain",
            "config": "/home/me/vault.conf"
        }
    }
}

A pair's excludes are added to the default ones. config is optional and only needed for a configuration file outside of the vault (pair add --config). Intervals take seconds, minutes or hours (30s, 10m, 2h, at least 10 seconds). Password sources:

Credential stores used without any native module or admin rights:

• macOS: login keychain via security
• Linux: Secret Service (GNOME Keyring, KWallet, …) via secret-tool (package libsecret-tools or similar)
• Windows: DPAPI via PowerShell, the encrypted password is stored in credentials/<pair>.dpapi inside the configuration directory and can only be decrypted by the same user on the same machine

The daemon unlocks all vaults on start (so wrong passwords fail early), synchronizes every pair right away and afterwards in its interval. Runs never overlap and failures get retried in the next interval, a run blocked by a parallel sync of the same pair after 10 seconds. Only one daemon watches a pair at a time, another one stops right away (exit code 4). Pairs must not overlap: pair add, sync and daemon refuse configurations where a directory of one pair (plaintext or vault) is located inside one of another pair.

With "watch": true (default) the daemon additionally listens to file system events of both sides (FSEvents on macOS, inotify on Linux, change notifications on Windows) and synchronizes a pair 2 seconds after the last change, at the latest 30 seconds after the first one while changes keep coming. Changed entries still looking like after the last synchronization (e.g. written by it) do not trigger a run. Events only trigger a regular synchronization, so the interval stays as fallback for changes no event reports: cloud clients (e.g. files arriving in a Google Drive folder) and network or FUSE mounts often do not report everything. If watching fails (e.g. Linux' limit of inotify watches, fs.inotify.max_user_watches, is reached) the pair is synchronized in its interval only and watching is retried every 5 minutes. --no-watch disables watching for pair add or a single daemon run. service install registers it per user:

• macOS: launchd agent ~/Library/LaunchAgents/com.tsickert.gocryptfs-standalone.plist, logging to daemon.log in the configuration directory
• Linux: systemd user unit ~/.config/systemd/user/gocryptfs-standalone.service (log: journalctl --user -u gocryptfs-standalone, keep it running while logged out with loginctl enable-linger)
• Windows: command file in the user's startup folder, starting the daemon minimized and logging to daemon.log in the configuration directory

Password of single commands

The password is taken from the first available source:

1. --passfile <path> (first line of the file)
2. --extpass <command> (first line of the command's output)
3. Environment variable GOCRYPTFS_PASSWORD
4. Interactive prompt

Alternatively --masterkey <hex> unlocks the vault with its master key. A given master key is checked against existing vault content before anything gets encrypted with it.

Related projects

• gocryptfs defines the on-disk format implemented here.
• gocryptfs-inspect and gocryptfs-create-folder are Python tools decrypting files respectively creating vaults without FUSE.