CipherFS
In development · unreleased · wire format 1

Your data, yours alone

Still keeping your files as they are on a cloud drive, an external disk or a NAS? Not any more. CipherFS encrypts and syncs in one go: your files move between your computers, disks, NAS and cloud drives on their own, and every one of those places holds nothing but scrambled data. Only you, with your password, can open them.

CipherFS is open-source software that runs on your own devices, not a cloud service. No account to create, no provider to depend on. Your data lives on your own disk, NAS or the cloud drive you already have, and syncs only between your own devices.

What you see, what is actually stored

My files

docs/
  contract-2026.pdf        2 versions
  notes.md                 edited on two devices
photos/
  2026-09/IMG_4471.heic    fetched when opened
projects/cipherfs/
  README.md
trash: old-drafts/ (14 files)

What the cloud drive, S3 bucket or disk actually holds

v/0a3kq7…
s/7q2dm4…
i/ed25519-d7a1…/0000000000000412-b3-9f3c…-18204
i/ed25519-2b90…/0000000000000098-b3-71e0…-6112
p/ed25519-d7a1…/0000000000000007/b3-3f8a…-6291456
p/ed25519-2b90…/0000000000000003/b3-c2d4…-5833728
r/b3-e41b…-b3-77c0…-2097152
What it is for

Your files should fit your life

01

Passports, contracts and family photos: backed up to the cloud, without the privacy worry

A cloud drive is convenient, but the company running it can see what you put there. CipherFS stores every file name and all content encrypted. The keys stay on your devices, and the drive holds nothing but scrambled data. The same goes for a NAS or a rented server.

passport.pdf
contract.pdf
family-photo.heic
Names and contents all encrypted
What the cloud drive stores
Keys stay on your devices
02

Laptop, desktop and cloud drive, kept in sync automatically

Install it on several devices and they keep each other in sync: laptop, desktop and cloud drive, with no manual backups. If a disk dies or the laptop is lost, the data is still there.

Your file library
Laptop In sync
Desktop In sync
Cloud drive In sync
03

Your laptop has 512 GB. Your cloud drive has 5 TB.

When the disk fills up, you no longer delete things to make room. Files you rarely use go to the cloud drive; your laptop keeps only the listing, they still appear in place, and opening one fetches it. Pin the folders you use every day and they work offline too. Everything on the drive is ciphertext, however large the library grows.

On your laptop512 GBPinned folders + recently opened files
On your cloud drive5 TBEverything else, encrypted
04

You overwrote a document, or deleted the wrong folder

Every save is a new version. Go back to yesterday’s document, or take a whole folder out of the trash; if two devices changed the same file, both versions are kept.

contract.pdf
  1. Today 14:02current
  2. Yesterday 18:40restore
  3. 12 Octrestore
Trash: old-drafts/ (14 files)Kept for a year, then 30 more days to change your mind

Travelling without reliable internet

Pin the folders you will need before you leave and they open on the plane as usual.

Moving to a new computer

Confirm it from the old one and it joins; you see the whole library at once and fetch content as you need it.

A computer goes in for repair, gets lost, or a disk is left on a train

What is on the machine or the disk is ciphertext; without the password it does not open. A lost device can be revoked from another one and never receives anything new.

Several people share the same files

Add the family’s or the team’s devices to one library and everyone works on the same files. Anything not meant for everyone goes in a separate library.

Switching cloud providers, or wiping an old disk

CipherFS shows where every file has a copy. Once the new place holds everything, remove the old one.

No cloud service at all

Connect two computers directly, or carry an encrypted disk between them. Nothing leaves your home.

Features and roadmap

What it does, and what is still missing

CipherFS is not released yet; the storage format is frozen. The roadmap has the detail and the requirements the target.

FeatureWhat it meansStatus
Core
End-to-end encryptionFile names and contents are stored encrypted; the keys stay on your devices.Available
Verified readsEvery read is checked: correct content or an explicit error, never damaged data.Available
History and trashEvery save is a version, deleted files wait in the trash, and concurrent edits keep both versions.Available
Fetch on demandA device can keep only what it uses and fetch the rest when opened; pinned folders work offline.Available
Large and small filesOnly changed blocks are uploaded, small files are bundled, and interrupted transfers resume.Available
Copy locationsSee which devices and storage hold a copy of each file before retiring a disk.Available
Protected deletionNo single device can delete from storage, so a mistake or ransomware cannot remove your copies.Available
Access recordWho touched which file, when, on which device; stored encrypted and never editable.Available
Device managementAdd a device by confirming on an old one, revoke a lost one, recover with the recovery key.Available
Shared librariesFamily or team devices join one library and work on the same files.Available
Export any timeEvery library carries a format description and a stand-alone recovery script, and exports to a plain folder.Available
People and rolesEach person joins with their own devices as read-write, read-only or admin; removing a person revokes all their devices.Planned
Scale acceptanceA million files, 1 TB, a 100 GB file and ten devices, measured against the published budget.Planned
File-system metadataPermissions, owners, xattrs, ACLs and hard links are not preserved.Not planned
Sync and storage
Automatic syncDevices keep each other up to date through storage, and need not be online at the same time.Available
Direct device-to-device syncTwo devices on the same network, or through a relay, sync directly with no storage in between.Available
Local disk, NAS and cloud-drive folders as storageAny folder can be a store: a local disk, a NAS share or the sync folder of a cloud drive.Available
S3 storageAny S3-compatible object storage works as a store.Available
WebDAV storageA WebDAV server works as a store.Available
Cloud drives by APIOneDrive, Dropbox and Google Drive without their desktop clients.Planned
Storage across several disksOne store spread over several disks, each file whole on as many of them as you choose.Planned
A trusted serverStores and relays only ever see ciphertext.Not planned
Command line and mount
Command lineEverything is available from the cipherfs command: vaults, files, stores, devices, history, trash, export and mount.Available
Mounted disk on macOS and LinuxThe library appears as a disk in Finder or the file manager, with content fetched when opened.Available
WindowsThe command line and libraries work; there is no mounted disk, and transparent access will come through Windows Cloud Files.In progress
A Windows file-system driverNo WinFsp driver and no WebDAV service; Windows transparent access is Cloud Files only.Not planned
Desktop app
Desktop appThe desktop app runs; its management panels, native uploads and downloads and vault selection are being completed.In progress
Desktop integrationSystem file providers, tray, autostart, biometric unlock, installers and updates.Planned
Phones
Phone appsAndroid and iOS apps that hold part of the library and fetch on demand.Planned
Servers and applications
Server serviceOne process holds a vault on a server, unlocks without a person present and puts the keys away when idle.Available
HTTP APIA local HTTP/JSON API with exact write receipts and streaming reads and writes.Available
S3 endpoint for applicationsAn application that already speaks S3 reads and writes through CipherFS without touching the keys.Available
Libraries and bindings
Rust libraryRust applications use the vault directly, with streaming reads and writes and background sync.Available
C, Python and Go bindingsThe same operations from C, Python and Go: files, byte ranges, streaming, recovery keys, pins, stores, devices and sync.Available
For developers

For your applications and servers

05

Your application already knows how to use S3

Point it at CipherFS’s S3 endpoint. A separate CipherFS process encrypts and syncs; the application uses its own credentials and never sees the keys. Each write can wait until it is stored locally, in the bucket, or on several devices.

Your applicationS3 / API
Read / write
CipherFS vaultHolds keys · encrypts · syncs
S3WebDAVNASDisk
06

A 40 GB video, a hundred thousand small files, a few edits a day

Large files are split into blocks; edit one part and only the changed blocks are uploaded. Small files travel bundled into objects of a few megabytes instead of one upload each. An interrupted transfer resumes where it stopped. All automatic, nothing to tune.

video.mov · 40 GBOnly the changed blocks are uploaded
Thousands of small filesBundled into a few objects
An interrupted transfer continues where it stopped

A server job saves files while you are asleep

Exports, reports and archives write through the API. The service unlocks from a key file or a keychain, with nobody typing a password.

A Rust core with a command line, a FUSE mount, a desktop app and C, Python and Go bindings. cipherfs serve holds a vault on a server and offers a local API and an S3 front door to applications. The architecture, the storage format, the algorithms and the Rust API are in the docs; the code is on GitHub.