CryptStorage

Venomia CryptStorage (short: CryptStorage, formerly secdisk) is self-hosted end-to-end encrypted personal cloud storage. Files are encrypted on the user's own machine (gocryptfs format; cppcryptfs on Windows); the server stores only ciphertext. The user connects with one password and a USB key stick, and the encrypted volume appears as a normal folder or drive.

Status: pre-release, not independently audited. Do not use it for the only copy of data you cannot afford to lose. Read SECURITY.md first: it says what the design protects and what it does not (a malicious server cannot read files, but it can delete or roll them back, and it sees sizes and timing). The design is in docs/design-e2ee.md.

How it fits together

  user machine                              server
  ┌──────────────────┐   HTTPS   ┌─────────┐        ┌──────────┐  Unix socket  ┌─────────────┐
  │ cryptclient (Go) │──────────▶│ nginx   │───────▶│ api      │──────────────▶│ cryptdaemon │ cryptstorage
  │ encrypts/decrypts│  login    │ ├ webui │        │ (FastAPI)│  (HMAC auth)  │ SFTPGo users │
  │ + USB key stick  │           │ └ /api  │        └────┬─────┘               └──────┬──────┘
  │       │ SFTP/SSHFS│  SFTP port└─────────┘          MariaDB                         │
  └───────┴──────────┘◀──────────────────────────▶ SFTPGo (public-key SFTP, ciphertext only)

Directory	What it is
api/	FastAPI service: accounts, login, tokens, recovery verifier, escrow blob
cryptdaemon/	Daemon on the host: creates and removes the users of the SFTPGo storage service (REST API)
webui/	PHP web interface: account information only; the login key is derived in the browser
cryptclient/	Go client: setup, USB key stick, encryption, SSHFS mount (Linux, Windows 10+; macOS untested)
ansible/	Deployment: nginx + TLS, Docker (api, webui, db, SFTPGo), firewall, fail2ban, systemd
scripts/, docs/	Backup script, backup/restore guide, and the end-to-end design
tests/	pytest suite (see below)

Deploying

One fresh Ubuntu 24.04+ or Debian 12+ server (1 GB RAM is enough), a domain pointing to it, and Ansible on Linux, macOS or Windows WSL. Full steps: ansible/README.md.

cd ansible
ansible-galaxy collection install -r requirements.yml
./setup-files.sh                                     # copies the sources into the roles
cp inventory/hosts.yml inventory/my-hosts.yml
./generate-secrets.sh                                # real values for the CHANGE_ME placeholders
$EDITOR inventory/my-hosts.yml                       # server, domain, e-mail, secrets, SMTP
ansible-playbook -i inventory/my-hosts.yml site.yml

The playbook refuses to run with CHANGE_ME placeholders, and the API refuses to start without real secrets. Set recovery_policy (user, escrow or both) and, for escrow, escrow_public_key (scripts/escrow.py keygen). Set up backups before inviting users (docs/BACKUP.md).

Using it

Windows 10+ and Linux. On Windows the installer sets up the required components; then run cryptclient setup: it walks through account creation, e-mail confirmation, the USB stick, the storage and the recovery code (shown once) in one conversation. Afterwards cryptclient connect asks for your password, unlocks the key from the stick, and opens the encrypted storage as a folder or drive. The web UI shows account information only (login details, disk usage, two-factor). A forgotten password can only be recovered with the recovery code (or, if the operator enabled escrow, by the operator).

More in cryptclient/README.md and webui/README.md.

Requirements and design principles

• Two factors for every access. The password alone is never enough: access needs a second factor such as the USB key stick, a device-bound key or a phone one-time code (see docs/design-factors.md). Today the stick opens the storage, and the account login also needs an authenticator app code or a passkey. The SSH key is not a readable file. Ordinary SFTP clients are not a supported way in. This deters casual copying; the real protection is the factors together (see SECURITY.md).
• No file browsing in the web UI. It shows account information only: login details, disk usage, password change and similar.
• Supported client platforms: Windows 10 or newer and current Linux distributions. macOS builds but is untested and not supported in v0.1. Windows 7 and 8 are not supported.

Development

pip install -r requirements-dev.txt
python -m pytest -q             # unit tests, API <-> daemon smoke test, web UI against a stub API
python -m pyflakes api cryptdaemon tests
cd cryptclient && go vet ./... && go test ./...

The web UI tests need php on the PATH and are skipped otherwise. The client flows run against a real API, SFTPGo, sshfs and gocryptfs in CI, and on a real Windows machine (see docs/windows-testing.md). The production Ansible roles (nginx/TLS, fail2ban, UFW) are not exercised by CI: try them on a test server before relying on them.

Third-party software

The storage service is SFTPGo by Nicola Murino (AGPL-3.0, with additional attribution terms in its NOTICE). It runs unmodified as a separate service; its source is at the link above.

License

GNU Affero General Public License v3.0 only (AGPL-3.0-only), Copyright (c) 2026 Matti Mieskonen (@valveo).

You may use, modify and share CryptStorage for any purpose, including inside a company. If you change it and let others use the changed version, also over a network (for example by hosting it as a service), you must offer them the complete source code of your version under the same license.

If you want to use CryptStorage in a way the AGPL does not allow, for example a paid service or product without publishing your changes, contact the author through GitHub (@valveo) about a separate commercial license.

Versions published before 2026-10-25 were under the PolyForm Shield License 1.0.0.