Security Model

This page explains what protects your files and account when you use this client, what it keeps on your computer, and what it does not protect against. It is a summary for users. The details, with references to the code, are in the threat model. To report a vulnerability, see SECURITY.md.

This is an unofficial hobby project, not a Proton product. It has had no independent security audit. The source is open under the MIT license, so you can read and build all of it yourself.

Encryption

Proton Drive is end-to-end encrypted, and this client does not change that:

• Files are encrypted on this computer before they are uploaded, and decrypted on this computer after they are downloaded. Proton never receives your keys or the content of your files.
• The cryptography comes from the SDK, not from this client. The client uses proton-sdk and proton-drive-rs, a Rust port of Proton's official C# and TypeScript Drive SDKs. OpenPGP is done by the rPGP library. The client itself does not implement any encryption.
• Your password is not sent to Proton. Sign-in uses Proton's SRP protocol, which proves that you know the password without sending it.

What is kept on this computer

What	Where	Protected by
Session tokens and the key passphrases	The system keyring (Secret Service: GNOME Keyring, KWallet, KeePassXC)	The keyring's own encryption and your login
Your password	Nowhere	—
Cached files, thumbnails and changes waiting to upload	~/.cache/proton-drive-linux/content/	File modes only: not encrypted
File and folder names, the folder tree, the activity log	~/.local/state/proton-drive-linux/cache.db	File modes only: not encrypted
The SDK's metadata cache	~/.local/state/proton-drive-linux/sdk_cache.db	Encrypted with a key derived from your mailbox password
Settings	~/.config/proton-drive-linux/config.json	No secrets are stored here

The cache holds decrypted content so that files open fast and work offline. The client assumes that your disk is encrypted (LUKS, or an encrypted home directory). On an unencrypted disk, someone who has the powered-off computer can read the cached files and the names in your Drive.

Accounts with a separate mailbox password (two-password mode) are locked by default. Their key passphrases are kept in the kernel keyring for your login session only, and you unlock again after each login. Storing them in the system keyring is an opt-in.

Who can use the client

• The state, cache and config directories must belong to you and have mode 0700. The daemon checks this at every start and refuses to run otherwise.
• The control socket that the app, tray and pdfs use has mode 0600. Only your user account can connect to it.
• Any program that runs as your user can read, change and delete files in ~/ProtonDrive, the same as in any other folder you own. It is your Proton Drive, not a copy: a deleted file is moved to the Proton Drive trash, where you can restore it.

Network connections

The client connects only to:

• Proton, for the Drive and account API, and for the CAPTCHA page when Proton asks for one.
• OpenFreeMap, for the street map of Places in Photos, only if you turn it on in Preferences. It is off by default, because the tile server learns which parts of the world you look at. The default map is drawn from data shipped with the app.
• GitHub, once a day, to ask for the latest release, only if you turn on Check for updates in Preferences. It is off by default, because GitHub learns your IP address and, from the user agent, which version you run. Packages updated by a package manager (COPR, the AUR, Nix) do not offer the setting and never ask.

There is no telemetry and no analytics. The SDK can report timings of its own operations, and the client only writes them to its local log.

What this client does not protect against

• Malware running as your user. It can read the cache, connect to the control socket, and use your Drive through the mount, as it can with any data you have access to.
• Swap. Keys and decrypted data are in ordinary memory and can be written to swap. Use encrypted swap.
• The kernel page cache. File content read through the mount is cached by the kernel like any other file.

Packages

• The .rpm on the release page is signed with GPG.
• The COPR packages are built by Fedora's COPR service from the tagged source and the vendored crates of the release, and are signed with the COPR project's own key.
• The .deb and the .tar.gz are built by GitHub Actions from the tagged source, and are not signed.
• The AUR packages build from the tagged source or from main, or install the release binaries checked against their SHA-256 sums.
• The Nix flake builds from source. The binary cache on Cachix holds builds made by CI.