Stronger by Design: OWL and Proton Drive
This page compares OWL with Proton Drive one dimension at a time, using each company's own published documentation. On the design, OWL's documentation describes protections Proton's does not: encrypted folder structure, encrypted timestamps and original sizes, a server you can run yourself or air-gapped, a Linux desktop client, signed update verification, and a hybrid post-quantum key wrap. On the record, Proton is ahead: open-source clients, published independent audits, and a SOC 2 Type II attestation. OWL has none of those yet. Both columns are on this page.
1. What the server cannot read
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| File contents | Yes, encrypted on your device with AES-256. In client-side decryption the server stores ciphertext and wrapped keys without a usable content key. Privacy policy §4 | Yes. Keys and passphrases are generated on the client and reach the server only in encrypted form. Proton security model |
| File and folder names | Yes, encrypted inside authenticated catalog pages the server cannot open. Cryptography §5 | Yes. Names are encrypted with the parent folder's node key. Proton security model |
| Folder structure (which folder holds which file) | Yes. Directory membership and version manifests are inside the encrypted catalog pages; the server does not receive the page keys. Cryptography §5 | No. Each entry's location is stored as a reference to its parent entry; names are encrypted, the parent link is not. Proton security model |
| Original file size | Yes. Exact original sizes are encrypted. The server sees ciphertext lengths, and padding reduces size precision according to the selected settings. Cryptography §5 | No. Proton stores the size of the encrypted file, and its support FAQ says file size is not encrypted. One marketing page says sizes are encrypted; the policy and FAQ say otherwise. Drive privacy policy, Drive FAQ |
| Creation and modification times | Yes. Source timestamps are encrypted; server operation times remain service records. Cryptography §5 | No. "We do have access to file/folder creation and modification times." Drive FAQ |
| Thumbnails and previews | Yes. Private previews are generated and encrypted on your device. Privacy policy §3 | Yes. Thumbnail previews are end-to-end encrypted. Drive privacy policy |
| Descriptions, categories, file types | Yes, encrypted in the catalog pages. Cryptography §5 | Proton Drive documents no description or category fields. Extensions are part of the encrypted name. |
| What the server does see | Account identity, who shares what with whom, permission levels and expiry dates, chat sender and membership, IP addresses and request logs, billed storage and ciphertext lengths. Privacy policy §4 | Timestamps, permissions, the uploader's username and the encrypted file size, plus account and connection records under Proton's privacy policy. Drive FAQ, Drive privacy policy |
Both services hold the sharing graph and connection records in the clear. The difference is the catalog: OWL encrypts folder structure, original sizes and source timestamps; Proton's documentation says its server can read those.
2. Defaults and who else can read
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Default protection | Strictest by default. Client-side encryption with keys only you hold applies from the first file you upload. The OWL Promise | End-to-end encryption applies to all Drive files. No other storage mode is documented. Drive security |
| A provider-readable mode | One exists, and it is off unless you choose it. Server-side decryption (SSD) gives the server a usable key for one requested delivery. OWL asks in plain language and waits for your typed yes. Cryptography §3, The OWL Promise | Not found. Proton documents no server-side decryption mode for Drive files. |
| Can an administrator read a member's private files? | None documented. With full database access the operator holds ciphertext only, including on a self-hosted server. Privacy policy §4 | On business plans, yes. An organization administrator can sign in to a member's account and view, open and download files, and this cannot be disabled by the member. The key is held by the organization, not by Proton. Admin access, Organization key |
| Public publishing | Readable by design. A public link stores a usable unlock secret with the server. Privacy policy §4 | Readable by anyone with the link. Shareable links |
OWL offers a mode Proton does not, and that mode trusts the provider. It exists for deliveries that need server-side processing. If you never turn it on, the server never receives a usable content key.
3. Sign-in and recovery
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Password handling | The web sign-in flow supports OPAQUE, so the password stays on your device. The private-key envelope is encrypted locally with PBKDF2-HMAC-SHA-256 (600,000 iterations) and AES-256-GCM. Cryptography §4 | Keys are generated on the client under the account password. Proton's sign-in protocol is documented on its account pages, which this comparison did not cover. Proton security model |
| Recovery that keeps the boundary | A 160-bit random recovery key you save yourself. The server stores only the encrypted envelope. An emailed reset code authorizes retrieval and cannot decrypt it. Cryptography §3 | A 12-word recovery phrase, or a recovery file, unlocks encrypted data after a reset. A trusted web browser can also keep an encrypted backup keychain. Recovery methods |
| Email or phone recovery | Authorizes retrieval of the envelope only. It does not decrypt anything. Cryptography §3 | Restores the account only. After an email or SMS reset "you might not be able to access your data." Recovering encrypted data |
| If password, recovery key and devices are all lost | NDEVR cannot reconstruct the private key. Product security | Proton cannot restore the encrypted data. Recovering encrypted data |
Both designs keep recovery in the user's hands and both say plainly that losing everything means losing the data. Neither is stronger here.
4. Keys, algorithms and post-quantum
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Content cipher | AES-256. Current private files use authenticated AES-256-GCM, including segmented formats for streaming. Older AES-256-CBC files remain until migrated. Cryptography §1 | Per-file node keys. Files are encrypted in blocks of up to 4 MB. Proton security model |
| Key wrapping to recipients | ECIES over NIST P-256 with HKDF-SHA256 and AES-256-GCM. Cryptography §2 | Share passphrases are encrypted to the user's address key; node passphrases to the parent node key. Proton security model |
| Post-quantum key establishment | Implemented. A hybrid ML-KEM-768 and P-256 construction (HPKE, HKDF-SHA256, AES-256-GCM) wraps content keys in the native, browser and command-line clients. Hybrid HTTPS is live. As of October 22, 2026, enrollment was limited to controlled test accounts and historical keys had not been rewrapped. Post-quantum encryption in OWL | Not found for Drive. Proton's post-quantum protection applies to new Proton Mail emails. Drive apps appear only as minimum-version prerequisites; the Drive roadmap lists no post-quantum item. Mail post-quantum, Drive roadmap |
| Validated module | No. OWL uses approved algorithm families and does not claim FIPS 140 validation. Cryptography §7 | Not compared. |
OWL's post-quantum wrap is a design advantage with a restricted rollout. The page it links to states which accounts it covers and which it does not.
5. Where it runs
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Run it on your own hardware | Yes. OWL Server runs on your hardware, your network and your storage, including air-gapped. OWL Server | No. Files are stored on servers Proton owns and operates in Switzerland, Germany and Norway. No server component is published. File storage |
| Linux desktop client | Yes. OWL Nest lists Windows, macOS and Linux, mounts the drive in the file manager and syncs folders. About OWL | No desktop app as of October 2026. The Drive command-line tool runs on Linux. Proton says it is working towards a beta whose first release will likely be a headless daemon, with no date. Autumn and winter roadmaps, Drive CLI |
| Company and law | NDEVR, LLC, Oakland City, Indiana, USA. The hosted service runs on Amazon Web Services. Product security, Privacy policy §7 | Proton AG, Geneva. Governed by Swiss law. Terms |
Which jurisdiction matters depends on your threat model. Self-hosting removes the question for OWL: the server is yours.
6. Updates, supply chain and disclosure
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Signed updates | Yes. The client verifies an Ed25519 signature on the update manifest against a key pinned in the client, and the manifest binds the SHA-256 of the installer. Secure development §2 | Partly documented. Android signing-certificate hashes are published and the CLI download lists SHA-512 checksums. No update-signature verification is documented for the Windows or macOS apps on the pages checked. Verify APKs, Drive CLI downloads |
| Software bill of materials | Yes. A CycloneDX SBOM is maintained per release and available on request. Secure development §1 | Not compared. |
| Trackers and third-party calls | None. No advertising or analytics trackers, and the web client makes no third-party network calls by default. Secure development §4 | The website uses self-developed, locally hosted analytics. Native apps may use analytics software and crash reporting. Proton privacy policy |
| Vulnerability disclosure | Published policy and security.txt. Acknowledgement within 3 business days, assessment within 10, coordinated disclosure within 90 days, safe harbor, public advisories. No monetary bounty. Disclosure policy | Published policy. Acknowledgement within 5 business days, a 120-day embargo, safe harbor, and a bug bounty of up to USD 100,000. Bug bounty, Disclosure |
| Security support period | At least 5 years from the date OWL is placed on the EU market. Product security | Not compared. |
Proton pays researchers; OWL does not yet. OWL documents update-signature verification for its desktop clients; Proton's desktop pages do not.
7. The record: what an outside party has checked
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Open-source clients | No. OWL's client and server source is not published. | Yes. The Android, iOS, Windows, macOS and web Drive apps are published under GPL-3.0; the SDKs under MIT. Drive open source, ProtonDriveApps on GitHub |
| Independent security audit | No. The OWASP Top 10 review is a self-assessment; an independent audit has not been performed. Compliance | Yes. Securitum audited the iOS and Android apps, with reports published in March 2023. A newer report is linked from Proton's security page without a stated scope or date. No desktop or web Drive audit was found. Mobile audit, Drive security |
| Certifications | None held. SOC 2 Type II is planned and ISO/IEC 27001 is under evaluation. Certifications roadmap | SOC 2 Type II completed July 2025, verified by Schellman. ISO 27001 is claimed on business pages without a stated certifying body, date or scope on the pages checked. Pass security, Business FAQ |
| Published self-assessments | Cryptography, OWASP Top 10, CSA STAR Level 1, NIST CSF, SLSA and secure development, each marked as self-assessed. Compliance | Not compared. |
| Time in public service | Open beta in 2026. OWL has not yet been placed on the EU market. Compliance | Proton's Drive security model post dates from September 2022 and the service has operated publicly since. Proton security model |
This is the table that should decide whether you trust the first six. Proton leads on every row of it. OWL's self-assessments are public and specific, and they are still our own word. The certifications roadmap lists what we are working toward and states that we will claim a certification only once it has been awarded.
8. Sharing, documents and AI
| Dimension | NDEVR OWL | Proton Drive |
|---|---|---|
| Share links | Current private links support expiry, revocation and optional sign-in. The unlock capability stays in the URL fragment, which browsers do not send to the server; the client sends a derived lookup identifier, verifies the signed grant and decrypts locally. Cryptography §6, Trust boundaries | Password, expiry and revocation; recipients need no account. Proton's server knows the URL but never receives the password. Shareable links, Proton security model |
| After revocation | Future delivery stops. Copies a recipient already saved remain. About OWL | Anyone using the link loses access immediately. Shareable links |
| Documents and spreadsheets | OWL Documents and Spreadsheets are in beta and save to the encrypted drive. This page makes no claim about the collaboration channel. About OWL | Proton Docs and Sheets are documented as end-to-end encrypted, including live collaboration. Document editor |
| AI and your files | Optional, off unless you use it. Prompts and images you submit are relayed to a model; files, identity and email are not sent; nothing is retained beyond the request; no training. Privacy policy §6 | Optional. Scribe is a Mail feature. Lumo sees a Drive file only when you add it to a chat and deletes it after the response. Lumo and Drive |
Both services keep AI off your files unless you hand a file over. Both still depend on trusted client software and recipient devices.
9. What would change this page
- An independent review of OWL's encryption design and clients. The record table changes the day a report is published.
- SOC 2 Type II, listed as planned on the certifications roadmap.
- General enrollment of the post-quantum key wrap and rewrapping of historical keys, tracked on the post-quantum page.
- A Proton Drive Linux desktop app, a Drive post-quantum rollout, or a published Drive audit with scope and date. We will update the Proton column when Proton's pages do.
Rows change only with a link to the page that changed. The retrieval date at the top of this page moves with each correction.