Security & Zero-Knowledge Verification
How to independently verify that PdfWatch never sees your documents.
1. How It Works
Explain the zero-knowledge model:
You encrypt your PDF in your browser before it leaves your device
The encryption key exists only in the URL hash fragment (#key)
The hash fragment is never sent to our servers (browser behavior)
We store only the encrypted blob — unreadable without the key
Even our database administrators cannot read your files
2. How to Verify This Yourself
Open browser DevTools (F12) → Network tab
Upload a PDF on PdfWatch
Watch the network requests — you will see the file uploaded as an encrypted .enc blob, not a readable PDF
Open the share link. Inspect the URL — the decryption key is after the # symbol. This fragment never appears in Network tab requests to our server.
Go to the Network tab while viewing a document. You will see the encrypted blob downloaded and decrypted entirely in your browser — no plaintext ever sent to PdfWatch servers.
3. Inspect Our Encryption
We use AES-256-GCM encryption via the Web Crypto API
Key derivation uses PBKDF2 with 600,000 iterations
All encryption/decryption happens in your browser
Link to MDN Web Crypto API: https://developer.mozilla.org/en-US/docs/Web/API/Web_Crypto_API
Link to our open approach: The encryption key is in the URL fragment — if you lose the link, the file is permanently inaccessible to everyone including us.
4. What We Do Store
Encrypted file blob (unreadable without key)
Encrypted filename (unreadable without vault key)
View analytics: country, device type, browser, timestamps
Hashed IP addresses (one-way hash, cannot be reversed)
No original filename, no plaintext content, no decryption keys
Report a Security Issue
We take security seriously and aim to respond within 48 hours.
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