1. Select a file
Start by selecting a file from your device that you want to share with the recipient.
2. Set limitations (Optional)
You can improve the security of the share by setting limitations:
- Download limit: Set how many times the file can be downloaded before the link stops working.
- Expiration time: Set a time limit after which the file can no longer be downloaded.
3. Create and share link
Create the share link and copy it. You can forward the link via email or instant messenger, for example.
When browser encryption is enabled, send the share link and the separate encryption key through different channels. Do not add the key to the link address or URL parameters.
Privacy
Uploaded files are temporarily stored on the server until they expire or the download limit is reached. Browser encryption processes the file in 4 MiB AES-GCM chunks, so the whole file is not loaded into memory at once. The maximum size is 500 MiB.
The browser creates the encryption key and encrypts the file locally. The server stores the ciphertext and a SHA-256 verifier, not the raw AES key. On download, the browser sends only that verifier in an HTTPS header for access checking and decrypts the returned ciphertext locally. The verifier is treated as authorization data and is not added to the URL, analytics or application logs. The server can see the ciphertext and verifier but cannot use them to decrypt the file. A browser extension, malware or another person using the device may still see a key entered in the browser.