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GUIDE

Encrypted file sharing is a process, not a label.

An encrypted upload has several stages: encrypting, transporting ciphertext, controlling access and eventually expiring or deleting it.

Updated 19 September 2026 · Product documentation

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1. Encrypt before transport

Authenticated encryption such as AES-GCM protects confidentiality and detects tampering when keys and nonces are handled correctly. Browser-side encryption can keep the application server from needing the plaintext file.

2. Transfer in chunks

Large encrypted files can be divided into chunks. This supports retry, progress reporting and bounded requests.

3. Control access

Storage still needs authorisation. Media access is protected by authenticated sessions, room matching, signed transfer tokens, expiry and quota controls.

4. Expire when appropriate

Expiry reduces the retention window. It cannot undo a copy already made by a recipient.

5. Remember the recipient

Once the recipient can open the file, they can potentially copy or photograph it. Application encryption cannot control the recipient's device.

A five-question check

  1. Is the file encrypted before storage?
  2. How is the key delivered?
  3. How is the recipient authorised?
  4. How long does ciphertext remain?
  5. What happens after expiry?
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