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View & Decrypt

Documents are decrypted on your iPhone. The private key is used only inside Qpher's isolated key service and never reaches your device.

Open a document​

  1. Tap a document in your list
  2. On the document page, tap View

Qpher Vault shows the document with iOS Quick Look, which opens PDFs, images, Office documents, text files and most audio and video. Pinch to zoom and scroll.

Save a copy to your device​

Your own document: tap ⋮ → Save original. The first time, tap I Understand to accept the notice. Qpher Vault decrypts the document on your iPhone and opens the iOS share sheet, where you can save it to Files or send it on.

A saved copy is not encrypted

Once you save the decrypted file to your device, Qpher no longer protects that copy. The encrypted version stays in your vault.

A document shared with you (download permission): tap ⋮ → Save a copy. Qpher Vault decrypts it on your iPhone, encrypts it again with your own key and adds the copy to your Documents tab. The copy stays yours if the sender revokes the share.

How decryption works​

When you open a document, Qpher Vault:

  1. Downloads the encrypted file
  2. Sends the file key's KEM ciphertext to Qpher's isolated key service, which recovers the one-time shared secret with your private key and returns it over TLS
  3. Unwraps the file key on your iPhone and checks the file's header
  4. Decrypts the file on your iPhone and checks its SHA-256 hash
  5. Clears the file key and the shared secret from memory

View-only shares​

View-only: they can read it but not download it. Download: they can save a copy.