Think about where your most sensitive financial documents live right now. A photo of your driver's license buried in your camera roll. Last year's tax return sitting in a shared cloud drive. A signed lease as an email attachment. Bank statements in your Downloads folder. Every one of those is a plain file that anyone with access to the device, the account, or the server can open.

That is the problem the Vault in Voice Money Manager was built to fix. It gives your IDs, statements, tax documents and contracts a single, private home — one that is zero-knowledge. In plain English: your files are locked on your own device before they ever leave it, and the only key that opens the lock is made from a passphrase that only you know. Not us, not our servers, not support. Even we can't read your documents.

What "zero-knowledge" actually means

Most cloud storage encrypts your files, but the company also holds the key — which means the company (or anyone who compromises it) can technically open your files. Zero-knowledge flips that. The key never exists on our side at all.

Here is the simple version of how it works under the hood:

• Your passphrase becomes a key. We stretch it into a strong encryption key using Argon2id — a deliberately slow, memory-hungry process that makes it enormously expensive for anyone to guess passphrases by brute force.
• Your file gets sealed. Each document is locked with XChaCha20-Poly1305, a modern, well-respected cipher. "Sealed" means it is both scrambled and tamper-evident — if a single byte is altered, it won't open.
• Only the sealed version travels. What leaves your device is already an unreadable blob. The key stays with you.

A helpful way to picture it: imagine a lockbox where the only key in existence is cut from your passphrase, on your device, at the moment you unlock it. We store the box. We never get a copy of the key.

Adding a document to your Vault

1. Open the Vault from your account and set a Vault passphrase the first time (choose something long and memorable — more on that below).
2. Tap Add document and pick a photo, PDF or scan — an ID, a statement, a tax slip, a contract.
3. Give it a clear name and, optionally, a category so it's easy to find later.
4. Save. The file is encrypted on your device with your passphrase-derived key, then the sealed version is stored. The original never leaves in readable form.
5. To view it again, unlock the Vault with your passphrase — the document is decrypted on your device just long enough for you to read it.

A concrete example

Say it's tax season and Maria needs to keep her T4, two bank statements, and a rental contract together. Today those are scattered across her email, her phone gallery, and a family cloud folder her sister can also see. She opens the Vault, adds all four documents, and names them plainly: "T4 2025," "Chequing statement — Jan," "Chequing statement — Feb," and "Apartment lease." Each is sealed on her phone as she saves it. Now they live in one private place. When her accountant asks for the lease, she unlocks the Vault, opens that one document, and shares it deliberately — instead of scrolling through a camera roll where it sat next to everything else.

The one rule: guard your passphrase

Because the key is made from your passphrase and lives only with you, there's an honest trade-off you need to understand: if you lose your passphrase, no one can recover your documents — not support, not us. There is no "forgot password" back door, and that's deliberate. A back door for you would be a back door for an attacker too.

So treat the passphrase with care:

• Make it long and unique — a short phrase of several unrelated words beats a single complex word.
• Write it down somewhere physically safe, or store it in a reputable password manager.
• Don't reuse a passphrase you already use elsewhere.

Once you've got the Vault set up, you can also open it on a big screen without weakening any of this — see how to open your vault on your computer securely.

FAQ

Can Voice Money Manager staff read my Vault documents? No. Files are encrypted on your device with a key derived from your passphrase, which we never receive. We only ever store sealed, unreadable versions, so even we can't open them.

What happens if I forget my passphrase? The documents can't be recovered by anyone, including support — that's the point of zero-knowledge. Keep your passphrase written down somewhere safe or in a password manager.

Is the Vault "hack-proof"? No honest product claims that. What the Vault guarantees is that your key never exists on our side, so a breach of our servers would expose only sealed blobs that can't be read without your passphrase.