How to Use Your Bark Vault

This is a short guide to using the Bark Vault in Cypher Box app, a self-custodial Bitcoin and Lightning wallet built on the Ark protocol. It walks you through creating your vault, backing it up, recovering it, and keeping your funds safe as your lightning capsules refresh.

Your Bark Vault holds Bitcoin as lightning capsules (their technical name is VTXOs). This is not to be confused with onchain UTXO capsules that can be seen in your Hot or Cold storage vaults. Unlike UTXOs that come with specific shapes and colors that represent their size, VTXO lightning capsules with 4 colors from green to red so you can tell how urgently they need to be refreshed. Each capsule is a small pocket of Bitcoin on the Ark layer that spends fast and cheap via Lightning. The one thing that makes them different from ordinary Bitcoin: every lightning capsule has an expiry date and must be refreshed to stay alive. We chose to let users manually control their coins, as opposed to hiding this responsibility behind automated mechanics that may cause more harm and confusion than good in the long run. refreshing only happens while the Cypher Box app is open. The app watches your lightning capsules for you and sends reminders as expiry gets close (4 days, 2 days, then 24, 12, and 6 hours before), but if you never open it before a capsule expires, that balance can be lost forever.

Keeping your Bark capsules safe is easy: just open the app now and then, and especially when it nudges you. We will explore refresh habits in greater detail later in this guide.

Create your vault

Creating a vault walks you through the two things you must save:

Your seed phrase (12 words).
Your Bark backup file (.cbark).

Warning: Your seed words alone cannot bring your capsules back, so both pieces matter. You can also let the app keep your seed on the device behind Face ID / Touch ID for quick unlock later.

Back up (you need BOTH pieces, in TWO places)

The seed phrase and the .cbark file together are what actually restore your money.
Keep a local copy (the app saves the .cbark on your phone automatically; on iPhone it’s in Files, On My iPhone, Cypher Box) and a cloud copy (iCloud Drive on iPhone, Google Drive on Android).

Keep both copies because they cover different accidents: the local copy saves you if the cloud is offline, the cloud copy saves you if you lose or break your phone.

Fund your vault

Three ways to receive:

From another Bark user (a Bark address): instant and free.
Over Lightning (a Lightning invoice): the most common way. Money received this way lands as a short-life capsule (an “arkoor”), currently lasting only about 2-4 days, and it isn’t fully in your sole control until it’s refreshed. So decide right away:
- Keeping it? Refresh it now so it becomes a full, self-custodial capsule.
- Spending it soon? Leave it, no need to refresh.
On-chain (board): deposit Bitcoin, then board it in. On-chain top-ups arrive as long-life capsules (about a month), so no immediate action. There’s a minimum (around 50,000 sats); smaller on-chain deposits can’t be boarded.

The refresh habit

Refreshing gives a capsule a fresh full life (about a month) and usually finishes within 3 hours during which they become unspendable . A simple safe habit is:

Open the app every week or two and glance at your lightning capsules. Make sure they’re coloured green or at least yellow, not orange or red.
If any are getting close, let it refresh (or tap the reminder notification, which opens straight to your capsules with the refresh already running).
Give it up 3 hours, and come back to make sure the capsule have been refreshed successfully.

If a refresh gets stuck

Sometimes the Ark Service Provider (second.tech) that coordinates users’ Ark offchain balances with the Bitcoin network (doesn’t custody funds) has trouble and a refresh won’t complete. As a lightning capsule nears expiry the app warns you and can open a “Stuck refresh” screen. It first cancels the stuck attempt to unlock your funds, then lets you move them somewhere safe before the deadline:

Swap out to Strike or Coinos (fast and cheap, best for smaller amounts).
Send on-chain to your Hot Vault, Cold Vault, or any Bitcoin address.

Near expiry the goal is to get the money out, not to keep retrying.

Emergency Exit (your ultimate safety net)

Emergency Exit, in the vault Settings, pulls your entire Ark balance back on-chain without needing the server’s cooperation at all. It’s your guarantee that you can always get your money out. Know these:

It takes about 24 hours. Bitcoin enforces a roughly 24-hour wait, and once started it can’t be cancelled.
Start it at least a full day before your soonest capsule expires, because the exit transactions must confirm on-chain first. It is not a last-minute rescue.
Fund the fee reserve first. The exit pays on-chain miner fees from a separate on-chain wallet. The app gates it behind “Fund exit fees first” and tells you how much to add. Without it, the exit stalls.
Best for larger amounts, where the on-chain fee is worth paying. For small amounts, swapping to Strike or Coinos is cheaper. You pick a Hot Vault, Cold Vault, or external address as the destination.

Test before you trust it with a lot

Before keeping a large balance, do a practice recovery: back up, then restore from your seed + .cbark (same phone is basically Face ID unlock plus one tap; a new phone means typing the 12 words and loading the file). Confirm the balance comes back, then scale up.