Device Sync: The Same Vault on iPhone and iPad
Add a photo on your iPhone and open it on your iPad, without a readable copy ever crossing the network. Vaultaire encrypts each change on the device that made it, and the other device merges the encrypted result.
Device Sync keeps one Vaultaire vault available on Apple devices signed in to the same iCloud account. It uses Vaultaire's encrypted iCloud backup as transport, keeps all sync bookkeeping inside the encrypted vault, and never turns your pattern into an account password.
How This Differs From Syncing Photos Through iCloud
iCloud Photos syncs your library. It is fast and it works, and the price is that the library is the unit: what one device holds, every device signed in to the account holds, and the contents are readable by the service that stores them.
Device Sync syncs a vault, not a library. The unit is one vault at a time, and you choose which vaults take part. What travels is a set of encrypted records that mean nothing without the key derived from your pattern. A photo in a synced vault does not appear in the Photos app on either device, does not appear in Memories or shared albums, and is not part of the library that a family member with access to your Mac can browse.
The two systems can run side by side. Turning on Device Sync for a vault changes nothing about iCloud Photos, and turning off iCloud Photos does not stop a vault from syncing.
How to Sync a Photo Vault Between iPhone and iPad
1. Turn on encrypted iCloud backup for that vault
Device Sync rides on encrypted iCloud backup, so that switch has to be on for the vault you want to sync. It is per vault, not global. A vault you never enable stays on one device and produces no cloud records at all.
2. Open the same vault on the second device
Sign the second device in to the same iCloud account, install Vaultaire, and draw the same pattern. The pattern regenerates the same key locally, which is what lets that device decrypt the records the first device wrote. Nothing is sent to us, and no account is created.
3. Let the devices converge
Sync runs when the app comes to the foreground and when iCloud pushes a change notification. Each device fetches new encrypted records, merges the change history, and writes the resulting vault state locally. A file added on one device shows up on the other after that cycle completes.
What the Merge Does When Both Devices Change Things
Sync systems break in the gap between two devices doing something at once. Vaultaire resolves that gap inside the encrypted vault, using rules chosen for a photo vault specifically.
Adds win over deletes that did not see them. If your iPad deletes a file while your iPhone is adding a different one offline, both intentions survive: the delete applies to what the iPad had actually observed, and the iPhone's new file is not swept away by it. A delete only removes a file from the other device once that device's history shows it had seen that file.
Identical files collapse. Save the same photo on both devices and the merge recognizes them as one entry rather than leaving you two copies to clean up. The duplicate encrypted chunks are collected and evicted by the same cleanup path that handles old backup versions.
The merge is order-independent. Running it twice, or running it on changes that arrive in a different order, produces the same vault. That is what lets both devices reach the same state without a server deciding who wins.
Device Sync is only for devices signed in to your own iCloud account. To give another person access to a vault, use Secure Sharing, which hands over a read-only copy through a one-time phrase and is a completely separate flow. There is no way to turn Device Sync into a shared vault, and no way for a sync peer to appear that you did not sign in yourself.
What iCloud Actually Stores
Every sync write is a record in one zone in your private iCloud database. Each record has a random UUID name, the same record type as every other record Vaultaire writes, and a padded size. File membership, which device added what, change counters, and deletion markers all live inside the encrypted payload.
This shape is deliberate. If sync records were named after their contents, or if each vault got its own zone, or if device identifiers appeared in the record schema, then the storage layer would reveal how many vaults you keep and how many devices you use, even without decrypting anything. Vaultaire keeps that structure inside the envelope, so the cloud view of a two-device user with several vaults looks like the cloud view of one device backing up more often.
What Apple can still see is ordinary service metadata: that records were written, roughly how large they are after padding, and when. That is the honest boundary. Vaultaire cannot hide the existence of network traffic, and it does not claim to.
When Photos Are Not Syncing Between iPhone and iPad
Sync stalls almost always come from one of a short list. Work down it in order.
Backup is off for that vault. Device Sync needs encrypted iCloud backup enabled for the specific vault, on both devices. Enabling it for one vault does nothing for the others.
The vault is not open. Sync work for a vault needs an active pattern-authenticated session. A locked device is not syncing that vault, by design.
The accounts differ. Both devices must be signed in to the same iCloud account with iCloud Drive available. A second Apple Account, however similar the pattern, produces two separate vaults that never meet.
iOS has not given the app time. Sync runs on foreground and on push. If the app has been closed on the receiving device, open it and give it a moment on a working connection.
The device was disconnected. If Disconnect This Device was used, that device keeps its local copy and stops exchanging changes until you turn sync back on.
The device was duress-wiped. After a duress unlock, Vaultaire isolates that device from sync on purpose, so a wipe is never republished to your other devices as an ordinary delete. Rejoining is explicit and needs the recovery phrase.
Control, Isolation, and Recovery
Disconnect This Device is local. It stops upload and download for the device in your hand, keeps the vault on it, and does not revoke peer devices or delete cloud backups. Removing the local data is a separate, deliberate action.
Duress isolation is the rule that protects the rest of your devices. Duress mode is local only: it wipes what is on that device, leaves the encrypted iCloud backup intact, and cuts that device out of sync. It will not pull hidden vault state back down on its own afterwards. You recover one vault at a time, on purpose, using that vault's recovery phrase.
Inside an open vault, settings show a count such as This device + 1 other device. They never show device names, identifiers, or anything about your other vaults, and they show nothing at all before a vault is open. A count of participating devices is useful to you; a list of device names would be a leak waiting to happen.
Keep the recovery phrase somewhere separate from your devices. If you lose the pattern and the phrase, no part of this system can reconstruct the key, and that includes us.
What Device Sync Does Not Do
It is not live collaboration. Two people editing the same vault at the same second is not the problem it solves, and the merge runs in cycles rather than keystrokes.
It does not sync across Apple Accounts, and it does not sync to Android, Windows, or the web. The transport is your private iCloud database, so the boundary of Device Sync is the boundary of your account.
It is not a substitute for a backup you control. Encrypted iCloud backup covers the loss of a device. Device Sync covers using two devices. They overlap, but the recovery phrase is what covers everything else.
Frequently Asked Questions
How do I sync private photos between my iPhone and iPad?
Turn on encrypted iCloud backup for the vault, then open that same vault with the same pattern on the second device signed in to the same iCloud account. The first device uploads encrypted records and the second one merges them.
Why are my photos not syncing between iPhone and iPad?
Check, in order: encrypted iCloud backup on for that vault on both devices, the vault open on the device you expect to sync, the same iCloud account on both, a working connection, and whether the device was disconnected or duress-wiped and has not rejoined.
Does Device Sync share a vault with another person?
No. It connects your own devices through one iCloud account. Secure Sharing is the separate read-only flow for another person.
Can Apple read a synced vault?
Vaultaire encrypts the vault before upload. Apple stores opaque records with random names and can observe service metadata such as size and timing, but does not receive readable vault files or your pattern.
Is sync immediate?
No. It is eventually consistent, running on app foreground and on iCloud push. Connectivity, iCloud availability, and the background time iOS grants the app all affect when a change lands.
What happens if I add photos on both devices while offline?
Both sets survive the merge. Adds win over deletes made by a device that had not yet seen the added file, and the same file added twice collapses to a single entry.
How do I stop syncing on one device?
Use Disconnect This Device in that vault's sync settings. It is local: the vault stays on the device, and your other devices and cloud backups are unaffected.
Keep Your Vault Within Reach
Use one encrypted vault on your Apple devices without handing anyone the key.
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