NullKey NullKey vs cloud-backed photo vaults
NullKey is an Android app that keeps private notes, documents and photos in an encrypted vault on the phone, with no sync and no account. Cloud-backed photo vaults keep a copy online. This page compares the two approaches, and it describes the type of app in general, not any one product.
The description of cloud-backed photo vaults is general, because features vary between apps. NullKey facts come from the app itself and the sources below, and were last reviewed on 10 November 2026. Spot something out of date? Email hello@alvento.uk.
Feature comparison
Scroll the table horizontally to see both options.
| Point | NullKey | cloud-backed photo vaults |
|---|---|---|
| Offers cloud backup or sync | No app-run sync or cloud backup. The current app declares no internet permission. You choose an available destination for an encrypted backup with Android's document picker. | Yes, by definition. Files or a backup are kept online; storage and access arrangements vary by app. |
| Needs an account or sign-in to use | No. There is no account. | Typically yes. An account or sign-in is how the online copy is tied to you. |
| Has a way back in if you forget the unlock secret | A recovery key that you save yourself. There is no account reset. | Varies by app. Check how a forgotten code or password is handled. |
| Encrypts the stored files on the device | Yes. Contents use AES-256-GCM with a separate random key for each item. Argon2id turns your passphrase into a key that protects the vault master key. | Varies by app. Check whether files are encrypted before they leave the phone. |
| Lets you export or back up the vault yourself | Yes. Whole-vault encrypted backup with a read-back check; readable export of single items. | Varies by app. Some let you export a copy yourself and some rely on the online copy. |
| Stores notes and documents, not only photos and videos | Yes. Private notes, documents and photos. | Varies by app. Some focus mainly on photos and videos. |
| Shows ads | No ads. | Varies by app. Some have a free tier and show ads there. |
| Has in-app purchases or a paid tier | One optional one-time unlock. No subscription. | Varies by app. Some have a free tier and a paid tier. |
The honest case for cloud-backed photo vaults
A cloud-backed vault may suit a reader who wants the vault to survive a lost or broken phone without managing backup files. An online copy may help with recovery after a phone is lost; check the app's supported devices and restore process. NullKey has no sync, and a recovery key alone cannot restore files from a lost phone. It needs a saved encrypted backup and the passphrase or recovery key that belongs to it.
Some apps also sync across devices, which may suit a reader who wants the same vault on more than one phone. NullKey runs on Android 12L or later and has no sync between phones. A backup can be restored into an empty vault on a new phone with the passphrase or recovery key that belongs to it.
Where the files live
In a cloud-backed vault, the files or a backup are held online. That can provide a copy after a phone is lost, and it also means a copy exists outside your phone.
The vault is stored on your phone. NullKey has no sync and the current app declares no internet permission, so it does not send files to a server itself. You choose where an encrypted backup goes, and that destination's own rules apply.
Accounts and getting back in
Because the online copy is tied to you, apps in this category may ask for an account or sign-in, and a forgotten code may be reset through that account, for example by email.
NullKey has no account. If you forget your passphrase, a recovery key that you save yourself opens the vault. Nobody at Alvento can reset it for you.
Encryption, backups and what else is stored
Whether files are encrypted before they leave the phone varies by app, so check the description of any app you consider. Some in this category focus mainly on photos and videos.
NullKey encrypts each item with AES-256-GCM using a separate random key, stores notes and documents as well as photos, and makes a whole-vault encrypted backup with a read-back check.
Bottom line
Choose a cloud-backed photo vault if you want an online copy, and read how it handles several devices and how it encrypts files before they leave your phone. Choose NullKey if you are on Android 12L or later and want an encrypted vault kept locally without sync, with no account and a backup file you control, accepting that restoring after a lost phone needs a backup you saved and its matching passphrase or recovery key.
References
- https://alvento.uk/nullkey/security/ (fetched 10 November 2026)
- https://play.google.com/store/apps/details?id=uk.alvento.nullkeyapp&hl=en_GB (fetched 10 November 2026)
Frequently asked questions
Does NullKey back up to the cloud by itself?
No. NullKey has no sync and the current app declares no internet permission, so it does not send files to a server itself. You choose an available destination for an encrypted backup with Android's document picker.
Do I need an account to use NullKey?
No. There is no account. If you forget your passphrase, the recovery key that you saved opens the vault.
Does NullKey store more than photos?
Yes. NullKey keeps private notes, documents and photos in the same vault. Photos and notes open inside the app, and other files open through a readable export outside the vault's protection.
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