Secure Vault logo Secure Vault
Coming soon
Tour & user guide - v1.0

A vault for the files you would not want anyone scrolling past.

Secure Vault streams photos, videos, PDFs and any other file through AES-256-GCM into storage only it can read, and opens them again only for your passcode or fingerprint. It has no internet permission at all - not restricted, not unused: absent. This page is the whole product: a five-stop tour, then a reference for the details.

Coming soon to Google Play Email us to hear when it lands · Android 8.0+ · 3-day trial, then ₹201 once
Encryption
AES-256-GCM
Internet permission
None at all
Vault size
Up to 10 GB
Accounts
None needed
The tour

Five stops, from an empty vault to a backup you can survive on.

Secure Vault is a small app doing one thing carefully. Work through these five and you have seen all of it.

1Passcode

Set a passcode

The one thing standing between the files and everyone else.

  • Typed on the app's own keypad - never the system keyboard, which could be a third-party one with its own ideas.
  • Turn on fingerprint or face unlock afterwards for a faster way in. The passcode always keeps working.
  • Nothing is stored to check it against. The passcode is correct when it decrypts the vault key - see the keys.
  • There is no reset, no email recovery and no support back door. That is the point, and the app says so before you rely on it.
2My Vault

My Vault

Tap + to add photos, videos, or any files at all.

  • Files are picked through Android's own picker and streamed through AES-256-GCM in 64 KiB chunks into the app's private storage - a multi-gigabyte video never has to fit in memory.
  • Progress is shown byte by byte, not file by file, so a large import does not look stuck.
  • Once the copies are in, Secure Vault offers to delete the originals so only the locked copy remains - and says plainly that it cannot reach copies in Google Photos or another cloud backup.
  • File and folder names are encrypted too. Someone reading the app's storage sees opaque blobs, not "passport.pdf".
  • Folders (one level), multi-select, search and sort. Up to 10 GB.
3Viewing

Open it without letting it out

Viewing a file never writes the plaintext to disk.

  • Photos of any size, with EXIF orientation, pinch zoom and deep zoom on a 50 MP image - only the chunks on screen are decrypted.
  • Video and audio stream straight out of the encrypted file. PDFs page through, text opens inline.
  • Swipe between files; thumbnails are cached in memory and wiped the moment the vault locks.
  • Open with or Share hands a copy to another app - the one case that does create an unencrypted file. It is confirmed with a warning first, and the temporary copy is wiped on lock, on leaving the viewer and at next start.
4Backup

Back up the vault

Your protection if the phone is lost, reset, or the app is removed.

  • Writes one encrypted file containing everything, wherever you choose: Google Drive, an SD card, a computer.
  • Locked with a separate backup password - your passcode is not used, and not needed to restore.
  • The app is blunt about the consequence: forget that password and the backup can never be opened, by you or by anyone. Write it down somewhere safe.
  • Restore reads it into a fresh vault on any phone. Settings shows when the last backup was made, and says so when there has never been one.
5Settings & Reports

Settings & Reports

What the vault is doing, and everything you can change about it.

  • Reports - a security check-up and storage use: which protections are on, wrong passcodes in the last 7 days, recent unlocks, space used by file type, largest files.
  • Change passcode, biometric unlock, the lockout duration, the opt-in intruder photo.
  • Failed attempts - what was typed, when, and the photo if enabled.
  • Appearance and the octopus companion; animations Full, Reduced or Off.
  • Erase vault - schedules a permanent wipe 24 hours out, cancelled by any unlock.
!

Make a backup early. Secure Vault genuinely cannot recover a vault - not the passcode, not the files. If the phone is lost or reset and there is no backup file, the contents are gone. That is what "only you can open it" costs.

The guide

Reference, by topic.

Everything from the tour in more detail, plus what a file vault owes you in writing: how the keys are built, what the app protects against, and what it does not.

Getting started

First run

Four steps, and the fourth is the one people skip and regret.

1. Set a passcode
Typed on the app's own keypad. It is not stored anywhere, so choose something you will not lose - there is no reset.
2. Add your first files
Tap + and pick them through Android's file picker. They are encrypted as they are copied in, then Secure Vault offers to delete the originals.
3. Turn on fingerprint
Optional, in Settings. Faster than the passcode, and the passcode keeps working alongside it.
4. Make a backup
One encrypted file, its own password, saved anywhere you like. Do this before you delete originals you care about, not after.

The keys

Under the hood

The heart of the product, in five lines. Worth reading once, because it explains both why the files are safe and why a forgotten passcode is final.

The vault key
A random 256-bit AES key. Every file in the vault is encrypted under a key derived from it, one key per file.
Wrapped by your passcode
The vault key is wrapped by a key derived from your passcode with Argon2id (32 MiB, memory-hard), so each guess costs real time and memory.
Wrapped again by the phone
That bundle is wrapped by a non-exportable Android Keystore key, in secure hardware where the phone has it. On Android 15 and later, that key only works while the phone itself is unlocked - so code running as the app on a locked phone cannot touch it.
No stored password hash
The passcode is correct exactly when the wrapped key's authentication tag verifies. There is nothing to compare against, and so nothing to steal or reset.
Biometrics
A second wrapped copy under a fingerprint-bound Keystore key, which Android invalidates if fingerprints are re-enrolled. The passcode copy is the source of truth, so a biometric change can never cost you the vault.
In memory only while open
Locking zeroes the key in memory, closes every open reader, and wipes decrypted temporary files and the thumbnail cache.
i

Vaults created by older versions used PBKDF2. They are upgraded to Argon2id at the next correct passcode: the new copy is built, test-decrypted and swapped in atomically, and any failure keeps the old one. Old vaults stay readable forever.

Adding files

Import
Any file type
Photos, videos, audio, PDFs, documents, archives - the vault does not care what is inside.
Chunked encryption
Each file is written as a stream of 64 KiB chunks, each with its own authentication tag. The chunk index is bound into the tag, which is what makes reordering, splicing or truncating an encrypted file detectable rather than merely unlikely.
Large files
Up to 2 GB per file during the trial, 10 GB once purchased, and 10 GB for the vault overall. Progress is reported in bytes, so a big video shows real movement.
The originals
After a successful import, Secure Vault offers to delete them so only the locked copy remains. It tells you what it cannot do: reach copies already in Google Photos or another cloud backup. Remove those in that app.
If something goes wrong
Files that are too large, unreadable, or that do not fit are skipped and counted, not silently dropped. If the vault locks mid-import, it stops and tells you how many made it in.
Encrypted names
File and folder names are encrypted under the vault key. Sizes, dates and file types are not - that is a stated limitation, not an oversight.

Viewing files

In-app

The reason the vault is usable day to day: you do not have to export a photo to look at it.

Random access
Any byte range can be decrypted by verifying only the chunks it touches. That is what makes deep zoom into a huge photo, and seeking in a video, possible without decrypting the whole file.
Photos
Any size, correct EXIF orientation, pinch zoom, and region decoding so a 50 MP image does not have to be held whole.
Video & audio
Streamed straight from the encrypted file by the player, through the vault's own reader.
PDF & text
PDFs page through in the app. Text opens inline, showing the first 1 MB - use Open with for the whole of a very large file.
Nothing written to disk
Viewing never produces a plaintext file. Screenshots and screen recording are blocked on every screen.
The exception
Open with and Share must hand another app a real file. Secure Vault warns first, in plain words, then writes a temporary copy that is wiped on lock, on leaving the viewer and at the next cold start.
No preview yet
File types with no in-app viewer say so and offer Open with, rather than showing a blank screen.

Folders, search & sort

Housekeeping
Folders
One level. Move files in and out with multi-select; folder names are encrypted like file names.
Multi-select
Long-press to select, then move to a folder, export the selection, or delete.
Search & sort
Search by file name, sort the grid. Both work on the decrypted names, in memory, while the vault is open.
Deleting
Deletes the encrypted copy permanently and says so before it does. There is no recycle bin - a vault with a bin is a vault with a second copy.

Getting files out

No lock-in

A vault you cannot get out of is a trap. Export is free forever, including after the trial ends.

Export all
Choose a folder and Secure Vault decrypts everything into it. It warns first that the exported copies are unencrypted and readable by anyone with access to that folder; your vault keeps its own encrypted copies.
Export a selection
Same thing for the files you have selected, or a single file from the viewer with Save a copy to this phone.
If it is interrupted
Locking the vault stops an export and reports how many files made it out.
Always free
Viewing and exporting your own files never require a purchase. Only adding new files does.

Backup & restore

Do this first
One file
Back up vault writes a single encrypted file with everything in it, to wherever you choose - Google Drive, an SD card, a computer. The app does the writing through Android's file picker; it has no network access of its own.
Its own password
Locked with a separate backup password, hardened with Argon2id. Your passcode is not used, so a backup can be restored onto a phone that never knew it.
Forget it and it is gone
The app says this before you set it: if you forget the backup password, the backup can never be opened, by you or by anyone else. Write it down somewhere safe.
Restore
Reads the file back into a fresh vault. Settings shows the date of the last backup, and says outright when there has never been one: "Never backed up. Your files exist only on this phone."
No automatic backup
Android's own account-linked backup is switched off for this app, deliberately. Your vault is never copied to a Google account behind your back; the backup file you make is the only one that exists.

Locking & lockout

Access
Auto-lock
The vault locks as soon as the app leaves the foreground, and the key is zeroed out of memory. Coming back means unlocking again.
The picker carve-out
Opening Android's file picker technically backgrounds the app. Secure Vault allows that one case - only within 10 seconds of launching the picker - and locks by itself after 2 minutes away regardless.
Lockout
Three wrong passcodes lock the vault out for a configurable time, 15 minutes by default. Change-passcode attempts count too; a successful fingerprint unlock resets the counter.
Clock tracking
The countdown is tracked on both the wall clock and the phone's uptime with a boot marker. A known limitation: a reboot combined with a clock change can shorten it.
Changing the passcode
Requires the current one - or, if biometric unlock is on, a fingerprint whose released key matches the vault's.
Typed safely
The passcode goes into a wipeable character array through the app's own keypad, never through the system keyboard.

Failed attempts & the intruder photo

Opt-in
The log
Wrong passcodes are recorded with the digits typed and the time. Reports summarises them: how many in the last 7 days, and the most recent.
The photo
With the Settings toggle on, the front camera takes one silent photograph on the second wrong passcode. Camera permission is asked for at that moment, never at startup.
Sealed while locked
Entries are written with a public key and can only be opened with the private half, which exists only inside an unlocked vault. So the log can be written by a stranger and read only by you.
Recent unlocks
Reports also lists your own successful unlocks and how each one was done - passcode or biometric - so an unfamiliar entry is something you can actually notice.

Erasing the vault

Deliberate
The only way data is destroyed
Nothing else in the app can destroy vault contents. Not a failed update, not a reinstall path, not a support action - only this.
24 hours' delay
"Erase vault" schedules a permanent wipe a day out. Any successful unlock cancels it. Someone holding your phone cannot wipe it and walk away; you get a day to come back and stop it.
"Forgot passcode"
Offers exactly this, and nothing else, because there is no other truthful answer.
Manage space
Android's "Clear storage" button opens Secure Vault's own screen instead of silently deleting everything, so the OS cannot erase your vault with one stray tap.

What it protects against

Honest

Every vault app has a boundary. Here is where this one's is, stated rather than implied.

Protects against

  • Other apps on the phone reading your files
  • Cloud backup and device-to-device transfer carrying them off
  • Screenshots and screen recording
  • Off-device brute force - the outer key never leaves the phone
  • Code running as the app while the phone is locked (Android 15+)
  • Anyone reading the attempt log or file names without the passcode

Does not protect against

  • Root access on an unlocked phone - it can use the Keystore key and grind a 6-digit PIN offline despite Argon2id
  • A key already in memory while the vault is open
  • File sizes, dates and types, which stay readable as metadata
  • A file you have exported or shared out - once it leaves, it is an ordinary file
i

No internet permission at all. Not "unused" or "restricted" - the app does not hold it, and a build check fails if any dependency tries to add it. The purchase goes through Google Play's own process, not through the app.

Free trial & the full version

Unlock
3-day trial
The whole app, with a 2 GB limit per file.
5-day grace
Then five more days where you can still view, export and delete. Only adding new files stops. Nobody is locked out of their own photographs the morning a trial expires.
One-time purchase
₹201 through Google Play, once. No subscription. The per-file limit rises to 10 GB.
Export stays free
Always, at every stage, purchased or not. You can take your files and go.
Restore purchase
Same Google account, one tap. The entitlement is cached on the phone so a paying user is never blocked.
Clock changes
Winding the clock back never extends the trial, and licence state lives in its own store so erasing the vault cannot restart it.

Settings reference

Quick lookup
GroupSettingWhat it does
SecurityChange passcodeNeeds the current one, or a matching fingerprint. Turns biometric unlock off afterwards so you re-confirm it deliberately
SecurityBiometric unlockFingerprint or face as a second way in; invalidated if fingerprints are re-enrolled
SecurityCapture photo on 2nd failed attemptSilent front-camera photo. Needs camera permission, asked for only here
SecurityWrong-passcode lockoutHow long the vault stays locked out after three failed attempts
SecurityFailed attemptsThe log: typed digits, times, photos
DataBack up vaultOne encrypted file, its own password, saved wherever you choose
DataRestoreReads a backup file into a fresh vault
DataReportsSecurity check-up, wrong passcodes, recent unlocks, storage by type, largest files
AppearanceOctopus companionReacts when you add, lock, export or back up files. Tap it to dismiss
AppearanceAnimationsFull, Reduced or Off. Your phone's "remove animations" setting always wins
AppearanceTheme / keypad vibrationFollow system, Light or Dark; haptics on the keypad
DangerErase vaultSchedules a permanent wipe of everything, 24 hours out, cancelled by any unlock

Frequently asked

Expectations

What happens if I forget my passcode?

The files cannot be recovered - not by you, and not by us. The passcode is not stored anywhere; it is what unwraps the key, and no copy of that key exists elsewhere. "Forgot passcode" offers only to erase the vault, and that erase waits 24 hours and is cancelled by any successful unlock. This is the cost of a vault only you can open, and the app tells you so before you fill it.

Does Secure Vault upload my files anywhere?

It cannot. The app does not hold Android's internet permission at all, and a build check fails if a dependency tries to add one. No account, no server, no sync, no telemetry.

What happens to the original photos when I add them?

An encrypted copy goes into the vault, then Secure Vault offers to delete the originals so only the locked copy remains. It cannot reach copies already in Google Photos or another cloud backup - remove those in that app too, or the "private" photo is still sitting in someone's cloud.

Can I get my files back if I lose the phone?

Only from a backup you made yourself. Without one, the files exist on that phone and nowhere else - by design. Make the backup early.

Does viewing a file decrypt it to storage?

No. Photos, video, audio, PDFs and text are decrypted in memory, chunk by chunk, as they are read. The only exception is when you explicitly choose Open with or Share, which is confirmed with a warning and wiped when the vault locks.

What happens when the free trial ends?

After 3 days you get a 5-day grace period where viewing, exporting and deleting all still work - only adding new files stops. After that the vault sits behind a one-time ₹201 purchase, and exporting your own files stays free regardless.

Is a 6-digit passcode enough?

Against anyone holding your phone, yes - attempts are rate-limited and locked out, and the key cannot be taken off the device. Against root access on an unlocked phone, a six-digit space is small even with Argon2id. A longer passcode option is on the list.

How big can the vault get?

Up to 10 GB, with a per-file limit of 2 GB during the trial and 10 GB once purchased.

What's new

Release notes
v1.0
First release. Chunked AES-256-GCM storage, the Argon2id key hierarchy with a hardware-backed outer key, in-app viewing with nothing written to disk, encrypted file and folder names, folders, search and multi-select, bulk export, the encrypted backup file, the sealed attempt log with an opt-in intruder photo, the 24-hour delayed erase, security and storage reports, and the octopus companion.
Known limitations
File sizes, dates and types are plaintext metadata. A reboot plus a clock change can shorten a lockout. A longer or alphanumeric passcode option is still open.
Status
Built and unit-tested; not yet published. Ask us to tell you when it reaches Google Play.