Android App · Stealth Vault

It's a
Calculator.
Or is it?

CalculatorLKR hides a military-grade file vault behind a perfectly functional calculator. No one will ever know what's on your phone.

256-bit
Encryption
0
Obvious branding
100%
Free & open
Vault Unlocked
1234 =
✓ Vault
AC
+/-
C
÷
7
8
9
×
4
5
6
1
2
3
+
0
.
=
🔒 AES-256 Encrypted

Everything you need.
Nothing to see here.

Built for people who value privacy. Designed to be invisible. Engineered to be unbreakable.

🎭
Stealth Calculator UI

Opens to a fully working calculator. No vault branding, no suspicious icons. It just looks like a calculator app — because it is.

🔐
Strong Encryption

Files are encrypted directly into the app's private storage. Unreadable outside the app — even if someone copies your device.

👆
Biometric Unlock

Use fingerprint or face unlock on supported devices. Your files open as fast as your calculator — and just as naturally.

Auto-Lock Safety

Automatically locks when the app moves to background. Optional idle timeout ensures the vault is never left open by accident.

📂
SAF File Access

Uses Android's Storage Access Framework for safe file picking and exporting. Zero file access without your explicit approval.

🛟
PIN Recovery

Forgot your PIN? Long-press C on the calculator screen to trigger a secure recovery flow via your secret question.

How it works

Five steps. Completely covert.

01
Open the "Calculator"

Install and open the app. You see a normal, functional calculator. Nothing suspicious — tap some numbers, it all works.

02
Unlock the Vault

Type your secret PIN as if entering a calculation (e.g. 1234), then press =. The vault unlocks silently.

03
Lock Files (Encrypt)

Choose "Lock Files" from the hidden menu. Pick files via the Android picker. They get encrypted into secure private storage.

04
Unlock Files (Decrypt + Export)

Open the vault, pick the file to restore, and export it to any folder you choose using SAF — safe and private.

05
Recover Your PIN

Long-press C on the calculator screen to access the PIN recovery screen. Answer your security question to reset.

CalculatorLKR · vault.log
App launched...
Displaying calculator UI
User input: 1 2 3 4 =
Checking PIN...
✓ PIN matched. Vault open.
 
Selecting: report_q3.pdf
Encrypting file...
✓ Locked into private storage
 
App backgrounded
Auto-lock triggered
✓ Vault sealed.
 
_
Security

Encrypted. Sealed. Private.

// Encryption details
algorithm AES-256-GCM
key_size 256 bits
storage app private dir
access auth required
file_state LOCKED · unreadable
after_auth decrypted + exported
saf_api ✓ android standard
🔒
Private Storage Isolation

Encrypted files live in the app's private directory — inaccessible to other apps and invisible to file browsers, even without root.

🕵️
No Vault Branding

The app icon, launcher name, and UI are purely calculator-themed. No telltale signs for anyone scrolling through your phone.

📡
Storage Access Framework

Uses Android's official SAF — no broad storage permissions needed. Files are picked and exported only when you choose, each time.

Idle Timeout & Auto-Lock

Walk away and the vault locks itself. Configurable idle timeout ensures no one can access your files if you leave your phone unattended.

Download

Get CalculatorLKR

Free. No ads. No tracking. Just a calculator — and your privacy.

📦
CalculatorLKR.apk
Android 11.0+ · ARM64 / ARMv7 · Sideload required
1
Download the APK file to your Android device
2
Go to Settings → Security → Install unknown apps and allow your browser
3
Open the downloaded APK and tap Install
4
Launch the app, set your PIN, and start locking files
Download APK — Free
🛡 CalculatorLKR uses the Android Storage Access Framework and stores all encrypted files in the app's private directory. No broad storage permissions are requested. Files are never uploaded or shared externally.