Vault Calculator: Secret Notes

Vault Calculator — Not everyone's calculator is just a calculator.  A CALCULATOR WITH A SECRET Vault Calculator looks and works like a normal calculator. But behind the keypad is a secure, encrypted vault for your private notes — protected by your personal code. No one would suspect that your calculator holds your PINs, passwords, and confidential notes.  TRIPLE-LAYER ENCRYPTION Your notes are protected by three independent layers of security: • AES-256-GCM encrypts every single note individually — the encryption standard used by banks and governments worldwide. • Argon2id protects your access code, stored in your phone's hardware security module (Android Keystore). Even a supercomputer would need years to crack it. • SQLCipher encrypts the entire database — so even if someone extracts the database file, the content remains unreadable. Without your code, nothing works. Your code is never stored, never transmitted, never seen by anyone — not even us.  SELF-DESTRUCT Enter your code backwards and all notes are instantly and permanently deleted. One second, everything gone. The code stays — you can start fresh.  100% OFFLINE — NO CLOUD, NO ACCOUNT, NO TRACKING Vault Calculator works entirely offline. No cloud sync. No account required. No analytics. No tracking. Your data never leaves your device. Screenshots are blocked (FLAG_SECURE) — no one can photograph your screen.  EXPORT & IMPORT Switching phones? Export your notes as an encrypted .vault file and import them on your new device with your code. Your notes stay yours — encrypted with AES-256, fully offline.  FULLY FUNCTIONAL CALCULATOR Vault Calculator is a real calculator — not a fake screen. It handles everyday math and includes a scientific mode with sin, cos, tan, logarithms, square roots, π, and more. Use it normally, no one will notice.  WHO IS VAULT CALCULATOR FOR? • People who want to store PINs, passwords, and access codes securely • Anyone who needs a private, offline notes app hidden from prying eyes • Users who want real encryption — not just a hidden folder • People who value privacy: no cloud, no account, no tracking • Anyone who wants their notes to look like nothing more than a calculator  FEATURES AT A GLANCE • Disguised as a fully working calculator • Triple-layer encryption (AES-256-GCM + Argon2id + SQLCipher) • Self-destruct: code backwards = everything wiped • 100% offline — no cloud, no account, no tracking • Screenshot protection (FLAG_SECURE) • Export & Import encrypted .vault files • Scientific calculator mode • Code strength indicator with brute-force time estimate • Android Keystore hardware protection • No internet permission required • Available in German and English  SECURITY DETAILS Vault Calculator uses Envelope Encryption architecture: • A 256-bit random Master Key (MK) is generated on first setup • The MK is wrapped with your code using Argon2id and stored in the Android Keystore • The MK encrypts the SQLCipher database • Each note is additionally encrypted with AES-256-GCM using HKDF-derived field keys • Your code is never stored — only the encrypted wrapper This means: changing your code takes milliseconds (only the wrapper is re-encrypted), your notes stay encrypted, and the Master Key is 256-bit random — not guessable.  NO ADS IN THE VAULT The calculator is your space. The vault is your space. No one should see your private notes — and no one should fill your private space with ads. --- Vault Calculator — by exvode Made in Germany 🇩🇪 Privacy is not a feature. It's the foundation.