Secret Calculator Vault

Overview

Secret Calculator Vault looks and works like an ordinary calculator, but entering your secret PIN opens a private vault for photos.

What It Does

• Working calculator as the disguise
• Secret PIN (4 or more digits), set once and entered in the calculator to open the vault
• Add photos to the vault from the gallery
• View and delete vault items in a built-in viewer
• Vault stays hidden from the normal gallery

How It's Built

• PIN protection: the PIN is never stored as plain text. Only a SHA-256 hash is saved, and entries are checked against it.
• Private storage: vault files are copied into the app's private storage, which other apps and the gallery cannot read.
• Room keeps track of vault items, and Glide loads previews.

Tech Stack

Kotlin, Room, Glide, SHA-256 PIN hashing, Android private app storage.

Status

Complete and installable as an Android app. Not yet published on Google Play.