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What is VaultZero?

VaultZero is a local-first Android vault for passwords, 2FA codes, payment cards, API keys, crypto wallets/seed phrases, secure notes and identity documents. It is built with Kotlin and Jetpack Compose and is deliberately incapable of connecting to the internet: the app declares no INTERNET permission and contains no networking code.

Everything is encrypted on the device with a random 256-bit vault key, wrapped by your master password and a 12-word recovery phrase. Backups are encrypted files written through Android's system file picker — there is no account, cloud sync, analytics or remote service.

Status: production release v1.3.1 (versionCode 5). Self-tested and pentested; an independent audit is still recommended before relying on it for high-risk secrets.

Table of contents

• Screenshots
• Features
• Security at a glance
• Download & install
• Build from source
• Testing
• Architecture
• Repository map
• Documentation
• Privacy
• Contributing
• License

Screenshots

Vault (dark)	Light theme	2FA dashboard
Settings	Generator	Audit

More in docs/SCREENSHOTS.md.

Features

Vault

• Six record types: Logins, Payment cards, API secrets, Crypto wallets, Secure notes, Identities.
• AES-256-GCM per-record encryption with AAD binding; titles, categories and tags are encrypted too — SQLite only stores [ENCRYPTED] placeholders.
• Live RFC 6238 TOTP codes (30 s) inline in the list and in a dedicated 2FA dashboard.
• Search operators: type:login, tag:work, is:fav, and audit-backed filters is:weak, is:reused, is:stale, is:no2fa, is:clean.
• Sort by favourites, title, recently updated or recently used; optional grouping by type; multi-select bulk delete/favourite; undo delete.
• Copy actions are sensitive-clipboard aware; revealed secrets re-mask after 15 seconds.

Security

• Random 256-bit vault master key (VMK); per-record AES-256-GCM with VaultZero_Record_v2:<id>:<type> AAD.
• PBKDF2-HMAC-SHA256 with 600,000 iterations and 128-bit salts; transparent upgrade of legacy vaults on unlock.
• BIP-39 128-bit recovery kit (2048-word standard, unique words); change master password without re-encrypting records; rotate an exposed kit without changing the vault.
• Hardware-backed biometric unlock through Android Keystore + BiometricPrompt.CryptoObject — per-use authentication, invalidated when biometrics are re-enrolled. The prompt auto-appears on app open when enabled.
• Configurable auto-lock, background lock (screen-off locks immediately; SAF picker exempt), clipboard auto-clear, FLAG_SECURE, Recent-Apps preview blocked.
• Local security audit (weak/reused/stale/2FA), offline by construction.

Backups

• First-run migration: a new phone can restore a full backup with the existing 12-word recovery phrase — no new seed phrase — keeping the original master password (or setting a new one).
• Versioned encrypted envelope via Android's Storage Access Framework only.
• Restore with the source master password or 12-word recovery phrase; optional phrase-only export (password envelope stripped).
• Verified imports before any write: duplicate-safe merges, in-place updates, atomic Room transaction, explicit salvage of readable records from a damaged file.
• Timestamped filenames; import/export progress feedback.

Design & ergonomics

• One UI-inspired design: true-black/#FAFAFA grounds, single accent blue, squircle containers, floating pill navigation, large collapsing title.
• Light / dark / system appearance; launcher shortcuts (New login, Generator); passphrase separator/capitalisation options.

Security at a glance

Area	Implementation
Records	AES-256-GCM, random per-record IV, 128-bit tag, AAD bound to record id + type
Key hierarchy	Random 256-bit VMK wraps records; VMK wrapped by password KEK and recovery-phrase KEK
Password KDF	PBKDF2-HMAC-SHA256, 600,000 iterations, 128-bit random salt
Recovery	BIP-39 12-word phrase (128-bit entropy) with unique words; legacy v1.x phrases still accepted; encrypted under the VMK at rest; rotatable in Settings
Biometrics	AES-256-GCM Keystore key, AUTH_BIOMETRIC_STRONG, per-use auth (CryptoObject), StrongBox→TEE, invalidated by biometric enrolment changes
Backups	AES-256-GCM envelope, redacted metadata, 8 MiB import cap, phrase/password restore
Network	No INTERNET/ACCESS_NETWORK_STATE permission, no networking libraries
Screen capture	FLAG_SECURE, recents screenshot disabled on API 33+
At rest	SQLite titles/categories/tags redacted; prefs contain only wrapped keys, salts, verifiers
Offline	No accounts, cloud, analytics, crash reporting, ads or trackers