No trust required
No server that would have to promise anything. Your data sits as one file on your device.
Security beta, not externally audited
Your seed phrase
never leaves
this device.
MASTRPass is a local vault for BIP39 seed phrases, credentials and secure notes. No account, no backend, no telemetry. The Android app does not even hold permission to reach the internet.
Container format MASTRP01
Little-endian
0x00Magic8 B
0x08Version2 B
0x0CArgon2id12 B
0x18Vault ID16 B
0x28Salt16 B
0x38HKDF-Mix32 B
0x58Nonce24 B
0x70DEK wrapper48 B
0xC0Payload, authenticated and paddedvariable
Seed phrases are encrypted a second time inside the payload, with one key per entry. Padding to fixed size classes hides how much the vault holds.
Why MASTRPass exists
The seed is rarely the problem. Everything around it is.
Most losses do not happen because someone loses the 24 words. They happen because the derivation path is missing, the passphrase is forgotten, nobody remembers which backup belongs to which wallet, or because the paper holds a typo that only surfaces on recovery day.
MASTRPass keeps exactly those things in one place, encrypted, offline and built so you can check how it works.
01
02
Two real factors
Manual unlocking needs the master password and the full recovery key. The two are kept separate.
03
Documented
Format, key derivation and threat model are written down, not hinted at.
04
Open source core
The Rust crypto core is licensed AGPL-3.0-only. No black box crypto module.
How it is protected
Cryptography you can look up
No home made schemes, no secrets in the design. Established building blocks, put together cleanly and documented with clear limits.
| Key derivation | Argon2id, Android 128 MiB, t=4, p=2. Windows 512 MiB, t=4, p=2 |
| Vault encryption | XChaCha20-Poly1305, authenticated |
| Companion store | AES-256-GCM, a separate key per file and purpose |
| Key mixing | HKDF-SHA-256 from password and recovery key |
| Seed phrases | second encryption layer, one key per entry |
| Metadata | padded to size classes, length reveals nothing |
| Tampering | the header is associated data, any change is detected |
| Error path | a wrong password and a tampered file look identical from outside |
Mode A
Quick
Biometrics release a key protected by the Android Keystore or by Windows Hello. Fast day to day, bound to the device. The recovery key stays responsible for emergencies.
Mode B
Strict
Master password, full recovery key, then strong biometrics as a device bound confirmation. For vaults you open rarely.
Deliberately absent
No TOTP as a vault factor
Without a backend a TOTP secret would sit on the same device as the vault. That is not a second factor, it is theatre. So it is not here.
Deliberately absent
No automatic wipe
Failed attempts only cause delays, never deletion. A wipe feature ends up locking out the owner more often than it stops an attacker.
Network
No connection possible
Android without the INTERNET permission and without a WebView. The Windows MSIX runs in an AppContainer and declares neither network nor full trust capability.
Images
No storage access
Screenshots arrive only through the system photo picker. No camera permission, no storage permission.
Clipboard
30 seconds
Copied values are marked sensitive and removed after 30 seconds on a best effort basis.
What is inside
Built for daily use, not just for safety
Wallets
Phrase, image or both
Seed phrase as text, as an imported screenshot or combined. With a clear reminder to delete the original outside the app afterwards.
Chains
40 chain profiles
Prepared profiles for the most common networks, sortable and filterable.
Credentials
Logins and notes
Ordinary logins and secure notes are stored apart from the seed area, each encrypted on its own.
Generator
Create passwords
Built in generator, no detour through a website.
Recovery
14 numbered fields
The recovery key is shown, confirmed and entered in clearly numbered blocks. With a checksum against typos.
Transport
Import and export
Encrypted full export as MASTRB02. Older MASTRP01 files are still read.
Languages
7 interface languages
German, English, Spanish, Italian, French, Portuguese, Chinese.
Display
Excluded from capture
The app window is excluded from supported screen recordings, and revealed secrets are hidden again after a short time.
Platforms
Android and Windows
Separate native apps, one shared Rust crypto core, a binary compatible vault format.
Screenshot 1
assets/img/shot-1.png
assets/img/shot-1.png
Screenshot 2
assets/img/shot-2.png
assets/img/shot-2.png
Screenshot 3
assets/img/shot-3.png
assets/img/shot-3.png
The honest part
What MASTRPass cannot do
Security software that only shows its strengths sells you a feeling instead of a tool. All of this is written down in the threat model in the repository.
Until an independent audit exists, MASTRPass must not be your only backup and must not secure high value wallets on its own. Metal and paper stay the foundation. MASTRPass is the order around them.
No protection against
- an already compromised, rooted or unlocked operating system
- tampered keyboards, accessibility services or recording outside the app
- coercion, social engineering and a compromised paper backup
- losing password and recovery key at the same time
- bugs in the platform, in crypto libraries or in this unaudited version
- access to memory during an already unlocked session
- copies of imported images still sitting in gallery, cloud or trash
- clipboard managers that record copied values outside the app
Download
Verify first, install second
All files are served directly from mastrpass.xyz. Compare the checksum before you run anything. The instructions are right below.
APK SHA-256
332a146bd8e05b6691d10a395b521b726d0d594f5f5f628d5e3082039a2b9de2
Source SHA-256
916e4e1e44e23a671c2ddc57cf7610a44ae7ef19abdb0519695b868500079443
Signing certificate
bfc972850a1136adea8ad3199e55d3219f3fdef292e61930b0f945ee7a535cf3
Moving from an earlier beta: the one time beta signing key was destroyed. Export encrypted first. Depending on the installed signature you may need to uninstall beforehand.
Portable SHA-256
PUT SHA-256 OF THE PORTABLE ZIP HERE
MSIX SHA-256
PUT SHA-256 OF THE MSIX HERE
Source SHA-256
PUT SHA-256 OF THE SOURCE ZIP HERE
The MSIX build runs in an AppContainer without a declared network capability. The portable build does not have that extra boundary. Until an owner certificate exists the package is unsigned and Windows will show a warning.
All checksums in one file: SHA256SUMS.txt. iOS is not available yet.
Verification
Verified in 30 seconds
A checksum proves the file you downloaded is exactly the one published here. If a single character differs, do not install it.
Windows, PowerShell
Get-FileHash .\MASTRPass-0.4.0-security-beta.apk -Algorithm SHA256
Linux or macOS
shasum -a 256 MASTRPass-0.4.0-security-beta.apk
Also check the Android signature
apksigner verify --print-certs MASTRPass-0.4.0-security-beta.apk
Rule 1
This domain only
Never download from a mirror, a Telegram channel or a link in a direct message. Type mastrpass.xyz yourself.
Rule 2
Nobody asks for your seed
There is no support desk, no recovery service and no reason to show your words to anyone. Not to us either.
Rule 3
Store the recovery key separately
Master password and recovery key are two factors. Kept in one place they are one.
Source and status
Open, versioned, unfinished
The Rust crypto core is licensed AGPL-3.0-only. Every version is archived with a signed file, a source archive, checksums and release notes.
Before a stable release come an independent audit of the core and the platform boundaries, a reproducible build pipeline with an owner controlled signing key, device testing, a review of the companion store, reviewed translations and a full accessibility pass.
| Android | 0.4.0-security-beta, versionCode 6 |
| Windows | 0.1.1-security-alpha, x64 |
| Crypto core | Rust, AGPL-3.0-only |
| Android stack | Kotlin, Jetpack Compose |
| Windows stack | .NET 10, WinUI 3, Windows Hello |
| Formats | MASTRP01, MPXENC01, MASTRB02, MPWHLO01 |
| Operation | offline, without backend, telemetry or WebView |
| Status | not externally audited |
Support
MASTRPass runs on donations
There is no subscription, no account, no advertising and no data that could be sold. Audit, signing certificates and further development depend on voluntary contributions.
PUT DONATION ADDRESS HERE
Always check the address in full, character by character. We publish it here and nowhere else.
Report a vulnerability
Found something? Please tell us.
Contact via askmastr.xyz or x.com/MASTRlabs. Until a dedicated private security channel is published, please send reproducible technical details only and agree on disclosure beforehand.
Never put in a report
- Seed phrases
- Recovery keys
- Vault files
- Keystores or signing passwords
A project by
