True File Locker

True File Locker is an encrypted file-security app for Android developed by Kalenux.[1] It locks, encrypts and protects files and folders with AES-256 encryption, biometric unlock and a hidden vault that stores no decrypted data on disk.[1] The app has no cloud backup, no analytics and requests no internet permission, so everything stays on the device.[1]

EncryptionAES-256-GCM[1]

UnlockBiometric + PIN fallback[1]

Key storageAndroid Keystore[1]

Cloud dependencyZero[1]

Internet permissionNone[1]

StatusLive[1]

DEVICE BOUNDARY

YOUR PHONE

🔒Encrypted vaultAES-256-GCM container

🔒Vault keyAndroid Keystore, biometric-bound

🔒Open fileDecrypted in memory only

✕Cloud backup

✕Analytics

✕Network calls

Nothing crosses the boundary: the app requests no internet permission.[1]

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Overview

Files added to the vault are encrypted using AES-256 before being stored, and the original plaintext file is securely deleted from its source location. No decrypted version of a protected file ever sits on the device’s storage: files are only decrypted in memory when the user opens them within the app, and are immediately re-encrypted when the user closes them or exits the vault.[1]

The app supports biometric unlock (fingerprint and face recognition) in addition to PIN authentication, and a hidden vault mode in which it disguises itself as a calculator on the home screen.[1]

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History and motivation

Locking private files on a phone usually means installing an unknown app and hoping for the best. Kalenux describes too many “vault” apps as quietly uploading data to servers the user will never see, hiding a flimsy lock behind a paywall, or requesting permissions that have no business near private files.[1]

“A file locker that phones home is not a file locker: it is a leak waiting to happen.”[1]

Real protection, in Kalenux’s framing, cannot depend on a company’s promise not to look; it has to be built so that there is nothing to look at in the first place.[1]

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Lifecycle of a protected file

01ImportFile added to the vault

02EncryptAES-256-GCM, in memory

03Wipe originalOverwritten with random data, then deleted

04OpenDecrypted in memory only

05CloseRe-encrypted immediately

At no point in this cycle is a plaintext copy written to persistent storage.[1]

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Features

Feature	How it works
AES-256 encryption	Files are encrypted using AES-256-GCM before storage; encryption and decryption happen in memory
Biometric unlock	Fingerprint and face recognition via the Android BiometricPrompt API, falling back to PIN; the vault key is held in the Android Keystore, tied to biometric authentication
Calculator disguise	The app can appear as a working calculator; entering a secret PIN opens the vault
Secure deletion	Imported originals are overwritten with random data before deletion, preventing recovery with standard tools
Encrypted photo vault	Photos and videos stored with thumbnails generated and displayed in memory, never written to a decrypted cache
Encrypted notes	A built-in editor for passwords, PINs and other sensitive text, encrypted with the same key in the same container
No internet permission	The app makes no network calls, so vault contents cannot be exfiltrated over the network by the app itself

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Security model

There is no cloud backup, no sync to external services and no analytics. Because the app requires no internet permission, data protection relies entirely on local encryption and the user’s PIN or biometric: there is no backend system that could be compromised to expose vault contents.[1]

Threat	Mitigation
Server breach	No server exists; nothing leaves the device
Recovery of deleted originals	Originals overwritten with random data before deletion
Decrypted cache on disk	Files and thumbnails decrypted in memory only
Someone looking at the phone	Calculator disguise gives plausible deniability
Stolen PIN	Vault key tied to biometric authentication in the Android Keystore

Mitigations as described on the Kalenux product page.[1]

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Reception

On the Kalenux product page, True File Locker holds an average rating of 4.6 from nine moderated reviews.[3]

Best free file locker on Google Play★★★★★

“Tested several apps before settling on True File Locker. It’s the only free one that offers actual encryption rather than just hiding files behind a PIN. Big difference.”

Patrick Owusu, Accra, Ghana · May 2026

Recommended by my IT department★★★★★

“Our company IT team recommended True File Locker for employees who need to store sensitive files on personal devices. Easy to set up and the access controls are exactly right.”

Florian Bucher, Basel, Switzerland · May 2026

Essential for anyone with sensitive data★★★★★

“I work in finance and need to protect client documents on my phone. True File Locker handles this perfectly. The encryption documentation reassured me that this is done properly.”

Elena Morozova, Moscow, Russia · May 2026

Great for privacy-conscious users★★★★★

“Solid tool with good documentation. Appreciate that the encryption approach is explained transparently rather than hidden behind vague marketing terms.”

Sara Lindqvist, Uppsala, Sweden · May 2026

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References

[1]True File Locker: Project Details & Reviews. Kalenux. kalenux.com.tr/product/true-file-locker
[2]True File Locker on Google Play. play.google.com/store/apps/details?id=com.truefilelocker
[3]True File Locker reviews. Kalenux. kalenux.com.tr/product/true-file-locker/reviews

CITE THIS ARTICLEKalenux. (2026). True File Locker. Kalenux product reference. kalenux.com.tr/product/true-file-locker

Download True File Locker on Google Play→