1. Introduction
LESRA Future Apps (“we”, “us”, “our”) develops and operates the Scientific Calculator mobile application (the “App”). This Privacy Policy explains what information we collect, how we use it, and your rights regarding your data.
This Privacy Policy also serves as our Data Policy and Data Safety Summary for Google Play Store compliance purposes.
By downloading, installing, or using the App, you agree to this Privacy Policy. If you do not agree, please uninstall the App and discontinue use.
2. Data Controller
Developer / Publisher: LESRA Future Apps
App Name: Scientific Calculator
Package Name: com.lesra.scientificcalculator
Developer Email: jdronquillo16@gmail.com
Contact / Privacy Inquiries: jdronquillo46@gmail.com
3. Information We Collect
3.1 Data Stored Locally on Your Device (Never Transmitted to Us)
The following data is stored exclusively on your device and is never uploaded to our servers:
| Data | Purpose | Storage |
|---|---|---|
| Calculation history (last 20 entries) | Display recent calculations | SharedPreferences (local) |
| Pinned calculations | User-bookmarked results | SharedPreferences (local) |
| 6-digit vault PIN (SHA-256 hash only) | Authenticate vault access | flutter_secure_storage (Android Keystore) |
| Decoy PIN hash (optional) | Secondary security layer | flutter_secure_storage (Android Keystore) |
| Biometric unlock preference | Enable/disable fingerprint/face unlock | flutter_secure_storage (local) |
| Auto-lock timeout setting | Auto-lock vault after inactivity | SharedPreferences (local) |
| Private vault photos | Hidden photo storage | App private directory (not accessible by gallery) |
| Private vault videos | Hidden video storage | App private directory (not accessible by gallery) |
| Private vault notes | Private text notes | App private directory (local) |
| Google account name, email, photo URL (if signed in) | Display account info; subscription management | SharedPreferences (local) |
| Subscription status | Determine ad-free access | SharedPreferences + Google Play (verified by Play) |
| App theme and UI preferences | User customization | SharedPreferences (local) |
3.2 Data Collected by Third-Party Services
The App integrates with the following third-party services that may collect data under their own privacy policies. See Section 5 for full details.
- Google AdMob — may collect advertising identifier and device info to serve ads
- Firebase Analytics — collects anonymous usage events (see Section 5.3)
- Google Sign-In — accesses name, email, and profile photo if you choose to sign in
- Google Play Billing — processes subscription payments (we receive no payment details)
3.3 Data We Do NOT Collect
- ❌ Your vault files (photos, videos, notes) — stored on-device only, never uploaded
- ❌ Your actual vault PIN — only a one-way SHA-256 hash is stored locally
- ❌ Biometric data (fingerprint, face) — handled entirely by the Android OS
- ❌ Location or GPS data
- ❌ Contacts, SMS, or call logs
- ❌ Device microphone or call recording
- ❌ Health or financial data
4. How We Use Your Data
- Calculator functionality: History and pinned results stored locally for display
- Vault authentication: Hashed PIN verified locally — no server call required
- Subscription enforcement: Subscription status checked via Google Play to disable ads
- Analytics: Anonymous event data used to understand feature usage and improve the App
- Ads: AdMob serves ads to non-subscribed users based on advertising preferences
5. Third-Party Services
5.1 Google AdMob
We display banner, interstitial, and rewarded video advertisements through Google AdMob. AdMob may collect your device’s advertising identifier (GAID) and other device signals to deliver targeted ads.
Ads are not shown to subscribed users.
To opt out of personalized ads: Google Settings → Ads → Opt out of Ads Personalization
AdMob Privacy Policy: https://policies.google.com/technologies/ads
5.2 Google Play Billing
Subscription payments ($2.00/month) are processed entirely by Google Play. We do not
receive, store, or process any payment card or financial information. All billing is
governed by Google’s terms.
Google Play Terms: https://play.google.com/about/play-terms/
5.3 Firebase Analytics (Google)
We use Firebase Analytics to track the following anonymous events:
| Event | What It Records | Personal Data? |
|---|---|---|
| app_open | App launched | No |
| locker_open | Private vault accessed | No (no file content) |
| ad_impression | Ad displayed | No |
| subscribe_attempt | Subscribe button tapped | No |
| login | Google Sign-In completed | No (method only) |
All analytics data is aggregated and anonymous. No vault contents, files, or personal
identifiers are included.
Firebase Privacy Policy: https://firebase.google.com/support/privacy
5.4 Google Sign-In
Google Sign-In is optional. If you choose to sign in, we receive your Google account name, email address, and profile photo URL. This information is stored locally on your device only and is used solely to display your account details and associate your Google Play subscription.
We do not upload your Google account data to our servers.
Google Privacy Policy: https://policies.google.com/privacy
6. Private Vault — How Your Files Are Protected
- Storage location:
getApplicationDocumentsDirectory()/locker/— only accessible by this App - Gallery/file manager exclusion: A
.nomediafile is placed in all vault sub-directories, preventing Android’s MediaStore from indexing vault files - PIN security: Your 6-digit PIN is hashed with SHA-256 and stored in Android Keystore via
flutter_secure_storage— the raw PIN is never stored anywhere - Biometrics: Fingerprint and face recognition are processed entirely by the Android BiometricPrompt API — we receive only a pass/fail result, never biometric data
- Decoy PIN: A secondary PIN can show an empty vault — real files remain unaffected
- Auto-lock: Vault automatically locks after a configurable inactivity timeout
7. Data Storage & Retention
7.1 On-Device Data
All data described in Section 3.1 remains on your device for as long as the App is installed. Uninstalling the App will delete all locally stored data, including vault files.
7.2 Firebase Analytics
Anonymous analytics events are retained by Firebase for up to 14 months by default, per Google’s retention policy. No personal data is included in these events.
7.3 Google Sign-In Session
Cached Google account name, email, and photo are stored locally and are deleted when you sign out within the App or uninstall the App.
7.4 Data Deletion
To delete your data:
- Vault files: Open the App → vault → delete files individually, or uninstall the App to delete all vault data
- Google account / analytics data: Email us at jdronquillo46@gmail.com with subject “Data Deletion Request” — we will respond within 30 days
8. Device Permissions
| Permission | Why It Is Used |
|---|---|
| READ_MEDIA_IMAGES / READ_MEDIA_VIDEO | Import photos and videos from device gallery into the private vault |
| READ_EXTERNAL_STORAGE / WRITE_EXTERNAL_STORAGE | Import files on older Android versions (API < 33) |
| CAMERA | Capture a photo directly into the vault from within the App |
| USE_BIOMETRIC / USE_FINGERPRINT | Optional fingerprint or face unlock for the private vault |
| INTERNET | Display ads (AdMob), Firebase Analytics, Google Sign-In, and Play Billing |
The App does not request location, contacts, microphone, or SMS permissions. Storage permissions are used only to import files you select — the App does not scan or upload your device storage.
9. Data Security
- 🔒 Android Keystore encryption — PIN hash stored using hardware-backed key storage
- 🔒 App private directory — vault files inaccessible to other apps or system media scanners
- 🔒 Code obfuscation — App compiled with
--obfuscateand ProGuard to prevent reverse engineering - 🔒 TLS/SSL encryption — all network traffic (AdMob, Firebase, Google Sign-In) is encrypted in transit
10. GDPR Compliance (EU Users)
If you are located in the European Union or European Economic Area, you have the following rights under the General Data Protection Regulation (GDPR):
- Right to Access: Request a summary of any data we hold about you
- Right to Rectification: Request correction of inaccurate personal data
- Right to Erasure: Request deletion of your data (“right to be forgotten”)
- Right to Data Portability: Receive your data in a machine-readable format
- Right to Object: Object to data processing for direct marketing
- Right to Withdraw Consent: Withdraw consent for ad personalization at any time
To exercise any of these rights, contact us at:
jdronquillo46@gmail.com
We will respond within 30 days.
11. Children’s Privacy (COPPA)
The App is rated Teen (13+) on Google Play. The private vault feature is intended for adult personal use.
- We do not knowingly collect personal information from children under the age of 13
- If you are a parent or guardian and believe your child under 13 has used this App, please contact us immediately at jdronquillo46@gmail.com
- We will delete any data associated with a child under 13 promptly upon notification
12. Google Play Data Safety Disclosure
The following summarizes our Data Safety form responses for Google Play:
| Category | Collected? | Shared? | Purpose |
|---|---|---|---|
| Name, Email (Google Sign-In) | Optional | No (local only) | Account display, subscription |
| App interactions / usage data | Yes (anonymous) | Firebase (Google) — anonymized | Analytics, app improvement |
| Advertising ID | By AdMob SDK | Google AdMob | Ad delivery |
| Photos / Videos / Notes | On-device only | Never | Private vault storage |
| Payment info | No (Google Play handles) | No | Subscription processing by Google |
| Location | No | No | N/A |
| Contacts / SMS / Calls | No | No | N/A |
| Biometric data | No (Android OS handles) | No | Vault biometric unlock (OS-level) |
13. Changes to This Policy
We may update this Privacy Policy from time to time. Material changes will be communicated via an in-app notification or an updated “Last Updated” date at the top of this page. Continued use of the App after changes constitutes acceptance of the revised policy.
We encourage you to review this Privacy Policy periodically.
14. Contact Us
For privacy questions, data requests, or concerns, contact us:
LESRA Future Apps
📧 Privacy / Support Email: jdronquillo46@gmail.com
We aim to respond within 3–5 business days.