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Privacy Policy — MosaCrypt

Last updated: October 4, 2026

1. Scope

This Privacy Policy explains how ByteGlo OÜ (“ByteGlo”, “we”, “us”, or “our”) handles information in connection with the iOS application MosaCrypt (the “App”). It applies to the App only. Apple’s policies and the separate privacy policy for byteglo.com also apply where relevant.

2. Controller and contact

  • Company: ByteGlo OÜ
  • Registry code: 17584494
  • Country: Estonia
  • Email:

3. Privacy summary

  • Photo encryption, password-based key derivation, and decryption run on your device.
  • ByteGlo does not receive, upload, host, or store your photos, encrypted PNG files, passwords, or encryption keys.
  • The App has no ByteGlo account, advertising SDK, third-party analytics SDK, or cross-app tracking.
  • Local App data stays on your device unless you choose to share or export it.
  • Premium purchases are processed by Apple through StoreKit.

4. Information ByteGlo does not collect through the App

We do not collect through the App:

  • your original or sealed photos;
  • passwords or derived encryption keys;
  • a contact list or user account;
  • precise location;
  • advertising identifiers;
  • behavioral advertising or third-party analytics event streams;
  • payment-card numbers.

5. Information processed on your device

5.1 Photos and camera

When you grant permission, MosaCrypt can read the photos you allow it to access, add sealed or restored images to Photos, and use the camera to capture a new photo. The App processes image pixels locally. Photo Library and Camera access can be changed in iOS Settings.

5.2 Passwords and encryption

Your password is used locally to derive a 256-bit key using PBKDF2-HMAC-SHA256 with a random salt. The photo is encrypted and authenticated using AES-256-GCM through Apple CryptoKit. The password is not sent to ByteGlo and is not stored for password recovery. A forgotten password cannot be recovered by ByteGlo.

5.3 Sealed PNG files and local library

The encrypted payload is packed into lossless PNG pixels. The App may save a copy in its private Sealed Library and may store supporting encrypted-container data in the App’s local Application Support directory. These files remain on the device unless you share, export, replace, or delete them.

5.4 Local preferences and Keychain records

The App stores settings such as appearance, language, onboarding status, resolution, and watermark choices locally. A non-secret usage counter and status marker may be stored in Apple Keychain to enforce the free-use allowance and show local status. These records do not contain your photos, passwords, or encryption keys. Keychain records may persist after reinstall depending on iOS behavior.

5.5 Photo replacement

If you choose a replace action, the App uses Apple Photos APIs to add the sealed or restored result and remove the selected library item. The removed item may remain in the Photos “Recently Deleted” album for a period controlled by Apple, and iCloud Photos or other backups may retain copies under your Apple settings.

5.6 Purchases

Premium is a one-time In-App Purchase processed by Apple through StoreKit. Apple handles billing, transaction history, refunds, and payment credentials. ByteGlo does not receive your complete payment-card details. The App reads Apple’s verified entitlement so it can unlock Premium features.

6. Sharing and third-party destinations

MosaCrypt shares a file only when you initiate sharing or export. After you send a sealed or restored image to another app, person, cloud drive, messaging service, or storage provider, that destination’s terms and privacy practices apply. Some services modify or recompress images; this can damage the encrypted pixels and make a MosaCrypt PNG impossible to reveal.

7. Analytics, advertising, and tracking

The App does not include third-party advertising, tracking, or analytics SDKs, and ByteGlo does not use the App to track you across other companies’ apps or websites. Apple may process App Store analytics, purchases, and diagnostics under Apple’s policies. If you opt to share diagnostics with developers through Apple, ByteGlo may receive reports provided by Apple and use them to investigate reliability issues.

8. Support communications

If you contact us, we process your email address, message, and any attachments you choose to send so we can answer your request. Do not send passwords or unencrypted private photos in a support message.

9. Purposes and legal bases

Where GDPR or similar law applies, ByteGlo may rely on:

  • contract to provide requested App and support functionality;
  • consent where you grant optional device permissions or send information voluntarily;
  • legitimate interests to answer support messages and investigate optional diagnostics, balanced against your rights;
  • legal obligation where retention or disclosure is required by law.

10. Disclosure and international transfers

We do not sell or rent personal information from the App. We may disclose support information when required by law or to service providers used to operate email and website hosting. Because the App does not upload your photo content to ByteGlo, it does not transfer that content to our servers in another country.

11. Retention and deletion

  • Photos and exported MosaCrypt PNG files remain wherever you save them until you delete them.
  • Sealed Library files and local preferences remain until you delete them in the App, clear App data, or uninstall the App, subject to iOS behavior.
  • Keychain status and free-use records may remain after uninstall or reinstall until removed by the operating system or a device reset.
  • Support communications are retained only as long as reasonably needed to resolve the request, maintain business records, or comply with law.

12. Security and your responsibilities

MosaCrypt is designed to keep photo encryption local and uses standard authenticated encryption. No software or storage method can guarantee absolute security. You are responsible for keeping your password, device, Apple ID, exported files, and backups secure. Keep an unmodified lossless copy of each sealed PNG you need.

13. Children

The App is not directed to children under 13, and ByteGlo does not knowingly collect their personal information through the App. If you believe a child sent us personal information through support email, contact us so we can take appropriate action.

14. Your rights

Depending on your location, you may have rights to access, correct, erase, restrict, port, or object to processing of personal data held by ByteGlo, and to withdraw consent. Most App content is controlled directly on your device and is not available to ByteGlo. For information you sent us through support, contact us using the email above. You may also complain to a competent supervisory authority, including the Estonian Data Protection Inspectorate.

15. Changes

We may update this Policy to reflect changes to MosaCrypt, law, or our practices. We will update the date above and publish the revised version on this page.