SMS Tech

A modern, private SMS & MMS app for Android — built with Kotlin, Jetpack Compose and Material 3. No ads, no trackers, no analytics.

Features

- Default SMS / MMS app for Android (KitKat → Android 14+). - Single-Activity Compose UI, Material 3 with dynamic colors + AMOLED true-black. - Encrypted Room database (SQLCipher), AndroidKeyStore-wrapped master key. - App lock: PIN with PBKDF2-HMAC-SHA512, monotonic exponential backoff after failed attempts. - Optional panic-decoy PIN: when entered, the app opens in a session where the vault (a UI-level folder of hidden conversations) is fully invisible — neither its top-bar entry point nor its rows / messages are reachable, even via saved navigation state or share-target deep links. Note: the vault is currently a logical UX boundary inside the (already-encrypted by SQLCipher) Room database, not a separately-keyed cryptographic envelope. A second-layer vault crypto keyed by a setUserAuthenticationRequired = true Keystore alias is planned for v1.1.1 — see SECURITY.md* for the threat model and the explicit limit. - Inline reply & mark-as-read actions on notifications, per-conversation overrides. - Voice SMS — on-device dictation via SpeechRecognizer (no network). - PDF export of any conversation, generated locally via PdfDocument (no external lib). - Scheduled sending via WorkManager (exact alarms when granted). - Backup & restore in .smsbk (AES-256-GCM + PBKDF2) and XML SMS-Backup-Restore compatible. - Migration assistant: reads the system SMS provider once SMS Tech is set as the default app. - Bilingual UI: English & French, switchable at runtime. - F-Droid friendly: no Google libraries, no proprietary blobs.

*SECURITY.md: https://github.com/gitubpatrice/SMS-TECH/blob/main/SECURITY.md

Privacy

No data is collected. No analytics, no crash reporting, no remote logging. The only network calls SMS Tech can make are MMS transport via the carrier's MMSC (INTERNET permission), and only when sending or receiving an MMS.

SMS is not end-to-end encrypted at the protocol level — this is a limitation of the carrier network, not a choice. SMS Tech protects what is stored on the device with SQLCipher and the AndroidKeyStore. For true end-to-end encryption, Signal or Matrix is recommended.

License

© 2026 Patrice Haltaya

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