NeoStego

Hide data inside images and audio, and watermark your files

NeoStego does two things:

Data hiding — conceal any file inside an image or audio file, optionally encrypted. Watermarking — embed an invisible, password-keyed signature to detect unauthorized copying. It's a modernized fork of OpenStego by Samir Vaidya, adding strong authenticated encryption, detection-resistant algorithms, runtime-bundled native installers, and a new Android app — while staying format-compatible with OpenStego.

Features 🔒 Modern encryption — PBKDF2-HMAC-SHA256 (random salt, high iteration count) + AES-GCM authenticated encryption. Older OpenStego data still decrypts automatically. 🖼️ Detection-resistant hiding — RandomLSBMatch (±1 LSB matching) defeats classic statistical steganalysis; Adaptive (HILL + Syndrome-Trellis Codes) concentrates changes in textured regions to resist modern, including CNN-based, detectors. 💧 Robust watermarking — DWTSVD embeds a real multi-bit payload, recovered blindly, that survives JPEG recompression, noise, blur, resampling, brightness changes, and small crops. 🎵 Audio support — hide data in uncompressed WAV (PCM) files. 🎨 More formats — read PNG/BMP/WebP covers, preserve embedded ICC color profiles, choose JPEG quality for watermarking. 🖥️ Native desktop UX — FlatLaf light/dark themes, native OS file dialogs, drag-and-drop, password reveal. 📱 Android app — a Kotlin / Jetpack Compose client sharing the same core engine. 🧩 Full CLI — scriptable embed / extract / watermarking commands

Limitations Save and share losslessly. Hidden data lives in least-significant bits, so stego output must stay lossless (PNG for images, uncompressed WAV for audio). Re-encoding as JPEG/MP3 — including the recompression chat apps apply to "photos" — destroys the payload. Share as a file, not a photo. Capacity scales with the cover. Roughly one payload byte per ~3 image pixels (or ~8 audio samples); oversized payloads fail fast with a clear message. The content-adaptive algorithm trades capacity for security and holds less than plain LSB. The app shows usable capacity once a cover is selected. Transparency is preserved, not used. Alpha channels survive the round-trip; data is hidden only in RGB channels