A C++ steganography / data-embedding experiment that stores multiple arbitrary files in the low-order bits of image pixels, audio samples and 3D vertex data. Built with raylib and raygui, it includes a bit-depth preview for exploring the trade-off between capacity and carrier distortion.
Windows x64: Download v1.3.
Actual application rendering with a procedurally generated image carrier, BitDepth 2 and two files in the container.
Load a carrier, choose how many low-order bits to use, preview the changes, then open or create a container. Drop files into the right-hand panel and save a modified carrier. Reopen that output at the same bit depth to recover and export its files.
This is a personal R&D experiment in binary representation and serialization. It is not encryption and provides no cryptographic protection for sensitive data.
| Carrier | Verified input | Output | Storage units and limits |
|---|---|---|---|
| Image | PNG, JPG, JPEG | <name>_mod.png |
Image converted to RGBA; low bits of each channel byte, depth 1–8 |
| Audio | WAV, mono/stereo; 8/16/32-bit input fixtures | <name>_mod.wav |
Decoded/converted to 16-bit PCM, preserving channel count and sample rate; depth 1–16 |
| 3D model | OBJ | <name>_mod.obj |
Low bits of IEEE-754 vertex-position floats; first mesh only, including export |
PNG and WAV outputs avoid lossy re-encoding. MP3 is not offered in the UI because its input path has not been validated. Audio format preservation is limited to the normalized 16-bit representation.
With one payload bit per byte, only the least significant bit changes:
Original byte: 11010110
Payload slot: 1101011X
For a carrier with N elements and B available bits per element:
capacityBytes = floor(N × B / 8)
An image element is one channel byte; an audio element is one 16-bit sample, including each channel; a model element is one 32-bit float component. A 12-bit audio setting, for example, uses a repeating [8, 4] byte-depth pattern. BitStream traverses those physical byte slots, skipping zero-depth bytes and preserving all other bits.
Bounds checks reject oversized writes and lengths/counts that exceed remaining carrier storage before allocating payload buffers. A container that exactly fills the available capacity is valid.
All integers are unsigned 64-bit values, serialized little-endian. Strings and file data are byte sequences; no compression or encryption is applied.
| Field | Encoding |
|---|---|
| Marker | 9 literal bytes: CONTAINER |
| File count | 8 bytes |
| Each file's filename length | 8 bytes |
| Filename | The stated number of bytes |
| Data length | 8 bytes |
| File contents | The stated number of bytes |
Total size is 17 + sum(16 + filenameBytes + dataBytes). The capacity display and write checks include the marker and every metadata field. The marker identifies the format; it does not authenticate the data or detect all corruption.
The slider fills the selected low-order bits with pseudorandom preview values. This shows image degradation, audio/waveform changes or geometric distortion before embedding. The preview RNG is a small xorshift generator used for noise.
BitDepth 0 previews the original carrier only. Open and Save are disabled/rejected at zero. Change the depth back to the value used when saving before opening an existing container. Actual payloads can produce different distortion from the noise preview.
The first mesh's float components act as the carrier. The OBJ exporter writes finite coordinates with std::numeric_limits<float>::max_digits10 precision and classic-locale decimal formatting. Disk round-trips at depths 1, 2, 4, 8, 12 and 16 verified both the float bytes and recovered multi-file payload through raylib's OBJ loader.
The app works with triangle-expanded OBJ geometry as loaded by raylib. Geometry clones own their buffers and independent default materials; imported material/texture appearance is not preserved by the geometry-only export. High depths can severely distort geometry, and writes producing NaN/Inf coordinates are rejected. Arbitrary re-export, vertex reordering, mesh optimization or editing by another tool can destroy the payload.
Tested on Windows x64, with Visual Studio 2026 / MSVC 14.50, raylib 6.0, bundled raygui 4.0, Premake and C++17. The first build downloads the pinned raylib 6.0 release. The Windows script finds an installed Visual Studio C++ toolchain; VS 2022 generation remains available, but that toolchain was not validated here.
Install Visual Studio's Desktop development with C++ workload and a Windows SDK, then run from the repository root:
build-VisualStudio2022.bat Debug
build-VisualStudio2022.bat ReleaseThe script name is retained for existing workflows; it builds the target and copies runtime resources into bin/<configuration>/resources/. Run bin/Release/SecretFile.exe from any working directory with that resource folder beside it. The C/C++ runtime is linked statically.
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\test.ps1 -Configuration Debug
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\test.ps1 -Configuration Release
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\package.ps1package.ps1 creates dist/SecretFile-windows-x64.zip with the executable, required runtime resources, usage notes and licenses. It excludes PDB/IDB files and static libraries. MinGW generation is retained in build-MinGW-W64.bat; MinGW, Linux and macOS builds have not been validated.
Tests use no additional test framework. Coverage details include the standalone bit/container core, PNG/WAV/OBJ disk round-trips, malformed data, output paths and UI resource lifecycle. Debug and Release tests pass; AddressSanitizer also passed for the project's integration code linked against the raylib library.
- Drop a supported carrier into the main view.
- Set a nonzero BitDepth; Open reads an existing container or creates an empty one if no marker is found. Malformed marked containers report an error.
- Drop arbitrary files into the right panel. Del removes an entry; the mouse wheel scrolls long lists.
- Save writes
<name>_mod.png,.wavor.objbeside the source carrier, leaving the source unchanged. Saving again replaces that modified output. - Reopen the output at the same depth and press Exp to extract an entry into
<carrier-name>_extracted/, beside the carrier. Stored paths are reduced to a safe filename; existing files/links are refused.
This experiment does not hide or protect its metadata, authenticate contents or provide cryptographic security. Recompression, conversion, editing, resampling and geometry processing can destroy embedded data. A correct marker does not prove that a payload is intact. Audio/model byte traversal currently requires a little-endian host and 32-bit IEEE-754 floats.
Carrier parsing also depends on raylib's format loaders. This is an experimental desktop tool, not a hardened parser or a production security product.
SecretFile code: MIT. Bundled dependencies and assets retain their own terms; see third-party notices.