SEAL is a Secure Evidence Attribution Label. It permits signing media for attribution. The specifications are at: https://github.com/hackerfactor/SEAL
This is an implementation of SEAL in C.
This code:
- Generates keys. The private key should be kept private. The public key is ready to be uploaded to your DNS TXT record.
- Sign files using the private key. It also supports using a remote signing service.
- Validating signatures. This only requires DNS access. For testing/debugging, you can specify the public key DNS TXT file that you generated.
See the BUILD file for compiling and usage.
This code currently supports static-files only. It does not support streaming data. (The SEAL protocol supports streaming data, but this implementation does not (yet).)
| Image Format | Read Support | Write Support |
|---|---|---|
| JPEG | Yes | Yes |
| PNG | Yes | Yes |
| GIF | Yes | Yes |
| WEBP | Yes | Yes |
| HEIC | Yes | Yes |
| AVIF | Yes | Yes |
| PNM/PPM/PGM | Yes | Yes |
| SVG | Yes | Yes |
| TIFFⁱ | Yes | Yes |
| DICOM | Yes | Yes |
| BMP | No (no metadata support) | No (no metadata support) |
| FAX | No | No. Seriously, just no. |
ⁱ TIFF includes many camera-raw formats, including Adobe Digital Negative (DNG), Canon CRW and CR2, Hasselblad 3FR, Kodan KDC, Leica RAW, Nikon NEF, Panasonic Raw, Sony ARW, and many more.
| Audio Format | Read Support | Write Support |
|---|---|---|
| AAC | Yes | Yes |
| AVIF | Yes | Yes |
| M4A | Yes | Yes |
| MKA | Yes | Yes |
| MP3 | Yes | Yes |
| MP3+ID3 | Yes | Yes |
| MPEG | Yes | Yes |
| WAV | Yes | Yes |
| Video Format | Read Support | Write Support |
|---|---|---|
| MP4 | Yes | Yes |
| 3GP | Yes | Yes |
| AVI | Yes | Yes |
| AVIF | Yes | Yes |
| HEIF | Yes | Yes |
| HEVC | Yes | Yes |
| DIVX | Yes | Yes |
| MKV | Yes | Yes |
| MOV/Quicktime | Yes | Yes |
| MPEG | Yes | Yes |
| WEBM | Yes | Yes |
| Document Format | Read Support | Write Support |
|---|---|---|
| Yes | Yes | |
| XML | Yes | Yes |
| HTML | Yes | Yes |
| Plain Text | Yes | Yes |
| OpenDocument (docx, pptx, etc.) | Coming soon | Coming soon |
| Container Format | Read Support | Write Support | About |
|---|---|---|---|
| EXIF | Yes | Yes: See Manual Signing | EXIF is a standard format for storing metadata. It is often found in JPEG, PNG, and a few other file formats. SEAL supports all top-level EXIF records. (Nested EXIF records are unsupported due to the ambiguous scope.) |
| XMP | Yes | Yes: See Manual Signing | XMP is a standard text-based format for storing metadata. It may appear in a wide range of files. SEAL supports all top-level XMP records. (Nested XMP records are unsupported due to the ambiguous scope.) |
| RIFF | Yes | Yes | The Resource Interchange File Format (RIFF) is a container format used by WAV, AVI, and a few other (less common) media files. SEAL supports all RIFF-based files. |
| ISO-BMFF | Yes | Yes | ISO's Base Media File Format (BMFF, also called ISO-14496) is a container format used by MP4, 3GP, HEIF, HEIC, AVIF, DIVX, and many other common media files. SEAL supports all ISO-MBFF files. |
| Matroska | Yes | Yes | Matroska is a flexible container format used by WebM, MKV (video), and MKA (audio). SEAL supports all Matroska-based media files. |
| ZIP | Coming soon. | Coming soon. | ZIP is an archive container that can hold multiple files. The OpenDocument formats use ZIP. |
This is not every file format that sealtool supports! Many formats are based on other formats. (CR2 is based on TIFF, DIVX is based on RIFF, etc.). Similar formats are likely already supported. sealtool will only parse files when it recognizing the file format.
Have a format you need that isn't supported? Let us know!