SFNT Content Provenance
Sign, embed, and verify C2PA manifests in SFNT files (.sfnt)
What Is SFNT Provenance?
SFNT container format underlying both OTF and TTF fonts. SFNT provenance covers the base font container format.
With Encypher, SFNT files carry their own cryptographic proof of origin. A C2PA manifest is embedded directly into the file, recording who created it, when, and whether it has been modified. Anyone can verify a signed SFNT file for free, without authentication.
How C2PA Manifests Are Embedded in SFNT Files
- MIME Type
- font/sfnt
- File Extensions
- .sfnt
- Embedding Method
- Custom JUMBF/COSE structural embedding in SFNT font container tables
- Container Type
- Custom JUMBF/COSE
- Verification Pipeline
- Custom JUMBF/COSE structural verification (Encypher implementation)
The C2PA manifest contains a JUMBF (JPEG Universal Metadata Box Format) store with COSE-signed claims. For SFNT files, the manifest is stored using custom jumbf/cose structural embedding in sfnt font container tables. The signing process does not alter the font content itself. The manifest is metadata, not a modification of the content.
Use Cases for SFNT Provenance
- Font containers
- Font tooling
- Cross-format font provenance
How to Sign SFNT Content with Encypher
SFNT signing is available at the Enterprise tier through the unified /sign/media API endpoint. Upload your SFNT file, and the API returns a signed copy with an embedded C2PA manifest.
curl -X POST https://api.encypher.com/api/v1/sign/media \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@example.sfnt" \ -F "title=My SFNT Content" \ -F "action=c2pa.created" \ -o signed.sfnt
Verify SFNT Provenance (Free)
Verification is free and requires no authentication. Any third party can verify a signed SFNT file to confirm its origin, check for tampering, and read the embedded rights information.