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EPUB content provenance

Content provenanceContent provenance: The record of where a piece of content came from and how it changed, carried with the content itself. for EPUB files is a signed C2PA manifestC2PA manifest: The signed label itself: a small package inside a file that records who signed it, what they declared and how to check it. inside the file. Anyone can check who signed it and whether it changed, for free.

Start signing freeCheck a EPUB file
A file holds a signed label in four layers: who signed it, what they declared including AI use, a fingerprint of the content, and a signature that seals them together.
The label sits inside the file. It names the signer, carries what they declared, fingerprints the content, and is sealed by a signature.
File
.epub, MIME typeMIME type: The standard name for a file format, such as image/jpeg or audio/wav, that software uses to decide how to read a file. application/epub+zip
Where the label sits
Inside the file, in its own entry inside the ZIP package that holds the book.
Standard
C2PAC2PA: The Coalition for Content Provenance and Authenticity: the group that publishes the open standard for content labels., the open standard for content labels.
Made for
Ebooks, Digital magazines, Journals, Self-published books

What Encypher supports for EPUB

  • SignSupported

    Encypher signs EPUB files under C2PA 2.2 and 2.4.

  • CheckSupported

    Free in the browser checker, with no account.

  • Formal conformanceNot yet

    Not in our formal conformance record. That record is a narrower test than signing and checking.

How to check a EPUB file

  1. Open the free checker.

    It runs in your browser. No account needed.

    Open the checker

  2. Add your EPUB file.

    Drop it in or pick it from your device.

  3. Read the result.

    It shows who signed and what they declared, such as AI use. It also shows if the file changed.

Where the label sits in a EPUB file

The file is a ZIP package of entries. The label is one entry of its own.

In a DOCX, EPUB, ODT or OXPS package, the label is one entry among the files inside the package.
A EPUB file keeps the label in its own entry inside the ZIP package that holds the book.

EPUB is the open ebook format. Publishers and libraries use it for books, magazines and journals.

What keeps the label on a EPUB file

Four of the five answers a provenance check can give: Verified, Modified after signing, Issuer not recognized, and No provenance found. The fifth is Could not verify.
A check reports who signed and whether the content changed. It never says whether the content is true.
  • Sending and saving the file keep the label.
  • Changing the text after signing shows as a change.
  • Printing, scanning or exporting to another format makes a new file without the label.

For engineers

Show the technical detail
Embedding
JUMBF manifest store in the META-INF/content_credential.c2pa entry of the ZIP package
Accepted MIME types
application/epub+zip
Signing versions
C2PA 2.2, 2.4
Verification
Any version. The checker reads any C2PA manifest it can parse, and the report names the version it checked against.
curl -X POST https://api.encypher.com/api/v1/sign/media \
  -H "Authorization: Bearer $ENCYPHER_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -F "file=@example.epub" \
  -F "title=My EPUB file" \
  -F "action=c2pa.created"

Support rows come from the live API capability matrix. Full reference: C2PA media types.

Keep reading

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