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What is content provenance?

Content provenanceContent provenance: The record of where a piece of content came from and how it changed, carried with the content itself. is a signed label inside a file or text. It shows who signed it, what they declared, including any AI use, and whether it changed since. Anyone can check it, free.

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Send a file to the signing API, get it back signed with the label inside, and anyone can check it for free without an Encypher account.
Signing is one API call. Checking is free and needs no account.
Open standard
Built on C2PAC2PA: The Coalition for Content Provenance and Authenticity: the group that publishes the open standard for content labels., the open standard from a group that includes Adobe, Microsoft and the BBC. Encypher wrote its part for text.
Formats
75+ formats for signing and verification, from plain text to PDF and Word.
Checking
Free, with no account.
What it shows
Who signed, what they declared, and whether it changed. Never whether the content is true.

How it works: sign, carry, check

An article appears and a key signs it. A gold thread sews the label round the article and the blue Encypher badge lands on its corner. The words read: Sign it, then The label goes inside. A magnifier glides over the badge, the badge lifts and pulses, and a check mark appears. The words read: Anyone can check it, free.

Sign once. Anyone can check it, free.

  1. Sign it.

    When you publish, Encypher adds a label with a digital signatureDigital signature: Math that shows which key signed something and that it has not changed since. Any edit to the signed bytes breaks it.: who you are, the time, and what you declare, including any AI use.

  2. It travels with the work.

    In a file, the label sits inside the file. In text, it rides in characters readers never see.

    How it works in text

  3. Anyone checks it.

    The free checker shows who signed and whether anything changed since.

    What a check tells you

Labels for text, images, audio, video and documents

The idea is the same everywhere. Where the label sits depends on the kind of file.

All formats, by kind of file

Our API lists 88 file formats. Encypher can both sign and check 79 of them. Pick a kind of file to see each one and its media 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..

Images: 15 formats, live from our API.
FormatFile endingSignCheckMedia type
JPEG.jpg, .jpegYesYesimage/jpeg, image/jpg
PNG.pngYesYesimage/png
WebP.webpYesYesimage/webp
TIFF.tiff, .tifYesYesimage/tiff
AVIF.avifYesYesimage/avif
HEIC.heicYesYesimage/heic
HEIF.heifYesYesimage/heif
HEIC Sequence.heicsYesYesimage/heic-sequence
HEIF Sequence.heifsYesYesimage/heif-sequence
SVG.svgYesYesimage/svg+xml
DNG.dngYesYesimage/x-adobe-dng
GIF.gifYesYesimage/gif
JPEG XL.jxlYesYesimage/jxl
Other TIFF-based imagesVariousYesNoimage/x-tiff-based
Other RIFF-based imagesVariousYesNoimage/x-riff-based
Labels on images

When a site strips the label

Some sites rebuild files on upload and drop the label. A hidden watermarkWatermark: A mark placed in the content itself, visible or hidden, so it can be found again after the file is copied. added at signing can still point back to the signed record. The check reports that as recovery.

A file signed with a label and a watermark loses its label when a site strips metadata; a checker finds the watermark, which points back to the signed record, shown as recovered.
If a site strips the label, a supported watermark can lead back to the signed record. The result says it was recovered.
How recovery works

How it compares

A signed text mark gives a yes or no anyone can check, valid or changed; a statistical pattern runs through a model and gives a probability, such as 72 percent likely AI.
A cryptographic mark gives a checkable answer. A statistical pattern gives a probability.
AI detectors
An AI detectorAI detector: A model that guesses whether content was made by AI and returns a probability, not proof. guesses from patterns and gives a score. A label is a signed record, so it either checks out or it does not. Provenance vs. detection
Blockchain timestamps
A blockchain timestampBlockchain timestamping: Writing a file's hash to a public ledger to show it existed at a given time. stays on the chain. A label travels inside the copy, so whoever has the copy can check it. Provenance vs. blockchain

Questions

What is content provenance?
A signed record of where a piece of content came from. It names who signed it, what they declared, including any AI use, and whether the content changed since.
How is it different from normal metadata?
Normal metadataMetadata: Data stored beside the content in a file, such as author, camera or date. Many tools strip it when they copy or upload a file., like a photo's camera details, is plain text anyone can edit. A provenance label is signed, so any change to it or to the content shows up in a check.
Does a label prove the content is true?
No. It shows who stands behind the content and whether it changed. Whether the content is accurate is a separate question.
Does the label survive copy and paste?
In text, yes, as long as the hidden characters are copied too. In files, the label stays when the file is copied whole. Some sites rebuild files on upload and drop it.
Does the EU AI Act require it?
The EU AI ActEU AI Act: The European Union's law on artificial intelligence, which includes rules for marking AI-made content.'s Article 50Article 50: The EU AI Act rule that AI-made content be marked in a form software can read, and deepfakes disclosed. asks for machine-readable markingMachine-readable marking: A label software can read that says content was made or changed by AI. of AI output. The duties apply August 2, 2026 for new systems, December 2, 2026 for systems already on the market. A label can carry that marking. Your counsel decides what else applies to you.
How do I add labels to my content?
Use the REST APIAPI: Application programming interface: a way for one program to ask another to do a job, such as sign a file. or the WordPress plugin. Publishers sign free through the Publisher Program. Companies marking AI output use a Mark plan.

For engineers

Show the technical detail

What a check does

A C2PA manifest is a JUMBF container of CBOR claims and assertions, signed with COSE under an X.509 certificate. A check extracts the manifest, validates the signature and the certificate chain against the C2PA Trust List, then recomputes the hard-binding hash over the content and compares it with the signed one. For text, the standard carries the manifest in invisible Unicode characters inside the text itself.

C2PA 2.3, with the standard for unstructured text, was published on January 8, 2026. Encypher authored C2PA's standard for unstructured text, published as Section A.7 in C2PA 2.3 and carried forward as Section A.8 in C2PA 2.4.

The capabilities endpoint

The format list above is read from GET /api/v1/capabilities/formats and refreshed hourly. It accepts 103 MIME type spellings: 97 for signing and 94 for verification, grouped under 88 canonical formats. Alias spellings, such as image/jpg, are listed beside their canonical type.

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