/sketch

Provenance and Disclosure

Purpose

Every AI-generated image needs a paper trail: who made it, what model, what prompt, what date, what permissions. C2PA Content Credentials, SynthID watermarks, and EXIF AI-disclosure tags are the 2026 standards. Without them, commercial use, journalism, regulated industries, and EU AI Act compliance all break. This reference defines the embedding, verification, and takedown-response protocol.

Scope Boundary

• IN scope: C2PA Content Credentials, SynthID, EXIF / XMP AI tags, watermark verification, takedown-request response, platform-specific disclosure norms.
• OUT of scope: image generation itself (generate), prompt design (prompt / cinematic), upscaling (upscale), policy refusals (policy), copyright case-by-case legal review (delegate to clause).

Core Concepts

Why Provenance Matters in 2026

A 2025 image with no provenance is a 2026 liability.

The Three Standards

These complement each other: C2PA for chain-of-custody, SynthID for tamper-evident watermarking, EXIF for legacy compatibility.

C2PA Content Credentials

The Coalition for Content Provenance and Authenticity (Adobe, Microsoft, BBC, NYT, etc.) ships an open standard (v2.0 in 2026):

Implementation:

# Python c2patool example
from c2pa import builder

builder.add_assertion("c2pa.actions", {
    "actions": [{"action": "c2pa.created"}]
})
builder.add_assertion("c2pa.training_data", {
    "training_data_used": "Imagen-4 base model, March 2026 checkpoint"
})
builder.sign(certificate, private_key, "output.jpg")

Verification: open in Photoshop / Premiere / VLC 4+ — Content Credentials panel shows the manifest. Online: contentcredentials.org/verify.

SynthID

Google's invisible-watermark system (DeepMind 2023, expanded 2024-2026):

For Imagen / Nano Banana 2 outputs, SynthID is always on. Disclosure is mandatory; verification gives audiences a way to check.

EXIF / XMP AI Tags

Standard fields for AI-generated images (IPTC and Adobe XMP working groups, 2024+):

XMP-iptcExt:DigitalSourceType = "trainedAlgorithmicMedia"
XMP-iptcExt:DigitalSourceFileType = "image/jpeg"
XMP-photoshop:Credit = "AI generated by Nano Banana 2"
XMP-photoshop:Source = "gemini-3.1-flash-image@google"
EXIF:Software = "Gemini 3.1 Flash Image / 2026-08-19"
EXIF:UserComment = "Prompt summary: portrait, studio lit"

Read by Photoshop, Lightroom, DAM systems (Adobe Bridge, Photo Mechanic), social-platform ingestors.

Disclosure Strings (Per Platform)

When in doubt: disclose explicitly in caption + metadata.

Distribution Pipeline

Generate image
  ↓ embed C2PA + SynthID + EXIF
Sign with project certificate
  ↓
Optional: edit in Photoshop (preserves C2PA chain)
  ↓
Export final
  ↓ verify provenance preserved
Distribute with caption disclosure
  ↓
Maintain takedown-ready archive

Each step preserves provenance. Stripping metadata at export breaks the chain.

Takedown / Appeal Response

When a platform flags an AI image incorrectly or correctly:

Maintain a takedown response log: each event with date, platform, claim, evidence provided, outcome.

Likeness / Public Figure / Minor Cases

Provenance includes attestation of training-data and likeness rights:

Sketch's policy Recipe handles refusals; provenance documents what is permitted.

Long-Term Archive

Keep for 10+ years (or jurisdictional limits):

• Original generation API response (raw bytes).
• Prompt text + parameters.
• C2PA manifest.
• Final signed export.
• Distribution log (where used, when, captioned how).
• Takedown / appeal log.

Storage: S3 with object lock / GCS retention policy / cold archive.

Verification Tools

When NOT to Use Provenance Embedding

Default: embed by default. Skip only with documented reason.

Anti-Patterns

Workflow

1. Choose provenance standards — C2PA (mandatory) + SynthID (auto for Google) + EXIF / XMP (mandatory).
2. Set up project certificate — for C2PA signing (per-org or per-project).
3. Configure generation pipeline — embed C2PA at first export.
4. Document model + prompt in C2PA assertions and EXIF UserComment.
5. Preserve manifest through edits — Photoshop / Premiere honor C2PA chain.
6. Verify final export — open in c2patool / contentcredentials.org.
7. Apply platform disclosure per distribution channel.
8. Build long-term archive — original + manifest + distribution log.
9. Document takedown-response template for likely scenarios.
10. Quarterly audit — re-verify a sample; check certificate validity.

Output Template

provenance_setup:
  standards:
    c2pa:
      enabled: yes
      certificate_id: org-aether-2026
      certificate_expires: 2027_01_01
    synthid:
      enabled: auto_via_google
      verifier: google_synthid_detector
    exif_xmp:
      enabled: yes
      digital_source_type: trainedAlgorithmicMedia
      software: "Gemini 3.1 Flash Image"
  generation_chain:
    model: gemini-3.1-flash-image
    model_version: 2026-08-19
    prompt_summary_in_xmp: yes
    full_prompt_in_archive: yes
  edit_chain:
    photoshop_preserves_c2pa: yes
    final_export_preserves_manifest: yes
  distribution:
    platforms:
      - meta: c2pa_auto_label_yes
      - x: manual_disclosure_required
      - youtube: synthetic_content_toggle
      - linkedin: caption_disclosure
      - adobe_stock: c2pa_required
      - getty: REJECTED_does_not_accept_ai
  archive:
    storage: s3_with_object_lock
    retention_years: 10
    contents: [api_response, prompt, manifest, signed_export, distribution_log]
  takedown_response:
    template: documented
    log_location: archive/takedown_log.csv
  audit_cadence: quarterly

Anti-Patterns

• Generation without C2PA — provenance broken at the source.
• Stripping EXIF at export "to save space" — destroys evidence chain.
• Generic "AI generated" disclosure without model name — insufficient for platforms with strict policies.
• Public-figure / minor depiction without rights documentation.
• Long-term archive missing — cannot defend in regulatory inquiry.
• Trust unsigned third-party images claiming provenance — forgery risk.
• Skip SynthID detection when ingesting external content.
• Caption-only disclosure (no metadata) — caption can be edited away.
• Re-encoding through tools that don't preserve C2PA (older ImageMagick, naive ffmpeg).
• Shipping certificate that's expired — manifests verify as untrusted.
• Per-asset certificates instead of org-level — hard to manage.
• No takedown-response log — same incident recurs.
• Metadata fields with conflicting / inconsistent claims — flags forgery suspicion.
• Treating C2PA as enough on its own — pair with SynthID + EXIF for resilience.

Deliverable Contract

A provenance setup is complete when:

• C2PA + SynthID (where applicable) + EXIF / XMP enabled.
• Project certificate active and not near expiry.
• Generation pipeline embeds manifest at first export.
• Edit chain preserves manifest through Photoshop / etc.
• Final export verified at contentcredentials.org.
• Platform disclosure per distribution channel.
• Long-term archive populated with all artifacts.
• Takedown-response template documented.
• Quarterly audit scheduled.

References

• C2PA specification — c2pa.org/specifications.
• Content Authenticity Initiative — contentauthenticity.org.
• contentcredentials.org/verify — public verification UI.
• Google SynthID — deepmind.google/technologies/synthid.
• Adobe Content Credentials — helpx.adobe.com/firefly/using/content-credentials.
• Project Origin (BBC) — projectorigin.org.
• IPTC Photo Metadata Standard 2024.
• EU AI Act Regulation (EU) 2024/1689 — Articles 50-52 on synthetic content disclosure.
• US AI EO 14110 (2023) and follow-on state laws.
• Truepic — truepic.com (mobile capture-to-verify).
• Reuters / AP / NYT AI-image policies (2024-2026 public statements).
• Adobe Stock / Getty / Shutterstock AI policies.
• DeepMind, SynthID: Identifying AI-generated content (2023 paper).
• W3C XMP Specification.