c2pa-sign

c2pa-sign is a skill for Claude Code from indranilbanerjee/socialforge. It costs 124 tokens per session (2,082 once invoked), scanned A, original, MIT.

A tool for adding C2PA provenance records to AI-generated marketing assets. C2PA is an open standard that records where digital content came from and how it was created.

In plain words
What is it for?
Use it to sign SocialForge images or videos with details such as the brand, generator, timestamp, prompt, target platform, and type of AI involvement.
Why use it?
It creates a machine-readable disclosure and approval record for assets that may need AI-origin information, especially for EU distribution.

Skill for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_DATA} variable.

Part of the socialforge plugin — 20 skills, 25 commands, 5 agents shipped together

Good fit Use it to sign SocialForge images or videos with details such as the brand, generator, timestamp, prompt, target platform, and type of AI involvement.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/indranilbanerjee/socialforge/c2pa-sign
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add indranilbanerjee/socialforge --skill c2pa-sign
Clone the repo
git clone --depth 1 https://github.com/indranilbanerjee/socialforge

Made for: Claude Code.

Or install socialforge, the plugin that ships this one along with the rest of its 20 skills, 25 commands, 5 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for c2pa-sign

README.md
[![agentmods](https://agentmods.dev/badge/skills/indranilbanerjee/socialforge/c2pa-sign/github.svg)](https://agentmods.dev/skills/indranilbanerjee/socialforge/c2pa-sign)
Your own site
<a href="https://agentmods.dev/skills/indranilbanerjee/socialforge/c2pa-sign"><img src="https://agentmods.dev/badge/skills/indranilbanerjee/socialforge/c2pa-sign/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for c2pa-sign

Your own site · 80×15
<a href="https://agentmods.dev/skills/indranilbanerjee/socialforge/c2pa-sign"><img src="https://agentmods.dev/badge/skills/indranilbanerjee/socialforge/c2pa-sign.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 124 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,082 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00124 $0.02082
Opus 5 $0.00062 $0.01041
Sonnet 5 $0.00025 $0.00416
Haiku 4.5 $0.00012 $0.00208

Measured 11d ago against content hash 983751245c3a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

c2pa-sign scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/c2pa-sign/SKILL.md · 141 lines

How it starts

The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/socialforge:c2pa-sign — Embed Content Authenticity Provenance

Purpose

Context efficiency

Asset-heavy skill. Grep before Read the asset catalog (${CLAUDE_PLUGIN_DATA}/socialforge/brands/<brand>/asset-index.json) — never list the asset directory. Reference generated images / videos by path, not by loading metadata. Brand profile loads once per session.

Wraps scripts/c2pa_sign.py to add a C2PA manifest to any SocialForge-generated marketing asset. The manifest carries:

  • Machine-readable provenance trail (brand, generator name, timestamp, prompt, target platform)
  • IPTC digital-source-type vocabulary tag (TRAINED_ALGORITHMIC_MEDIA / COMPOSITE_WITH_TRAINED_ALGORITHMIC_MEDIA / HUMAN_EDITS)
  • schema.org CreativeWork assertion (author = brand organization, dateCreated, publishingPrinciples = target platform)

Why this matters: EU AI Act Article 50 applies from 2 August 2026. Generative-AI marketing content distributed in EU markets must be marked in a machine-readable format using open, interoperable standards — C2PA is the emerging backbone. Penalty: up to €15 million or 3% global annual turnover. Additional disclosure obligations apply under NY synthetic-performer law (effective June 2026) and FTC May 2026 endorsement guidance.

The resulting asset is verifiable at contentcredentials.org/verify or in any C2PA-aware viewer (Adobe Photoshop, Lightroom, Truepic, Microsoft Copilot, etc.).

C2PA spec versions relevant to SocialForge (June 2026)

  • Content Credentials 2.3 (released 9 February 2026 — launch post) added support for live video (broadcast/streaming), plain text documents, OGG Vorbis audio, large AVI video files, and EXIF Original Preservation Images. Relevant to SocialForge because:
    • Live video signing matters if you're producing Reels / TikTok / Shorts streaming content alongside the planned monthly batch.
    • EXIF Original Preservation Image format is the cleanest path for signing product photography that the brand wants to preserve through ad ops cropping.
  • C2PA Spec 2.4 (April 2026 — spec.c2pa.org/specifications/specifications/2.4) introduces the AI Disclosure Assertion (c2pa.ai-disclosure) — machine-readable AI transparency info that the EU AI Act Article 50 deployer pathway will read. When c2pa_sign.py is on a C2PA SDK ≥ 0.36 that handles 2.4, include this assertion alongside the existing IPTC + schema.org tags. The combination is what the EU Code of Practice WG1/WG2 drafts reference as the canonical machine-readable mark.
  • C2PA Trust List is now handled via the public C2PA Conformance Program — production signing certificates should come from a Conformance-Program-listed CA.

Read the full file on GitHub · 141 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 11d ago First seen · 141 lines · 124 tokens per session scan A 983751245c3a

Subscribe to this mod's changes

c2pa-sign is a skill published in the GitHub repository indranilbanerjee/socialforge (38 stars, last pushed 25d ago), licensed MIT. It adds 124 tokens to every session and 2,082 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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