SKILL.md
sign-ai-media
CLI and TypeScript library for embedding signed C2PA manifests in images and videos to label them as AI-generated.
Prerequisites
The package must be installed first. From the project root:
npm install
npm run buildAfter building, the CLI is available at node dist/cli.js or via npx sign-ai-media if installed globally.
For development without building, use npx tsx src/cli.ts instead.
Signing Media
Minimum required: input, output, and --software-agent.
npx sign-ai-media input.png output.png --software-agent "my-generator"Common signing pattern
npx sign-ai-media input.png output.png \
--software-agent "acme-image-model" \
--version "1.0.0" \
--generator "Acme Image API" \
--model "acme-diffusion-v1" \
--producer "Acme Labs" \
--prompt "A red fox in a snowy forest" \
--source-type ai-generatedWith production credentials
npx sign-ai-media input.png output.png \
--software-agent "acme-image-model" \
--certificate ./certs/signing-cert.pem \
--private-key ./certs/signing-key.pem \
--algorithm es256 \
--tsa-url "https://timestamp.example.com"Without --certificate/--private-key, the bundled development signer is used automatically (fine for local testing, not for production).
Viewing Metadata
npx sign-ai-media --view output.png
npx sign-ai-media --view output.png --json--json returns machine-readable output. Use it when piping results or inspecting fields programmatically.
CLI Flag Reference
Identity & metadata
| Flag | Description |
|---|---|
--software-agent <name> |
Required. Model, service, or pipeline name |
--version <ver> |
Software agent version |
--generator <name> |
Friendly generator name for CreativeWork |
--model <name> |
Model name |
--model-version <ver> |
Model revision |
--producer <name> |
Organization or creator name |
--claim-generator <val> |
C2PA claim_generator override |
Generation parameters
| Flag | Description |
|---|---|
--prompt <text> |
Prompt text (public metadata) |
--prompt-file <path> |
Read prompt from file |
--negative-prompt <text> |
Negative prompt text |
--negative-prompt-file <path> |
Read negative prompt from file |
--seed <value> |
Generation seed |
--scheduler <name> |
Scheduler/sampler name |
--cfg-scale <num> |
CFG scale (positive number) |
--steps <num> |
Step count (positive integer) |
--created-at <iso> |
Creation timestamp |
Source type
| Flag | Description |
|---|---|
--source-type <preset> |
Preset name (see below) |
--digital-source-type <url> |
Full IPTC URL override |
Source type presets: ai-generated, ai-edited, algorithmic, algorithmically-enhanced, composite-ai, composite, composite-capture, capture, screen-capture, human-edited, digital-art, digital-creation, software-image, data-driven, empty, ai-data.
Default is ai-generated (trainedAlgorithmicMedia).
Ingredients
| Flag | Description |
|---|---|
--ingredient <path> |
Add componentOf ingredient (repeatable) |
--parent <path> |
Add parentOf ingredient |
Training/data-mining policy (CAWG)
| Flag | Values |
|---|---|
--ai-training-use |
allowed, notAllowed, constrained |
--ai-generative-training-use |
allowed, notAllowed, constrained |
--data-mining-use |
allowed, notAllowed, constrained |
--ai-inference-use |
allowed, notAllowed, constrained |
--training-constraint-info <text> |
Explanation for constrained entries |
Signing credentials
| Flag | Description |
|---|---|
--certificate <path> |
PEM certificate path |
--private-key <path> |
PEM private key path |
--algorithm <alg> |
es256, es384, es512, ps256, ps384, ps512, ed25519 |
--tsa-url <url> |
Timestamp authority URL |
Advanced
| Flag | Description |
|---|---|
--action <name> |
C2PA action (default: c2pa.created) |
--action-description <text> |
Action description |
--action-parameters-json <json> |
Extra action parameters as JSON |
--creative-work-json <json> |
Extra CreativeWork properties as JSON |
--mime-type <mime> |
Override MIME type |
--remote-manifest-url <url> |
Store manifest remotely |
--no-embed |
Don't embed manifest in output |
--vendor <name> |
Manifest label vendor prefix |
Viewer flags
| Flag | Description |
|---|---|
--view <file> |
View mode (no signing) |
--json |
JSON output for --view |
--verify-trust |
Verify trust chain |
--trust-anchors <path> |
PEM trust anchors |
--fetch-remote-manifest |
Fetch remote manifests |
--no-fetch-remote-manifest |
Skip remote manifests |
TypeScript API
import { signAiGeneratedMedia, viewAiGeneratedMedia } from "sign-ai-media";
await signAiGeneratedMedia({
input: "input.png",
output: "output.png",
metadata: {
softwareAgent: "my-generator",
version: "1.0.0",
generator: "My Generator",
model: "my-model-v1",
producer: "My Org",
prompt: "A sunset over mountains",
},
});
const result = await viewAiGeneratedMedia({ input: "output.png" });Supported formats
PNG, JPEG, WebP, AVIF, TIFF, MP4, MOV, AVI. Use --mime-type for unusual extensions.
Workflow guidance
- Signing then verifying: always run
--viewon the output after signing to confirm the manifest was embedded correctly. - Batch signing: loop over files in a shell script; each call is independent.
- Prompt from file: use
--prompt-filefor long prompts instead of inline--promptto avoid shell quoting issues. --certificateand--private-keymust always be provided together. Omitting both uses the bundled dev signer.--source-typeand--digital-source-typeare mutually exclusive.--promptand--prompt-fileare mutually exclusive (same for--negative-prompt/--negative-prompt-file).