c2pa-lite

c2pa-lite is a Rust library that stamps generated media with recoverable, cryptographically signed C2PA content credentials — a "this is synthetic, from this model, at this time" provenance signal. It targets the long tail of open and self-hosted image/video generators that ship no provenance today.

Install

cargo add c2pa-lite

What it does

• Wraps contentauth/c2pa-rs to build, sign, embed, and verify C2PA manifests — it does not reimplement C2PA.
• Fills C2PA's empty soft-binding slot with an OSS watermarker (default: Adobe TrustMark via ONNX) through a pluggable SoftBinder trait, so the watermark is swappable without touching the signing path.
• Exposes a 3-call surface: credential (mark + sign + embed), verify (manifest + validation + watermark decode), and recover (refetch a stripped manifest from the store).
• Supports JPEG and PNG, with experimental MP4/H.264 video via per-segment soft binding plus fragmented-MP4 hard binding.
• Signs with local PKCS#8 keys for development and KMS/PKCS#11 for production, against a documented test-anchor trust list.
• Emits a normalized JSON verdict that is wire-compatible with Adobe/CAI Verify (signed? trusted issuer? watermark decoded? recovered from store?).

Quickstart

use c2pa_lite::{credential, verify};

// Mark + sign + embed a credential into a generated image.
let signed = credential(&image_bytes, "stable-diffusion-xl", &signing_key)?;
std::fs::write("output.signed.jpg", &signed)?;

// Later, validate the asset and inspect the verdict.
let report = verify(&signed)?;
println!("signed:           {}", report.signed);
println!("trusted issuer:   {}", report.trusted_issuer);
println!("watermark decoded: {}", report.watermark_decoded);

Status

Pre-release: the first crates.io publish is still pending, so pin versions and expect the API to move before a stable release. Signing and manifest handling delegate to c2pa-rs upstream; robust watermarking is the active work, and invisible marks are removable — c2pa-lite ships adversarial decode-survival numbers and never claims to be tamper-proof.

Source

packages/c2pa-lite