dpp-crypto

Cryptographic primitives for the Odal Node Digital Product Passport system: Ed25519 key management, JWS signing and verification, JCS canonicalisation, and an AES-256-GCM encrypted keystore with Argon2id key derivation and rotation.

Pure Rust, no I/O beyond the keystore file. Not a wasm32-unknown-unknown target — the RNG requires a platform entropy source.

This crate has no workspace dependencies. Verifiable Credentials, did:web documents and status lists are dpp-vc; the per-field disclosure policy is dpp_domain::access. What remains is primitives, and nothing here needs a domain type to do its job.

When to use this crate

• You need to sign or verify DPP data with Ed25519 as a compact JWS.
• You need JCS canonicalisation so two nodes produce byte-identical payloads before signing.
• You are managing signing keys at rest — generation, rotation, revocation, archival — with encryption and integrity protection.

Example

use dpp_crypto::jws::{signer, verifier};
use dpp_crypto::keystore::KeyStore;
use serde_json::json;

fn sign_a_payload(store: &KeyStore) {
    let payload = json!({ "product": "battery", "status": "published" });
    let jws = signer::sign(store, "issuer", &payload).expect("sign");

    // The kid travels in the JWS header, so a verifier can select the right key
    // from a DID document that may list several, including rotated ones.
    let kid = verifier::extract_kid_from_jws(&jws).expect("kid present");
    assert!(!kid.is_empty());
}

KeyStore::open creates the file if it is absent, so the path is a real decision — pass a configured location outside the source tree. A complete, runnable version including keystore setup is in examples/sign_and_verify.rs:

cargo run -p dpp-crypto --example sign_and_verify

Security notes

• The keystore is protected by Argon2id key derivation with HMAC-SHA256 integrity over the stored records. It has not been externally audited.
• KeyStore::public_key and PublicKeyInfo are public so the did:web builder in dpp-vc can read public key material and revocation state. Neither exposes private key material.
• Signing uses alg: "EdDSA" with curve Ed25519, per RFC 8037.

Relationship to other crates

Minimum Rust version

1.96 (MSRV is enforced in CI)

License

Apache-2.0 — see LICENSE