matter-cert 0.1.0

Matter protocol certificate parsing and chain validation.
Documentation

matter-cert

Matter protocol certificate format — parsing, serialisation, X.509 DER conversion, signature verification, and chain validation. Part of the matter-rust workspace.

Scope

Implements Matter Core Specification §6.5: a TLV-encoded variant of X.509 used for both attestation chains (DAC → PAI → PAA) and operational chains (NOC → ICAC → RCAC). This crate covers reading and validating Matter certs; issuing new certs lives in higher milestones.

  • TLV parser + serialiser (round-trip byte-exact)
  • Distinguished-name attributes including Matter-specific OIDs
  • Extension parsing (BasicConstraints, KeyUsage, ExtKeyUsage, SKI, AKI)
  • ECDSA-P256-SHA256 public-key extraction
  • X.509 DER TBSCertificate conversion (byte-identical to matter.js)
  • Signature verification via ring
  • Chain validation against configurable trust anchors

Status

Pre-release (0.1.0-pre). Feature-complete; API claimed stable; not yet on crates.io. Cross-verified against matter.js for byte-level compatibility on a 3-tier RCAC/ICAC/NOC chain.

See TODO-1.0.md for known gaps before any 1.0 release (notably: connectedhomeip cross-verification and CSA test PAA bundle).

Minimal example

use matter_cert::{
    CertificateChain, MatterCertificate, MatterTime, TrustAnchor, TrustedRoots,
};

let rcac = MatterCertificate::from_tlv(&std::fs::read("rcac.bin")?)?;
let icac = MatterCertificate::from_tlv(&std::fs::read("icac.bin")?)?;
let noc = MatterCertificate::from_tlv(&std::fs::read("noc.bin")?)?;

let mut roots = TrustedRoots::new();
roots.add(TrustAnchor::from_root_cert(&rcac));

let chain = CertificateChain::new(&[noc, icac]);
let now = MatterTime::from_unix_secs(1_750_000_000);
chain.validate(&roots, now)?;
// Ok(()) means: every cert is time-valid, the issuer/subject chain
// is structurally sound, every signature verifies, and the top cert
// anchors against rcac.

Cryptographic primitives

This crate does not implement crypto primitives. It delegates to ring for ECDSA-P256-SHA256 signature verification. ASN.1 DER encoding uses der.

Cross-verification

MatterCertificate::to_x509_tbs_der() produces bytes byte-identical to matter.js's Certificate.asUnsignedDer(). This parity is enforced in CI against a captured 3-tier RCAC/ICAC/NOC chain. Future work adds cross-verification against project-chip/connectedhomeip (see TODO-1.0.md).

License

Apache 2.0. See LICENSE.