Struct RingSigner 

pub struct RingSigner { /* private fields */ }

CaseSigner backed by the p256 crate’s RFC 6979 deterministic ECDSA.

The name RingSigner is kept for API stability (this type was introduced in M4.1). Key generation still uses ring ([Self::generate]), but signing uses p256::ecdsa::SigningKey (RFC 6979 deterministic) and the public key is derived from the same p256 signing key. This enables byte-for-byte test-vector parity with @noble/curves (JavaScript) as captured by cargo xtask capture-case.

Use Self::from_pkcs8 to load existing keys (e.g., from a fabric store), or Self::generate in tests to mint a fresh keypair.

Implementations

impl RingSigner

pub fn from_pkcs8(pkcs8_bytes: &[u8]) -> Result<Self>

Construct from PKCS#8 v1 encoded private key bytes.

Parses the PKCS#8 DER bytes using p256::ecdsa::SigningKey, which also derives the matching public key. The 65-byte SEC1-uncompressed public key is extracted from the p256 verifying key.

Errors

Returns Error::SigningFailed with SignerError::Internal if the bytes are not a valid PKCS#8-encoded P-256 key.

pub fn generate() -> Result<(Self, Vec<u8>)>

Generate a fresh ECDSA-P256 keypair. Returns the signer plus the PKCS#8 bytes so the caller can persist them.

Key generation uses ring’s EcdsaKeyPair::generate_pkcs8 for its well-audited RNG plumbing. The resulting PKCS#8 is then loaded via from_pkcs8 so that signing uses the deterministic p256 path.

Errors

Returns Error::SigningFailed with SignerError::Internal if the OS RNG or key-generation step fails (extremely unlikely in practice).

Trait Implementations

impl CaseSigner for RingSigner

fn sign_p256_sha256(&self, message: &[u8]) -> Result<[u8; 64], SignerError>

Sign message using RFC 6979 deterministic ECDSA-P256-SHA256.

Uses p256::ecdsa::SigningKey::sign which follows RFC 6979 for nonce generation (same algorithm as @noble/curves in JavaScript), enabling byte-for-byte reproducible test vectors captured by cargo xtask capture-case.

The signature is low-s normalized (s ≤ n/2), matching @noble/curves behavior. Both s and n - s are valid ECDSA signatures; this ensures the Rust output is byte-identical with matter.js.

The returned signature is in IEEE P1363 compact format (raw r||s, 64 bytes), which is the Matter wire format for ECDSA signatures.

Errors

Returns SignerError::Internal on signing failure (not expected for valid keys and any message length).

fn public_key(&self) -> &PublicKey

The 65-byte SEC1-uncompressed P-256 public key matching the NOC.

impl Debug for RingSigner

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.