Function parse_cose_key 

pub fn parse_cose_key(data: &[u8]) -> Result<CoseKey>

Decode a CBOR-encoded COSE_Key and return it as a CoseKey.

Both EC2 (kty = 2) and RSA (kty = 3) keys are supported. For EC2: dispatches on alg to validate crv and coordinate length — ES256 (alg = -7) requires crv = 1 and 32-byte x/y coordinates; ES384 (alg = -35) requires crv = 2 and 48-byte x/y coordinates. For RSA: validates alg == -257 and that n is at least 256 bytes.

Errors

• WebAuthnError::CborDecodeError — input is not valid CBOR.
• WebAuthnError::InvalidPublicKey — missing required fields, wrong key type, or bad curve.
• WebAuthnError::UnsupportedAlgorithm — alg is present but not a recognised value.