pub fn extract_key_from_spki(spki_der: &[u8]) -> Result<&[u8], Error>Expand description
Extract raw public key bytes from a SubjectPublicKeyInfo DER blob.
The SPKI DER contains a BIT STRING that holds the raw key material (uncompressed point for P-256, 32-byte key for Ed25519, etc.). This walks the DER structure to locate the BIT STRING and returns its content (minus the leading unused-bits byte).