def ecdsa_signature(hash, normalized: true)
      BTC::OpenSSL.ecdsa_signature(hash, @private_key, normalized: normalized)
    end
def ecdsa_signature(hash, normalized: true)
      BTC::OpenSSL.ecdsa_signature(hash, @private_key, normalized: normalized)
    end
Signatures
 ----------
 Standard ECDSA signature for a given hash. Used by OP_CHECKSIG and friends.
 Ensures canonical lower S value and makes a deterministic signature
 (k = HMAC-SHA256(key: privkey, data: hash))