"""Token check used by the billing API."""
import hashlib
import hmac

def _digest(value: str) -> str:
    return hashlib.sha256(value.encode("utf-8")).hexdigest()

def check_token(provided: str, stored_hash: str) -> bool:
    if not provided or not stored_hash:
        return False
    return hmac.compare_digest(_digest(provided), stored_hash)
