'Attaches a policy to the specified key.
:type key_id: string
:param key_id: Unique identifier of the key. This can be an ARN, an
alias, or a globally unique identifier.
:type policy_name: string
:param policy_name: Name of the policy to be attached. Currently, the
only supported name is "default".
:type policy: string
:param policy: The policy, in JSON format, to be attached to the key.'

def put_key_policy(self, key_id, policy_name, policy):

    params = {'KeyId': key_id, 'PolicyName': policy_name, 'Policy': policy}
    return self.make_request(action='PutKeyPolicy', body=json.dumps(params))
