In an example, a computing device is described. The computing device comprises an interface to receive a request from a signer for a state. The state is to be used as an input to generate a key under a stateful signature scheme. The computing device further comprises a processor. The processor is to identify an available state that the signer is authorized to use in response to the request received via the interface. The available state is identified from a set of states that can be used by the signer to maintain statefulness of the stateful signature scheme. The processor is further to instruct a reply to be sent to the signer via the interface. The reply comprises an indication of the state that the signer is authorized to use.