Systems and methods for authentication generate keys from secret credentials shared between authenticating parties and authenticators. Generation of the keys may involve utilizing specialized information that, as a result of being used to generate the keys, renders the generated keys usable for a smaller scope of uses than the secret credential. Further, key generation may involve multiple invocations of a function where each of at least a subset of the invocations of the function results in a key that has a smaller scope of permissible use than a key produced from a previous invocation of the function. Generated keys may be used as signing keys to sign messages. One or more actions may be taken depending on whether a message and/or the manner in which the message was submitted complies with restrictions of the a key's use.