private static JWSAlgorithm determineSigningAlgorithm(final RegisteredService registeredService) {
        val serviceSigningAlg = getRegisteredServiceJwtProperty(registeredService, RegisteredServiceProperties.TOKEN_SECRET_SIGNING_ALG);
        val signingSecretAlg = StringUtils.defaultIfBlank(serviceSigningAlg, JWSAlgorithm.HS256.getName());
        val sets = new HashSet<Algorithm>();
        sets.addAll(JWSAlgorithm.Family.EC);
        sets.addAll(JWSAlgorithm.Family.HMAC_SHA);
        sets.addAll(JWSAlgorithm.Family.RSA);
        sets.addAll(JWSAlgorithm.Family.SIGNATURE);
        return findAlgorithmFamily(sets, signingSecretAlg, JWSAlgorithm.class);
    }
Create a JWT authenticator.

@return the jwt authenticator
support/cas-server-support-token-authentication/src/main/java/org/apereo/cas/token/authentication/TokenAuthenticationSecurity.java