@Override
    public String generate(final Principal principal, final String service) {
        val attributes = principal.getAttributes();
        LOGGER.debug("Found principal attributes [{}] to use when generating persistent identifiers", attributes);
        val principalId = determinePrincipalIdFromAttributes(principal.getId(), attributes);
        return generate(principalId, service);
    }
Prepare message digest message digest.

@param principal the principal
@param service   the service
@return the message digest
core/cas-server-core-services-api/src/main/java/org/apereo/cas/authentication/principal/ShibbolethCompatiblePersistentIdGenerator.java