+/* --- Timing parameters --- */
+
+#define T_EXP MIN(60) /* Expiry time for a key */
+#define T_REGEN MIN(40) /* Regeneration time for a key */
+
+#define T_VALID SEC(20) /* Challenge validity period */
+#define T_RETRYMIN SEC(2) /* Minimum retry interval */
+#define T_RETRYMAX MIN(5) /* Maximum retry interval */
+#define T_RETRYGROW (5.0/4.0) /* Retry interval growth factor */
+
+#define T_WOBBLE (1.0/3.0) /* Relative timer randomness */
+