+/* How many times to read the TSC as a randomness source. */
+# define TSC_READ_COUNT 4
+
+/* Maximum reseed intervals */
+# define MAX_RESEED_INTERVAL (1 << 24)
+# define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
+
+/* Default reseed intervals */
+# define MASTER_RESEED_INTERVAL (1 << 8)
+# define SLAVE_RESEED_INTERVAL (1 << 16)
+# define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
+# define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
+
+
+
+/*
+ * Maximum input size for the DRBG (entropy, nonce, personalization string)
+ *
+ * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
+ *
+ * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
+ */
+# define DRBG_MAX_LENGTH INT32_MAX
+
+
+
+/*
+ * Maximum allocation size for RANDOM_POOL buffers
+ *
+ * The max_len value for the buffer provided to the rand_drbg_get_entropy()
+ * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
+ * is used. Since this is much too large to be allocated, the rand_pool_new()
+ * function chooses more modest values as default pool length, bounded
+ * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
+ *
+ * The choice of the RAND_POOL_FACTOR is large enough such that the
+ * RAND_POOL can store a random input which has a lousy entropy rate of
+ * 8/256 (= 0.03125) bits per byte. This input will be sent through the
+ * derivation function which 'compresses' the low quality input into a
+ * high quality output.
+ *
+ * The factor 1.5 below is the pessimistic estimate for the extra amount
+ * of entropy required when no get_nonce() callback is defined.
+ */
+# define RAND_POOL_FACTOR 256
+# define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
+ 3 * (RAND_DRBG_STRENGTH / 16))
+/*
+ * = (RAND_POOL_FACTOR * \
+ * 1.5 * (RAND_DRBG_STRENGTH / 8))
+ */