diff --git a/doxygen/input/doc_rng.h b/doxygen/input/doc_rng.h
index 252ee1e..40852ee 100644
--- a/doxygen/input/doc_rng.h
+++ b/doxygen/input/doc_rng.h
@@ -7,7 +7,14 @@
  * @addtogroup rng_module Random number generator (RNG) module
  * 
  * The Random number generator (RNG) module provides random number
- * generation, see \c havege_rand(). It uses the HAVEGE (HArdware Volatile 
+ * generation, see \c ctr_dbrg_random() or \c havege_random().
+ *
+ * The former uses the block-cipher counter-mode based deterministic random
+ * bit generator (CTR_DBRG) as specified in NIST SP800-90. It needs an external
+ * source of entropy. For these purposes \c entropy_func() can be used. This is
+ * an implementation based on a simple entropy accumulator design.
+ *
+ * The latter random number generator uses the HAVEGE (HArdware Volatile
  * Entropy Gathering and Expansion) software heuristic which is claimed 
  * to be an unpredictable or empirically strong* random number generation.
  *