clarify comment

diff --git a/crypto/rand/md_rand.c b/crypto/rand/md_rand.c
index 88088ce73c3c2629753932e1fc2aa2ee2bbd06c6..b2f04ff13ec9a4a4c5ca17ff17b7fe016efd16f6 100644 (file)
--- a/crypto/rand/md_rand.c
+++ b/crypto/rand/md_rand.c
@@ -476,11 +476,14 @@ static int ssleay_rand_bytes(unsigned char *buf, int num)
                MD_Update(&m,(unsigned char *)&(md_c[0]),sizeof(md_c));
 
 #ifndef PURIFY /* purify complains */
-               /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
+               /* The following line uses the supplied buffer as a small
+                * source of entropy: since this buffer is often uninitialised
+                * it may cause programs such as purify or valgrind to
+                * complain. So for those builds it is not used: the removal
+                * of such a small source of entropy has negligible impact on
+                * security.
+                */
                MD_Update(&m,buf,j);
-               /* We know that line may cause programs such as
-                  purify and valgrind to complain about use of
-                  uninitialized data.  */
 #endif
 
                k=(st_idx+MD_DIGEST_LENGTH/2)-st_num;