[glib] GHash: add note about randomness in hashing

[Ryan Lortie <ryanl src gnome org>]

commit 12060df9f17a48cd4c7fda27a0af70c17c308ad9
Author: Ryan Lortie <desrt desrt ca>
Date:   Wed Jan 25 10:09:09 2012 -0500

    GHash: add note about randomness in hashing
    
    To clarify our statements about being robust against outside attackers
    degrading the performance of your hashtable.

 glib/ghash.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/glib/ghash.c b/glib/ghash.c
index 92c16c9..b058d17 100644
--- a/glib/ghash.c
+++ b/glib/ghash.c
@@ -165,6 +165,11 @@
  * Using g_str_hash() in that situation might make your application
  * vulerable to <ulink url="https://lwn.net/Articles/474912/";>Algorithmic Complexity Attacks</ulink>.
  *
+ * The key to choosing a good hash is unpredictability.  Even
+ * cryptographic hashes are very easy to find collisions for when the
+ * remainder is taken modulo a somewhat predictable prime number.  There
+ * must be an element of randomness that an attacker is unable to guess.
+ *
  * Returns: the hash value corresponding to the key
  */