Merge remote-tracking branch 'origin/pr/2192' into development

* origin/pr/2192:
  Increase okm_hex buffer to contain null character
  Minor modifications to hkdf test
  Add explanation for okm_string size
  Update ChangeLog
  Reduce buffer size of okm
  Reduce Stack usage of hkdf test function
diff --git a/ChangeLog b/ChangeLog
index 9ed7b4c..e1588f5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,7 @@
      Christian Walther in #2239.
    * Fix potential memory leak in X.509 self test. Found and fixed by
      Junhwan Park, #2106.
+   * Reduce stack usage of hkdf tests. Fixes #2195.
 
 Changes
    * Server's RSA certificate in certs.c was SHA-1 signed. In the default