1 files changed, 3 insertions, 0 deletions
diff --git a/TODO b/TODO
index 6f7903dd..b1963354 100644
--- a/TODO
+++ b/TODO
@@ -25,3 +25,6 @@
   the asymmetric ciphers could be changed for convenient interaction
   with the ac interface (i.e. by using ac's `data sets') and the pk
   interface could be changed to be a wrapper for the ac interface.
+
+* HMAC won't work with sha-512 due to the different block size.  OTOH,
+  I can imagine no cryptographic reason to use it.