standardized symbols via "isabelle update_sub_sup", excluding src/Pure and src/Tools/WWW_Find;
theory All_Symmetric
imports Message
begin
text {* All keys are symmetric *}
defs all_symmetric_def: "all_symmetric \<equiv> True"
lemma isSym_keys: "K \<in> symKeys"
by (simp add: symKeys_def all_symmetric_def invKey_symmetric)
end