Digital signatures described more clearly

easy/src/intro.typ

@@ -12,7 +12,8 @@ To be concrete, let's consider two examples of what protocols designed by classi
 
 - _Digital signatures_.
   RSA and ElGamal are examples of digital signature algorithms,
-  where Alice can perform some protocol to prove to Bob that she knows some secret numbers (for example, the discrete logarithm of some public value) that only she ought to know.
+  where Alice can perform some protocol to prove to Bob that she 
+  endorses a message.
   A more complicated example might be a
   #cite("https://en.wikipedia.org/wiki/Group_signature", "group signature scheme"),
   which allows one member of a group to sign a message on behalf of the group.