Add mo beef

hip-0304.md

@@ -21,6 +21,9 @@ This is an xxx HIP describing signed Sapling messages.
 # Motivation
 
 TLDR: Extend the `signmessage` and `verifymessage` RPCs to Sapling shielded addresses.
+Many people, including the author, have created Github issues asking for the ability to
+sign messages with zaddrs. Originally, it was not possible with Sprout addresses but 
+now Sapling zaddrs have the internal machinery to support this use case.
 
 # Specification
 
@@ -34,6 +37,17 @@ which are direct shielded counterparts to the original Bitcoin RPCs:
     signmessage
     verifymessage
 
+This specification is directly influenced by various Zcash Github issues and ZIP304
+such as https://github.com/zcash/zcash/issues/3159 and https://github.com/zcash/zcash/issues/1770
+and the algorithm designed by Daira and other Zcash developers. We simply took the publicly
+defined algorithm and decided to actually implement it and decide any implementation details that
+would be needed along the way.
+
+## Internal Design
+
+One option would be to write a custom zk-SNARK "circuit" to support signing via a zaddr. This would
+be a large amount of work and was dismissed, reasonably, as not viable by Zcash developers.
+
 
 # References