update

README.md

@@ -4,11 +4,11 @@ A walled citadel on a hill for your shielded funds.
 
 ## What is Byrsa?
 
-Byrsa is a new set of consensus rules for using shielded funds, which does
-not modify the internals of the Zcash Protocol, but sits on top
-of it. It defines certain wallet and transction conditions that
-must be upheld for transactions to be accepted by the network.
-These conditions
+Byrsa is a new set of RPC functionality and consensus rules for
+using shielded funds, which do not currently modify the internals of the
+Zcash Protocol, but sit on top of it. It defines certain wallet
+and transction conditions that must be upheld for transactions
+to be accepted by the network.
 
 ## How is Byrsa implemented?
 
@@ -20,15 +20,44 @@ making transactions.
 
 From the perspective of the average GUI wallet user, It Just Works.
 There are no additional mandatory steps for the user when sending
-each transaction.
+each transaction. There will be some options for advanced users, to
+tweak the settings, but using them is not required for increased privacy.
+They will mostly serve as ways for developers to experiment and optimize
+things.
 
 ## What are the goals of Byrsa?
 
  * Make linkability analysis of zaddrs drastically more expensive
  * Allow people to make zaddr xtns safely/privately without thinking about
    metadata leakage or advanced techniques
- * Prevent some blockchain operations which give out too much metadata
+ * Prevent average users from making some blockchain operations which give out too much metadata
  * Break some assumptions which many blockchain analyst software uses
  * Require blockchain analysts to write new software
  * Increase the privacy of all funds in the shielded pool
+ * Introduce non-determinism to prevent ITM/Metaverse style metadata attacks
+
+## What are the limitations/downsides of Byrsa?
+
+The goal of Byrsa is increased privacy and the cost is increased blockspace usage per transaction,
+increased CPU time and RAM to validate transcations and as a secondary effect, increased sync times.
+
+Byrsa potentially adds inputs and outputs to transactions to increase their privacy,
+and so the maximum number of actual recipients is lower when Byrsa is enabled. In practice,
+transactions can still send to over 1000 recipients even with Byrsa protections, so it
+doesn't actually effect any current users, as far as we know.
+
+How much longer will average xtn take?
+More RAM? No!
+
+
+## Implementation Details
+
+These RPCs are modified:
+
+```
+	z_sendmany
+	z_shieldcoinbase
+	z_mergetoaddress
+```
+