From bc68788317a4ece16f0cfb0cb7eb1e0e220cbc6f Mon Sep 17 00:00:00 2001
From: phantomcircuit <phantomcircuit@debian>
Date: Sat, 12 Oct 2013 23:44:28 -0700
Subject: [PATCH] comment explaining new wallet format for key/wkey entries

---
 src/walletdb.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/walletdb.cpp b/src/walletdb.cpp
index f7edd084..d31db5e4 100644
--- a/src/walletdb.cpp
+++ b/src/walletdb.cpp
@@ -317,6 +317,12 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
                 ssValue >> wkey;
                 pkey = wkey.vchPrivKey;
             }
+            
+            // Old wallets store keys as "key" [pubkey] => [privkey]
+            // ... which was slow for wallets with lots of keys, because the public key is re-derived from the private key
+            // using EC operations as a checksum.
+            // Newer wallets store keys as "key"[pubkey] => [privkey][hash(pubkey,privkey)], which is much faster while
+            // remaining backwards-compatible.
             try
             {
                 ssValue >> hash;