wallet: derive the key pool from a seed, so a phrase could bring it back (#93)

Adds BIP32 derivation behind the wallet key pool, with no user-facing way to create a seed yet. wallet.dat gains hdmaster/hdchaincode/hdnext; the mnemonic is never stored. TopUpKeyPool derives m/n' when a seed exists and falls back to a random key, with a log line, if derivation fails. New -selftest=wallet-hd, wired into make tests on both platforms.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/db.cpp b/src/db.cpp
index d482c5a..294920b 100644
--- a/src/db.cpp
+++ b/src/db.cpp
@@ -639,6 +639,18 @@ bool CWalletDB::LoadWallet(vector<unsigned char>& vchDefaultKeyRet)
             {
                 ssValue >> vchDefaultKeyRet;
             }
+            else if (strType == "hdmaster")
+            {
+                ssValue >> vchHDMaster;
+            }
+            else if (strType == "hdchaincode")
+            {
+                ssValue >> vchHDChainCode;
+            }
+            else if (strType == "hdnext")
+            {
+                ssValue >> nHDNext;
+            }
             else if (strType == "pool")
             {
                 int64 nIndex;