From aba252206bf39ac81e6627354062c28fae05b0aa Mon Sep 17 00:00:00 2001
From: mtg0001 <106211915+mtg0001@users.noreply.github.com>
Date: Mon, 3 Aug 2026 15:11:55 -0300
Subject: Activate BIP44 wallet derivation (#124)

* Add BIP32 path derivation foundation

* Add HD wallet schema metadata

* Add provisional BIP44 coin type metadata

* Activate BIP44 wallet derivation

* wallet: scan BIP44 restore depth per branch

* wallet: widen default BIP44 restore lookahead

---------

Co-authored-by: Gilcimar Duarte <ti@gpm.infra>
---
 src/db.cpp | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

(limited to 'src/db.cpp')

diff --git a/src/db.cpp b/src/db.cpp
index 294920b..b7e7b91 100644
--- a/src/db.cpp
+++ b/src/db.cpp
@@ -554,6 +554,7 @@ bool CWalletDB::LoadWallet(vector<unsigned char>& vchDefaultKeyRet)
     // Whether wallet.dat actually carried a mining mode, as opposed to just the
     // ancient fGenerateBitcoins flag. See the reconciliation further down.
     bool fHaveStoredMineMode = false;
+    bool fHaveStoredHDCoinType = false;
     vchDefaultKeyRet.clear();
 
     // Satoshi's "todo: shouldn't we catch exceptions" sat here since 2009, and
@@ -651,6 +652,23 @@ bool CWalletDB::LoadWallet(vector<unsigned char>& vchDefaultKeyRet)
             {
                 ssValue >> nHDNext;
             }
+            else if (strType == "hdschema")
+            {
+                ssValue >> nHDKeySchema;
+            }
+            else if (strType == "hdcointype")
+            {
+                ssValue >> nHDCoinType;
+                fHaveStoredHDCoinType = true;
+            }
+            else if (strType == "hdreceivenext")
+            {
+                ssValue >> nHDReceiveNext;
+            }
+            else if (strType == "hdchangenext")
+            {
+                ssValue >> nHDChangeNext;
+            }
             else if (strType == "pool")
             {
                 int64 nIndex;
@@ -707,6 +725,38 @@ bool CWalletDB::LoadWallet(vector<unsigned char>& vchDefaultKeyRet)
         return false;
     }
 
+    if (HaveHDSeed())
+    {
+        if (nHDKeySchema == HD_SCHEMA_NONE)
+        {
+            nHDKeySchema = HD_SCHEMA_LEGACY;
+            printf("LoadWallet: deterministic seed has no schema metadata; "
+                   "treating it as legacy m/index'\n");
+        }
+        else if (nHDKeySchema != HD_SCHEMA_LEGACY &&
+                 nHDKeySchema != HD_SCHEMA_BIP44)
+        {
+            printf("LoadWallet: deterministic wallet schema %d (%s) is not "
+                   "supported by this build\n",
+                   nHDKeySchema, HDKeySchemaName(nHDKeySchema).c_str());
+            return false;
+        }
+        if (!fHaveStoredHDCoinType)
+        {
+            nHDCoinType = HD_BIP44_COIN_TYPE_BITFLASH_PROVISIONAL;
+            printf("LoadWallet: deterministic seed has no BIP44 coin type metadata; "
+                   "using provisional Bitflash coin type %u\n", nHDCoinType);
+        }
+    }
+    else
+    {
+        nHDKeySchema = HD_SCHEMA_NONE;
+        nHDNext = 0;
+        nHDReceiveNext = 0;
+        nHDChangeNext = 0;
+        nHDCoinType = HD_BIP44_COIN_TYPE_BITFLASH_PROVISIONAL;
+    }
+
     // fGenerateBitcoins and nMineMode only mean anything together, and a
     // wallet.dat can easily hold one without the other: Bitcoin 0.1.0 already
     // wrote fGenerateBitcoins when mining was toggled, years before this fork
-- 
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