[Wallet] extend CKeyMetadata with HD keypath

src/wallet/wallet.cpp

@@ -126,6 +126,8 @@ CPubKey CWallet::GenerateNewKey()
             // childIndex | BIP32_HARDENED_KEY_LIMIT = derive childIndex in hardened child-index-range
             // example: 1 | BIP32_HARDENED_KEY_LIMIT == 0x80000001 == 2147483649
             externalChainChildKey.Derive(childKey, hdChain.nExternalChainCounter | BIP32_HARDENED_KEY_LIMIT);
+            metadata.hdKeypath     = "m/0'/0'/"+std::to_string(hdChain.nExternalChainCounter)+"'";
+            metadata.hdMasterKeyID = hdChain.masterKeyID;
             // increment childkey index
             hdChain.nExternalChainCounter++;
         } while(HaveKey(childKey.key.GetPubKey().GetID()));

src/wallet/walletdb.h

@@ -73,9 +73,13 @@ public:
 class CKeyMetadata
 {
 public:
-    static const int CURRENT_VERSION=1;
+    static const int VERSION_BASIC=1;
+    static const int VERSION_WITH_HDDATA=10;
+    static const int CURRENT_VERSION=VERSION_WITH_HDDATA;
     int nVersion;
     int64_t nCreateTime; // 0 means unknown
+    std::string hdKeypath; //optional HD/bip32 keypath
+    CKeyID hdMasterKeyID; //id of the hd masterkey used to derive this key
 
     CKeyMetadata()
     {
@@ -85,6 +89,7 @@ public:
     {
         nVersion = CKeyMetadata::CURRENT_VERSION;
         nCreateTime = nCreateTime_;
+        hdKeypath.clear();
     }
 
     ADD_SERIALIZE_METHODS;
@@ -94,12 +99,18 @@ public:
         READWRITE(this->nVersion);
         nVersion = this->nVersion;
         READWRITE(nCreateTime);
+        if (this->nVersion >= VERSION_WITH_HDDATA)
+        {
+            READWRITE(hdKeypath);
+            READWRITE(hdMasterKeyID);
+        }
     }
 
     void SetNull()
     {
         nVersion = CKeyMetadata::CURRENT_VERSION;
         nCreateTime = 0;
+        hdKeypath.clear();
     }
 };