[Wallet] Add simplest BIP32/deterministic key generation implementation

src/wallet/wallet.cpp

@@ -94,7 +94,48 @@ CPubKey CWallet::GenerateNewKey()
     bool fCompressed = CanSupportFeature(FEATURE_COMPRPUBKEY); // default to compressed public keys if we want 0.6.0 wallets
 
     CKey secret;
-    secret.MakeNewKey(fCompressed);
+
+    // Create new metadata
+       int64_t nCreationTime = GetTime();
+       CKeyMetadata metadata(nCreationTime);
+
+       // use HD key derivation if HD was enabled during wallet creation
+       if (!hdChain.masterKeyID.IsNull()) {
+           // for now we use a fixed keypath scheme of m/0'/0'/k
+           CKey key;                      //master key seed (256bit)
+           CExtKey masterKey;             //hd master key
+           CExtKey accountKey;            //key at m/0'
+           CExtKey externalChainChildKey; //key at m/0'/0'
+           CExtKey childKey;              //key at m/0'/0'/<n>'
+
+           // try to get the master key
+           if (!GetKey(hdChain.masterKeyID, key))
+               throw std::runtime_error("CWallet::GenerateNewKey(): Master key not found");
+
+           masterKey.SetMaster(key.begin(), key.size());
+
+           // derive m/0'
+           // use hardened derivation (child keys > 0x80000000 are hardened after bip32)
+           masterKey.Derive(accountKey, 0 | 0x80000000);
+
+           // derive m/0'/0'
+           accountKey.Derive(externalChainChildKey, 0 | 0x80000000);
+
+           // derive child key at next index, skip keys already known to the wallet
+           do
+           {
+               externalChainChildKey.Derive(childKey, hdChain.nExternalChainCounter | 0x80000000);
+               // increment childkey index
+               hdChain.nExternalChainCounter++;
+           } while(HaveKey(childKey.key.GetPubKey().GetID()));
+           secret = childKey.key;
+
+           // update the chain model in the database
+           if (!CWalletDB(strWalletFile).WriteHDChain(hdChain))
+               throw std::runtime_error("CWallet::GenerateNewKey(): Writing HD chain model failed");
+    } else {
+            secret.MakeNewKey(fCompressed);
+    }
 
     // Compressed public keys were introduced in version 0.6.0
     if (fCompressed)
@@ -104,8 +145,7 @@ CPubKey CWallet::GenerateNewKey()
     assert(secret.VerifyPubKey(pubkey));
 
     // Create new metadata
-    int64_t nCreationTime = GetTime();
-    mapKeyMetadata[pubkey.GetID()] = CKeyMetadata(nCreationTime);
+    mapKeyMetadata[pubkey.GetID()] = metadata;
     if (!nTimeFirstKey || nCreationTime < nTimeFirstKey)
         nTimeFirstKey = nCreationTime;
 
@@ -1333,6 +1373,37 @@ CAmount CWallet::GetChange(const CTxOut& txout) const
     return (IsChange(txout) ? txout.nValue : 0);
 }
 
+bool CWallet::SetHDMasterKey(const CKey& key)
+{
+    LOCK(cs_wallet);
+
+    // store the key as normal "key"/"ckey" object
+    // in the database
+    // key metadata is not required
+    CPubKey pubkey = key.GetPubKey();
+    if (!AddKeyPubKey(key, pubkey))
+        throw std::runtime_error("CWallet::GenerateNewKey(): AddKey failed");
+
+    // store the keyid (hash160) together with
+    // the child index counter in the database
+    // as a hdchain object
+    CHDChain newHdChain;
+    newHdChain.masterKeyID = pubkey.GetID();
+    SetHDChain(newHdChain, false);
+
+    return true;
+}
+
+bool CWallet::SetHDChain(const CHDChain& chain, bool memonly)
+{
+    LOCK(cs_wallet);
+    if (!memonly && !CWalletDB(strWalletFile).WriteHDChain(chain))
+        throw runtime_error("AddHDChain(): writing chain failed");
+
+    hdChain = chain;
+    return true;
+}
+
 bool CWallet::IsMine(const CTransaction& tx) const
 {
     BOOST_FOREACH(const CTxOut& txout, tx.vout)