[Stealth] Derive stealth scan and spend keys from wallet key pool address

AmirAbrams · AmirAbrams · commit 7af905e8e6dd · 2019-05-02T14:35:31.000-05:00
diff --git a/src/key.cpp b/src/key.cpp
@@ -267,6 +267,17 @@ bool CKey::Derive(CKey& keyChild, ChainCode& ccChild, unsigned int nChild, const
     return ret;
 }
 
+bool CKey::DeriveChildKey(CKey& keyChild) const
+{
+    assert(IsValid());
+    assert(IsCompressed());
+    SecureVector newkeyData(32);
+    CSHA256().Write(&keydata[0], 32).Finalize(&newkeyData[0]);
+    keyChild.Set(newkeyData.begin(), newkeyData.end(), true);
+    keyChild.fCompressed = true;
+    return keyChild.fValid;
+}
+
 bool CExtKey::Derive(CExtKey& out, unsigned int _nChild) const
 {
     out.nDepth = nDepth + 1;
diff --git a/src/key.h b/src/key.h
@@ -150,6 +150,8 @@ class CKey
 
     //! Load private key and check that public key matches.
     bool Load(CPrivKey& privkey, CPubKey& vchPubKey, bool fSkipCheck);
+
+    bool DeriveChildKey(CKey& keyChild) const;
 };
 
 struct CExtKey {
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
@@ -163,25 +163,11 @@ static UniValue getnewstealthaddress(const JSONRPCRequest &request)
 
     LOCK2(cs_main, pwalletMain->cs_wallet);
 
-    // Get a new scan key from pool.
-    CPubKey scanPubKey;
-    if (!pwalletMain->GetKeyFromPool(scanPubKey, false))
+    CPubKey walletPubKey;
+    CStealthAddress sxAddr;
+    if (!pwalletMain->GetStealthAddressFromPool(walletPubKey, sxAddr, false))
         throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
-    CKeyID scanKeyID = scanPubKey.GetID();
-    CKey scanKey;
-    if (!pwalletMain->GetKey(scanKeyID, scanKey))
-        throw std::runtime_error(strprintf("%s -- Failed to get scan private key for stealth address\n", __func__));
-
-    // Get a new spend key from pool.
-    CPubKey spendPubKey;
-    if (!pwalletMain->GetKeyFromPool(spendPubKey, false))
-        throw JSONRPCError(RPC_WALLET_KEYPOOL_RAN_OUT, "Error: Keypool ran out, please call keypoolrefill first");
-    CKeyID spendKeyID = spendPubKey.GetID();
-    CKey spendKey;
-    if (!pwalletMain->GetKey(spendKeyID, spendKey))
-        throw std::runtime_error(strprintf("%s -- Failed to get spend private key for stealth address\n", __func__));
 
-    CStealthAddress sxAddr(scanKey, spendKey);
     if (!pwalletMain->AddStealthAddress(sxAddr))
         throw std::runtime_error(strprintf("%s -- Failed to write stealth address to local wallet.\n", __func__));
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
@@ -4473,6 +4473,29 @@ void CWallet::ReturnKey(int64_t nIndex, bool fInternal)
     LogPrintf("keypool return %d\n", nIndex);
 }
 
+bool CWallet::GetStealthAddressFromPool(CPubKey& pubkeyWallet, CStealthAddress& sxAddr, bool fInternal)
+{
+    if (IsLocked())
+        return false;
+
+    if (!GetKeyFromPool(pubkeyWallet, fInternal))
+        return false;
+
+    CKey walletKey, spendKey, scanKey;
+    if (!GetKey(pubkeyWallet.GetID(), walletKey))
+        return false;
+
+    if (!walletKey.DeriveChildKey(spendKey))
+        return false;
+
+    if (!spendKey.DeriveChildKey(scanKey))
+        return false;
+
+    CStealthAddress sx(scanKey, spendKey);
+    sxAddr = sx;
+    return true;
+}
+
 bool CWallet::GetKeyFromPool(CPubKey& result, bool fInternal)
 {
     int64_t nIndex = 0;
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
@@ -1233,6 +1233,7 @@ class CWallet : public CCryptoKeyStore, public CValidationInterface
     bool AddToStealthQueue(const std::pair<CKeyID, CStealthKeyQueueData>& pairStealthQueue);
     CWalletDB* GetWalletDB();
     bool HaveStealthAddress(const CKeyID& address) const;
+    bool GetStealthAddressFromPool(CPubKey& pubkeyWallet, CStealthAddress& sxAddr, bool fInternal);
 
 };
 
