Implement viewing key storage in the wallet

src/wallet/wallet.cpp

@@ -107,6 +107,10 @@ bool CWallet::AddZKey(const libzcash::SpendingKey &key)
     if (!CCryptoKeyStore::AddSpendingKey(key))
         return false;
 
+    // check if we need to remove from viewing keys
+    if (HaveViewingKey(addr))
+        RemoveViewingKey(key.viewing_key());
+
     if (!fFileBacked)
         return true;
 
@@ -246,6 +250,33 @@ bool CWallet::LoadZKey(const libzcash::SpendingKey &key)
     return CCryptoKeyStore::AddSpendingKey(key);
 }
 
+bool CWallet::AddViewingKey(const libzcash::ViewingKey &vk)
+{
+    if (!CCryptoKeyStore::AddViewingKey(vk))
+        return false;
+    nTimeFirstKey = 1; // No birthday information for viewing keys.
+    if (!fFileBacked)
+        return true;
+    return CWalletDB(strWalletFile).WriteViewingKey(vk);
+}
+
+bool CWallet::RemoveViewingKey(const libzcash::ViewingKey &vk)
+{
+    AssertLockHeld(cs_wallet);
+    if (!CCryptoKeyStore::RemoveViewingKey(vk))
+        return false;
+    if (fFileBacked)
+        if (!CWalletDB(strWalletFile).EraseViewingKey(vk))
+            return false;
+
+    return true;
+}
+
+bool CWallet::LoadViewingKey(const libzcash::ViewingKey &vk)
+{
+    return CCryptoKeyStore::AddViewingKey(vk);
+}
+
 bool CWallet::AddCScript(const CScript& redeemScript)
 {
     if (!CCryptoKeyStore::AddCScript(redeemScript))