account: add a forget_spend_key method

src/cryptonote_core/account.cpp

@@ -59,6 +59,11 @@ DISABLE_VS_WARNINGS(4244 4345)
     m_keys = account_keys();
   }
   //-----------------------------------------------------------------
+  void account_base::forget_spend_key()
+  {
+    m_keys.m_spend_secret_key = crypto::secret_key();
+  }
+  //-----------------------------------------------------------------
   crypto::secret_key account_base::generate(const crypto::secret_key& recovery_key, bool recover, bool two_random)
   {
     crypto::secret_key first = generate_keys(m_keys.m_account_address.m_spend_public_key, m_keys.m_spend_secret_key, recovery_key, recover);

src/cryptonote_core/account.h

@@ -67,6 +67,8 @@ namespace cryptonote
     bool load(const std::string& file_path);
     bool store(const std::string& file_path);
 
+    void forget_spend_key();
+
     template <class t_archive>
     inline void serialize(t_archive &a, const unsigned int /*ver*/)
     {