its poor form to log private data

plugins/producer_plugin/producer_plugin.cpp

@@ -504,7 +504,8 @@ void producer_plugin::plugin_initialize(const boost::program_options::variables_
          try {
             auto key_id_to_wif_pair = dejsonify<std::pair<public_key_type, private_key_type>>(key_id_to_wif_pair_string);
             my->_signature_providers[key_id_to_wif_pair.first] = make_key_signature_provider(key_id_to_wif_pair.second);
-            wlog("\"private-key\" is DEPRECATED, use \"signature-provider=${pub}=KEY:${priv}\"", ("pub",key_id_to_wif_pair.first)("priv", key_id_to_wif_pair.second));
+            auto blanked_privkey = std::string(std::string(key_id_to_wif_pair.second).size(), '*' );
+            wlog("\"private-key\" is DEPRECATED, use \"signature-provider=${pub}=KEY:${priv}\"", ("pub",key_id_to_wif_pair.first)("priv", blanked_privkey));
          } catch ( fc::exception& e ) {
             elog("Malformed private key pair");
          }