Sometimes we need to save a piece of data for the whole machine globally, not for a current user only. Unfortunately HKEY_LOCAL_MACHINE is write-protected for anybody except administrators. But you may create e.g. a key "a_key" below HKEY_LOCAL_MACHINE with admin rights and then - assign "write-everybody" permission to "a_key", so unprivileged users will share the same data and will be allowed to modify it. The following function _RegSetKeySecuritySetNullDacl sets "write-everybody" permission