About Nokia 5320 SMS encryption.

I also use 5320. The machine itself cannot be encrypted!

NetQin Communication Manager (free) has a private message. If you want to lock one or several people's short messages, you can set the password directly in the software. If you want to delete it, please make corresponding settings in the software. Similar software includes 360 mobile phone security guard (completely free), Kabbah 8.0 mobile phone version (free for one month), and some software. You can go to Skynet Software (a mobile phone software download website) to download these softwares, all of which are free.

It is recommended to download 360 mobile phone security guards, or you can download them directly from your computer.

As long as you set a contact's privacy level in the software, all his (her) short messages will be stored in the software, which can't be seen by turning on the phone directly. When you delete or remove the password settings, the SMS will be returned to your mobile phone, so don't worry about losing it!