File-Based Encryption with SM4

Mobile phones have been developed from the general communication equipment to smart phones. People also use the phone from simply keeping in touch to storing more communication details and privacy. Nowadays, Android has became the most widely used operating system. Google proposed FDE (full disk encryption) in Android 5.0, 2014, and FBE (file-based encryption) in Android 7.0, 2016, to protect the user data from being stolen. This study introduces the the domestic encryption algorithm SM4, and through the AOSP (Android Open Source Project) to make it in Android kernel to achieve a rapid and complete "optional" file encryption to reflect the more humane way of operation.