How can I amend an Apk DEX file?
Steps
Decompile an original signed Apk file into archive file(including Smali DEX file, rescources, assets, lib etc)
Seperate the original DEX file apart from other original Apk files(resources, lib, assets etc)
Encrypt the original DEX file using AES method
Combine the original DEX file(already being encrypted in Step 3) with another DEX file sometimes called SHELL which has Decryption Function to decrypt the original DEX file when run in Dalvik virtual machine
Final step sign the Apk file again with release keystore to form a signed APK file and let users download
I am interested in learning the principle and skill to execute this process and how the Antivirus Database detect those content in the APK file