Preparing android device with root for sale. How to fill the disk with zeros?

Question

linux

Good afternoon.
An android phone is available, rooted , CyanogenMod firmware . There are a couple of photos and files on the phone, which should not be shared with third parties. ( Passwords to many sites, pin codes of salary cards, access to the company's servers, and much more. ) I'm going to sell the phone, I read on Habré that resetting to factory settings has no effect, files can be easily restored. Question - how to fill the disk with zeros using dd (linux console utility)? The problem is that the phone connects via mtp , and it is not visible in /dev/sdX . Or are there other options? UPD:



And there are no console utilities for cleaning?

Answer 1

And if you turn on full data encryption with some long password?

Answer 2

There, it’s not just necessary to score with zeros, but to do it dofig times (from 5 to 54) - there are even standards for this.
Look at the special programs - they can.

Answer 3

There is another time-consuming option: delete all personal information in the usual way, untie all accounts, change passwords and pin codes.

Answer 4

reset to zn. download movies / music to the eyeballs through the cable.
repeat 2-3 times

Answer 5

Some service flashers have NAND Erase.
But most likely after that you will have to flash the phone via JTAG.
The best option is to fill the / data section with a random one, format it in EXT4 and call Trim. All through recovery (TWRP). Utilities dd, mke2fs, fstrim.