It's very much important to keep your personal data secure and within your control. If someone access to some of our most important secrets like sensitive business emails, financial details, contact information, and even your honeymoon photos what will you do? Prevention is better than cure.
Security software vendor Avast had done a study about this. The findings are horrifying, they purchased 20 used Android smartphones on eBay and only using readily available data recovery software to get recover more than 40,000 photos, 750 emails and text messages, and 250 contacts, along with the identities of four of the previous device owners. This suggested that the default data wipe tool in Android may not be enough to permanently delete personal data from your old device.
Why this happens?
When we do a factory reset we think that all the data in it is wiped off. But it only deletes the addresses of all of the data, so the device no longer knows where the data is stored. But actually the data is residing in the memory. So, using some recovery tool someone can recover it. The security software vendors in the market like Avast offer data deletion tools. You can also use these simple steps to erase data from your old device.
Step I: Encrypt your data
To encrypt your device on stock Android, enter settings, click on Security, and select Encrypt phone. If it is not there search your phone’s menu you will find an encryption option. It requires you to put a PIN or password in every time you turn on the phone. https://smartgad4u.blogspot.com/2018/09/is-galaxy-note-9-is-better-than-iphone.html If you encrypt your data, even if the wipe doesn't fully delete the data there is no problem. If some retrieve the data they need a special key decrypt it. So, they cannot read it. Note: Charge your phone fully or keep it plugged in to the charger while decrypting. It may take too much time.
Wipe all the data using the Factory data reset.
Settings >> Backup & reset option >> Factory data reset.
Step III: Overwrite with junk data
Actually you are safe now, if you want more protection from data recovery. Do this; load your device with fake photos, contacts, and other files. There are some apps are available in the Play Store for this purpose like .Actually following steps one and two should be enough. Without the PIN you had entered during the encryption nobody can decrypt you data.