Additional clean-up considerations
A FACTORY RESET IS ALL WELL AND GOOD, BUT WITH THE RIGHT SOFTWARE, THERE IS A POSSIBILITY THAT SOME DATA CAN STILL BE RECOVERED. HERE’S WHAT YOU NEED TO BE WARY OF.
“SSDs should be more secure (once properly erased), but in practice, many models do not fully overwrite data when they should.”
Even after a format or wipe, specialist software can wind back the process and sniff out intact information. Mechanical HDDs are theoretically more vulnerable; with information recoverable even after it has been overwritten. SSDs should be more secure (once properly erased) ,but in practice, many models do not fully overwrite data when they should. While a device might seem fully and securely erased, some missed data could be lurking. Fortunately, there is a range of tools and utilities available that help make data very hard to recover.
ENCRYPTION
No matter what process or software is used, there is the (slightest) potential for information to remain. The best option for the security conscious is to first encrypt your entire device, then perform the factory reset or other secure erase. This means that, even if there is a problem and any data can be recovered, it will still be encrypted and extremely hard to crack. While not strictly necessary, for most devices, it’s an easy way to make sure your personal data (almost) definitely can’t be recovered.
ANDROID
Unless you have an ancient device, it should support encryption. On newer models, it’s enabled by default, but on older models, it has to be turned on manually. Before encrypting, you need 80%+ battery, and the phone charging. Open up ‘Settings > Security’ (or on some phones, Storage), then select ‘Encrypt phone’. Depending on the version of Android in use, the exact location and wording can vary. After encrypting, an app such as SDelete — File Shredder ( goo.gl/MiebhP) can be used to overwrite your devices storage to render personal information much harder to recover. The wipe can take an hour or two, after which, a factory reset will complete the process.
IOS
Unless you have a particularly old device, your Apple iPhone, iPod or iPad is already encrypted when you create a lock screen passcode. Performing a factory reset removes the ability to decrypt that data (at least in any reasonable way), so any personal data should remain secure. As such, Apple has actually removed ‘Secure Erase’ style software from the app store as ‘misleading’ and unnecessary. One low-tech option to at least overwrite some of the data storage (after a reset) is to record a long video until the phone is totally full, then delete it.
WINDOWS PHONE
In the latest Windows 10 Mobile, encryption is not enabled by default — head to ‘Settings > Device Encryption’ and turn the slider to ‘On’. After encrypting the device, a factory reset will render any data unrecoverable. With Windows Phone 8 or 8.1, it’s not so simple. The OS supports encryption, but it can’t be simply turned on. The phone must be managed by an external policy that activates the encryption. While possible to do, it’s beyond the scope here.