When I prepare for travel, I take some steps to make sure that my protected data will not be read or otherwise mishandled by customs. I then follow-up with rigorous steps to ensure that my information and devices maintain their integrity and that I can trust them with the same degree that I did before travel. (For cell phones, basically not at all.) This article covers the broad strokes, and I will write a detailed guide sometime in the near future.<\/p>\n
This is done by connecting the phone to my PC, and creating a VeraCrypt container of the appropriate size. I then move all of the data from my phone to the PC.<\/p>\n
Wipe: Reinstall OS and Overwrite All Free Space with Garbage Data<\/p>\n
You can use the \u201csystem restore\u201d or \u201cfactory reset\u201d feature on a lot of phones in order to roll back all of your apps, settings, and caches to the factory defaults. If you\u2019ve installed a privacy build of Android like LineageOS, you can wipe the device with something like TWRP and reinstall the OS itself for the highest level of assurance.<\/p>\n
You then want to overwrite all of the free space on the device with garbage data. This is to prevent files from being recovered from flash memory. When you delete data off of your Android phone, the file is deleted from the index, but the file itself still exists until it is overwritten by new data. Once you fill the phone with garbage data, it is safe to delete it all and use the free space normally.<\/p>\n
Do be aware that some files will still remain after this process due to wear-leveling. It is extremely hard to verify that any flash-based storage is truly fully erased because of this. Expect that some phone files remain no matter what you do. This is less of a concern if you\u2019ve enabled full-disk encryption in Android, because the data will be encrypted and the keys to that encryption will be thrown away when you reinstall the OS and set up a new instance of full disk encryption.<\/p>\n
The first thing I do is enable full disk encryption, this makes the device much harder to tamper with or otherwise read. I restore my contacts, install Lyft, install Signal Messenger, install Firefox Mobile, and reset two factor authentication for the relevant devices.<\/p>\n
I then place a VeraCrypt container on the phone that contains the information needed to restore the device if it is wiped again. Things like passwords, QR codes for 2fa activation, contacts, etc. This same data is cloned to the notebook PC that I bring along. This makes it so the devices can be wiped while I am traveling.<\/p>\n