底线：如何安全是 UN 加密设备上的数据/密码？
My phone is currently inoperative. Samsung asked me to drop it at an approved repair center, which will handle shipment and reception to/from Samsung.
Being unable to boot my phone, it was impossible for me to remove personal files from it.
I am aware all my files will be accessible to anyone handling my phone, once repaired. But what about my passwords ? I know it's possible to get saved WiFi passwords with root access. Is it possible too for passwords from applications ? (Gmail, Dropbox, Website passwords from Chrome, ...)
Bottom line: How safe are my data/passwords on an unencrypted device ?
As The Andro Nerd pointed out in his answer, most apps store passwords (and other sensitive information) encrypted. Some even don't store them at all (they use a kind of "tokens", as is available with most Google apps -- or they don't store anything like that).
Unfortunately, only most apps seem to care this way. Some store everything plain text (the stock email app on some HTC devices is known for that, for example: Storing passwords and even directory information plain text for Exchange services. Sources for this allegation can be found in the book mentioned below).
It's hard to really know which apps are save, though some services help you figure it out -- see e.g. ViaForensic's AppWatchdog, where they thoroughly investigate apps for things like that (but with limited ressources are far from covering everything). Some security blogs inform about found issues as well -- and if some well-known app is affected by such a security hole (as e.g. mentioned email app, or Skype), all the blogs in the world will spread word.
Knowing the structures how data are saved, you could investigate yourself (if your device is rooted, that is). Andrew Hoog's book Android Forensics and Mobile Security is one good source teaching you how to do that:
Apps store their data below the
/data/data, in a directory with the apps package name as name (for skype, this would be
/data/data/com.skype.merlin_mecha/). By default, that directory is accessible by the app alone (and, of course, by root) -- which is why it requires root privileges to dig deeper. The basic structure below is as follows:
/data/data/com.example.demoapp xe2x94x9cxe2x94x80xe2x94x80 cache Directory xe2x94x82 xe2x94x94xe2x94x80xe2x94x80 webviewCache Directory xe2x94x82 xe2x94x9cxe2x94x80xe2x94x80 027e59a0 Cache file xe2x94x82 xe2x94x94xe2x94x80xe2x94x80 057606c4 Cache file xe2x94x9cxe2x94x80xe2x94x80 databases Directory xe2x94x82 xe2x94x94xe2x94x80xe2x94x80 example.db SQLite database xe2x94x9cxe2x94x80xe2x94x80 lib Directory xe2x94x94xe2x94x80xe2x94x80 shared_prefs Directory xe2x94x94xe2x94x80xe2x94x80 example.xml Config file
Obviously, there are two major places to check:
shared_prefsdirectory, containing XML files. As those are plain-text, they should be easy to investigate.
databasesdirectory. Database files are usually in the SQLite standard, so you can investigate them with either an SQLite command line client, or with a graphical frontend like SQLiteMan.
A thorough information on this topic would go too far here -- but you got the idea, I hope.
I wouldn't be that much concerned with Samsungs official service (though "bad guys" could sit everywhere -- but one should not go paranoid about it. But of course it is a generally good idea to be careful of which apps one uses. Too late for your current case, might be -- but there's always a tomorrow.
Most (if not all) applications will store saved passwords in an encrypted format in their database in their data folder.
As such, your passwords will be safe - they would have to access the database, and then decrypt the stored the encrypted password.
As well as that, they will most likely wipe your device anyway (not always done, depends on the repair).