[Q] Nexus S Stock ICS "Encrypt Phone" details? - Nexus S Q&A, Help & Troubleshooting

Hi all,
So I've got a new Nexus S, and I'm running the stock 4.0.3 from Google. This phone hasn't yet been rooted or had the bootloader unlocked.
I'm a big security fan, and I've read about how tools exist that can simply slurp all the data off a phone without even breaking a sweat, and I'd like to be able to defeat such abilities. Ideally, I'd even like to be able to have su access to a device as the authorized user and owner (This is a Wind Mobile Canada phone, the carrier has no stake in it at all). I remember hacking away at my T-Mobile G1, and being a little concerned that merely pressing a button to get into the recovery at boot-time would enable full access to everything on the device for a knowledgeable attacker.
So I see under "Settings - Security" there's an "Encrypt Phone" option. Google has documentation here for the Galaxy Nexus, but it lacks specifics.
Can anyone here provide or point me to proper details? What is encrypted, how is it encrypted, how strong is the encryption, how much impact does this have on performance and battery life?
*edit - I just found this. If I'm reading this right, this is FDE on the /data partition, which is very good. Still doesn't do anything for the sdcard/usb partition though.

Have you tried it? On my Nexus S 4g (which is, I grant you, slightly different) it DOES encrypt the sdcard as well. I'm interested in other's experiences with FDE. Particularly weaknesses and developing procedures for restoring/flashing after enabling FDE.

Hi,
As part of setting up a work email account, I had to encrypt my Nexus S including the SD card. Unfortunately, that meant that I could not access the SD card to transfer music, photos...or most importantly, new ROMs to flash. I did a factory reset, which seemed to be the only option to get rid of it.
I have now gone back to Gingerbread as it does not have full encryption as an option ( so allows me to keep my work exchange account with just a pin password) But I am keen to try ICS again.
Does anyone have any solution for accessing the SD card on an encrypted phone?
Cheers

What would be really interesting if there is a way to password protect the bootloader. Does anyone know?
Best regards,
SuperMaz

Related

Password Protect ADB?

Has anyone thought about implementing password protection to the G1's adb interface? If someone finds (steals) your phone, it' seems like they can get easy access to your data using adb if it is enabled? Instead of forcing the default to adb-debug disabled, it seems like requiring a password would be more useful?
I realize that this might be risky since it might prevent recovery when the password is forgotten, but at that point, there is still the "wipe all my data" unlock method right?
Without this, I find it hard to trust any sensitive data to my phone (since I do not want to toggle adb on/off constantly).
I agree with you any one who find our g1 or steal it, can find easy in the internet how to use adb, or they can even find out how you can do a wipe if you turn the phone off and start the phone using Home+Power button. And they will be good to go to use the G1. I hope someone can add a password protection to this 2 options.
I guess it might be nice to add a password option to the "wipe" option, but that seems like it would sorta defeat the purpose then, wouldn't it?
I am more concerned about my data than the device itself. If someone steals my phone and they can't use it, it doesn't really help me. But, if I can at least prevent them from reading my data... I envision using my phone as a secure token to access various logins at some point (anyone want to code that up? . So, I just want to ensure that they cannot get any keys/passwords on it.
The other problem with preventing someone from wiping it is, "what do you do if you forget your own password"? I would prefer to let the thief use the phone (without my data) than to potentially brick the phone for myself. Lastly, locking it permanently off to thieves would not be a deterrent to theft unless every phone did it since they would not know about it until they stole your phone!
I am surprised that the "serious" hackers have not implemented adb protection yet, have they?
Yea its kinda a good and bad thing tho. Look at it like this .
You put the password on your phone to stop people from doing anything to it, then you forgot your password, how do you get back in? You cant. Unless you have a way around that which if you have a way around that the thief would to.
The only thing i would like is to be able to protect files so if you lost your phone someone wouldn't be able to get into it without wiping the phone.
xile6 said:
Yea its kinda a good and bad thing tho. Look at it like this .
You put the password on your phone to stop people from doing anything to it, then you forgot your password, how do you get back in? You cant. Unless you have a way around that which if you have a way around that the thief would to.
The only thing i would like is to be able to protect files so if you lost your phone someone wouldn't be able to get into it without wiping the phone.
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I agree with you and at the same time don't (right now I don't put personal files in my sd for that very reason if I lost the phone anyone can see what I have on the sd) regarding to the password I guess that it will be up to the people if you know that you forget passwords just don't use it I personally use 2 password 1 for forum 6 letter something simple and easy to remember, and one for (very important stuffs) 12 characteres letters and numbers. Plus I thing that everyone in that will be using this are people to frequent this forum wich I don't think they tend to forget passwords.
In order to gain access to program data (not applicable to sdcard), you still need to be either root, or to possess the userid of the particular program whose data you're trying to gain access to. Use of one of those secure-root password prompt programs will give you the ability to limit root access since the 'su' command will fail without the password being entered in the GUI.
This is not absolute though, since you can still boot on a recovery image, backup, and extract. Without actually encrypting the storage, there is no way to absolutely protect your data, and with a mobile device, the encryption/decryption overhead will take up too much CPU time to be practical. It could, however, be implemented on a program-by-program basis or on a data-but-not-program basis, i.e. encrypt /data/data, or /data/data-enc might be a better idea - leave data for user-programs encrypted, but system-services unencrypted, and mount the encrypted partition on screen unlock (i.e. password unlock). LUKS would be great for this. Allowing optional encryption for SD-card and allowing multiple SD-card partitions to be mounted (i.e. one encrypted, one not) would be ideal.
Well, perhaps the bootloader should get a password also? Would having both an adp and a bootloader passwords secure things completely?
Of course not. Bootloader passwords are virtually useless. All they do is stop you from booting, they do nothing at all to protect your data except from a real amateur, the likes of whom wouldn't be able to get your data off the thing even WITH root access.
As long as there is unencrypted data stored on the device, it definitely can be read off.
Could you please explain why you believe that a bootloader password would not work?
In other words, if a user is locked out from performing commands via the screen without the appropriate gesture, locked out from using adb without a password, and they cannot boot into the recovery image (or access NVRAM with fastboot) without a password, how can they access data on the internal NVRAM? I am not saying they can't (I don't know), I am asking what method you think they could use? Can the NVRAM be easily removed and plugged into another device and read? Are there other boot methods that I am not aware of (likely, I am fairly new to this) that would allow them to access the data? Or, are you just assuming that there is a method that an intelligent cracker could use?
1) you can use fastboot to boot off a recovery image file that is NOT ON THE PHONE,
2) you can connect directly to the chip and read its contents.
etc.
Keep in mind the way that bootloader passwords work; the password is NOT embedded in the bootloader - that would be stupid since you risk bricking the device every time you change the password. A password protected bootloader will access some configuration file that will have the details of the password. Fastboot would (and must) come before this stage.
It seems like you are pretty much just repeating/rewording the weaknesses already pointed out? I am not trying to be rude, if you do have some extra info, or there is something subtle that I am missing, please accept my apologies.
Specifically:
#1 should be assumed to be prevented by the bootloader password, no? Is there any reason you think this would not be effective?
As for #2, I was already asking if the NVRAM could easily be removed from the HTC? Do you have any useful info on this, on what it would take to do it? I assume this would require surface mount de-soldering?
My personal threat model would assume that my data is less valuable to a thief than my phone is. While I would prefer my data to not be easily acquired by a thief, I have nothing so secret that I would expect a thief to specifically steal my phone for it. Therefor, I assume that a thief has no incentive to destroy my phone (which he is in possession of and can use) just to get at my data. Of course, if there is an easy method to get my data (there currently are easy software methods), I would expect a thief to do so. I am hoping to close those easy software methods. If there are easy hardware methods, such as unplugging a chip or sdcard and simply inserting it into another phone, well, then perhaps the software holes are not worth plugging. But, any hardware hacks involving soldering (especially surface mount soldering) the phone are beyond my desire to foil.
Again, that is my personal objective, I understand if you do not share it. Can you think of any additional info that might be valuable with this in mind?
Thanks!
MartinFick said:
#1 should be assumed to be prevented by the bootloader password, no? Is there any reason you think this would not be effective?
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Click to collapse
No, bootloader password won't help you here, and I already explained why.
As for #2, I was already asking if the NVRAM could easily be removed from the HTC? Do you have any useful info on this, on what it would take to do it? I assume this would require surface mount de-soldering?
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Sure, thats one way. The other way is by whatever mechanism HTC uses to initially write the bootloader to the device. I haven't looked, but there is probably a jtag port or something similar on it somewhere.
My personal threat model would assume that my data is less valuable to a thief than my phone is. While I would prefer my data to not be easily acquired by a thief, I have nothing so secret that I would expect a thief to specifically steal my phone for it. Therefor, I assume that a thief has no incentive to destroy my phone (which he is in possession of and can use) just to get at my data. Of course, if there is an easy method to get my data (there currently are easy software methods), I would expect a thief to do so. I am hoping to close those easy software methods. If there are easy hardware methods, such as unplugging a chip or sdcard and simply inserting it into another phone, well, then perhaps the software holes are not worth plugging. But, any hardware hacks involving soldering (especially surface mount soldering) the phone are beyond my desire to foil.
Again, that is my personal objective, I understand if you do not share it. Can you think of any additional info that might be valuable with this in mind?
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Click to collapse
Unfortunately, even if it were possible, securing it against that possibility isn't going to help you since the thief doesn't know that its worthless to him. He'll steal it anyways, and then garbage it when it turns out to be useless to him.
No, bootloader password won't help you here, and I already explained why.
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Uh, no you didn't. You rambled on about the password being in some config file and therefore assumed that it would not be possible or desirable to actually implement a proper bootloader password. I do not accept this criticism, people reflash their bootloaders all the time and it is up to them to determine the level of "brick risk" they want. Perhaps you don't like it, that doesn't make things impossible.
As for putting the password in a config file somewhere, it is not the only solution, one could easily create a separate tiny partition just for the password if you did not want to put FS reading code into the bootloader. (That was your point, right? That the bootloader is simple and cannot read a filesystem?) Surely the bootloader knows how to read partitions, or how would it be able to boot the kernel? With this you could reduce most "brick risk" by providing a "boot from external kernel for recovery after wiping the partitions" option.
And, finally, perhaps there is some other minimal byte storage on the HTC Dream where a password could be easily stored? Something analogous to the CMOS of a PC, something the bootloader could easily read/write to change the password?
Sure, thats one way. The other way is by whatever mechanism HTC uses to initially write the bootloader to the device. I haven't looked, but there is probably a jtag port or something similar on it somewhere.
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Valid concern, easy for someone with the right tools, and some very specialized expertise perhaps. I would be plenty happy to foil all thiefs who do not own such tools or have such knowledge, I believe those are the ones likely to steal my phone.
Unfortunately, even if it were possible, securing it against that possibility isn't going to help you since the thief doesn't know that its worthless to him. He'll steal it anyways, and then garbage it when it turns out to be useless to him.
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Why is not going to help me? If he can't get my data (easily without desoldering), it helps me. I agree and already pointed out that it would not be a deterrent. Nowhere in my objective did deterrence come up.
You make some good points, points that are worthy of serious consideration for anyone attempting to implement this, but I would say that your points hardly make it impossible, in fact, they illustrate very well what a designer would need to consider! Thanks!
I never said that *anything* was impossible. I simply pointed out that IF the password was compiled into the bootloader, then THAT would be extremely dangerous since rather than trying out a tried and true bootloader, every change of password would be a serious brick-risk.
Regarding partition vs file, there is no difference. A partition *IS* a file in a very simple filesystem -- that which we refer to as a "partition table". As such, the risk is identical. I certainly did not suggest that a bootloader is incapable of reading a filesystem, the reverse is in fact, and MUST be true, since if the bootloader couldn't read the filesystem, then how is it to load something that is stored on said filesystem? The point is that if the filesystem were in some manner corrupted, overwritten, updated, etc., then so is your ability to boot the system PERMANENTLY, unless you maintain fastboot prior to the password, in which case it is trivial to boot off a different system image anyways, or unless you go to hardware level to unbrick the device, the same approach, of course, could be used by someone else to gain access.
Oh, and when you say "My personal threat model would assume that my data is less valuable to a thief than my phone is.", that suggests that your priorities are hardware first and then data.
I still say that the most feasible approach to this is selective encryption. Keep the important data from being accessed and not worry about the hardware, since there is no technical way to make it undesirable to a thief except, of course, to make it real ugly. Pack the thing into an old-style Palm case. Take a look into LUKS. It could *definitely* be made to work and is probably easier than you think. What you would have to do is first install support for it at the system level (that might require that you rebuild the kernel), encrypt a partition on the SDCARD with it, and link password, mount, and unmount into the lock screen. Once thats done, you just move and symlink important data onto the encrypted partition. For that matter, you don't even need to automate it with the lock screen, you can just write an app to password, mount, and unmount, or even run it from the terminal. Yes, this is just a linux device. This approach is barely more than trivial.
I never said that *anything* was impossible.
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Sorry, the sentence below sounded like you were implying that it is was impossible.
No, bootloader password won't help you here, and I already explained why.
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Oh, and when you say "My personal threat model would assume that my data is less valuable to a thief than my phone is.", that suggests that your priorities are hardware first and then data.
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No, it suggests that those are the priorties of the thief. I don't believe a thief would steal my phone for its data. I accept that it can be stolen easily or that I might simply leave it on a table in a restaurant or something. At that point I would simply prefer that no one be able to easily snoop my personal affairs. Currently it is VERY easy. I had adb access to my phone before even using the screen, (I needed to register via wifi), it really is simple, it takes little expertise.
Regarding partition vs file, there is no difference. A partition *IS* a file in a very simple filesystem -- that which we refer to as a "partition table". As such, the risk is identical. I certainly did not suggest that a bootloader is incapable of reading a filesystem, the reverse is in fact, and MUST be true, since if the bootloader couldn't read the filesystem, then how is it to load something that is stored on said filesystem?
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Call it what you will, I was giving you the benefit of the doubt.
Many bootloaders do not understand the filesystem they load from, they simply get a pre-created list of the disk blocks to load a kernel from and then load them and execute them.
The point is that if the filesystem were in some manner corrupted, overwritten, updated, etc., then so is your ability to boot the system PERMANENTLY, unless you maintain fastboot prior to the password, in which case it is trivial to boot off a different system image anyways, or unless you go to hardware level to unbrick the device, the same approach, of course, could be used by someone else to gain access.
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For someone who seems to understand things well, you seem to willingly miss important points already mentioned:
With this you could reduce most "brick risk" by providing a "boot from external kernel for recovery after wiping the partitions" option.
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You encryption points are well taken, they probably would be simple to implement, however they would likely have a significant performance impact.
MartinFick said:
You encryption points are well taken, they probably would be simple to implement, however they would likely have a significant performance impact.
Click to expand...
Click to collapse
Only if you're encrypting everything (i.e. programs). There is no reason to encrypt everything -- just encrypt the data you want to protect. There is no reason to bother encrypting apps that you install or the operating system since this is all available elsewhere. If you have private documents, emails, etc., keep those encrypted. The performance impact will be negligible since these files will be fairly small.

[Q] Encryption

Hey there. Can't find any info about encryption and what it brings, so I'll just fire away a few questions about details for that matter. Not that I'm so obsessed with security, more like just curious about the possibility. And keeping things under protection is nice when dealing with business stuff.
What encryption brings? Only data in encrypted, or apps/system too?
Would someone be able to get something from TF by connecting it to a PC? Or he will fail even using ADB or nvflash?
How secure we're speaking about? Any info on encryption method and key length in bits.
If I forget my password, or any other weird thing happen, could I reset it with nvflash, loading new clean images? Maybe encrypted volumes are handled differently, and it's not so easy...
Clockwork Recovery. Would it work perfectly fine with encrypted tablet?
Custom ROMs (like Prime!). Any possible problems when messing with system files without total wipe?
Performance. How bad it could be affected? I'm not sure Tegra2 has RSA-optimized module built-in (or whatever method it's using).
Unlocking. Will I be prompted to enter password every time I see unlock screen, or only when I reboot?
Any known limitations, like password length (I like to set long passwords, it's more efficient and easier to remember).
Bump - heard that HC 3.2 enabled encryption at last. Anyone tried it and can answer any of my questions?
Never done it myself, but from information I read:
tixed said:
Hey there. Can't find any info about encryption and what it brings, so I'll just fire away a few questions about details for that matter. Not that I'm so obsessed with security, more like just curious about the possibility. And keeping things under protection is nice when dealing with business stuff.
What encryption brings? Only data in encrypted, or apps/system too?
Would someone be able to get something from TF by connecting it to a PC? Or he will fail even using ADB or nvflash?
How secure we're speaking about? Any info on encryption method and key length in bits.
If I forget my password, or any other weird thing happen, could I reset it with nvflash, loading new clean images? Maybe encrypted volumes are handled differently, and it's not so easy...
Clockwork Recovery. Would it work perfectly fine with encrypted tablet?
I guess this should be fine.
Custom ROMs (like Prime!). Any possible problems when messing with system files without total wipe?
Performance. How bad it could be affected? I'm not sure Tegra2 has RSA-optimized module built-in (or whatever method it's using).
I read that this would have lesser performance since it has to be decrypted on fly and also affects battery.
Unlocking. Will I be prompted to enter password every time I see unlock screen, or only when I reboot?
I guess every time when you unlock.
Any known limitations, like password length (I like to set long passwords, it's more efficient and easier to remember).
Click to expand...
Click to collapse
I found THIS little tid bit after a Google search.
I do know that it does NOT encrypt your removable MicroSD card or SD card. The encryption can take a considerable amount of time to encrypt all your data (1 to 3 hrs and has to be powered on and at 100%). It will require a PIN or Password prompt at power on and possibly for other data sensitive action. It will also allow for password mining which is the process by which you are required to reenter a new password after so long. Also once you encrypt the only way back is a factory reset. If you lose your PIN or Password your SOL about getting your sensitive data back.
You might be better off using an app that can encrypt individual files that you choose.
Cheers...
tixed said:
What encryption brings? Only data in encrypted, or apps/system too?
Would someone be able to get something from TF by connecting it to a PC? Or he will fail even using ADB or nvflash?
How secure we're speaking about? Any info on encryption method and key length in bits.
If I forget my password, or any other weird thing happen, could I reset it with nvflash, loading new clean images? Maybe encrypted volumes are handled differently, and it's not so easy...
Clockwork Recovery. Would it work perfectly fine with encrypted tablet?
Custom ROMs (like Prime!). Any possible problems when messing with system files without total wipe?
Performance. How bad it could be affected? I'm not sure Tegra2 has RSA-optimized module built-in (or whatever method it's using).
Unlocking. Will I be prompted to enter password every time I see unlock screen, or only when I reboot?
Any known limitations, like password length (I like to set long passwords, it's more efficient and easier to remember).
Click to expand...
Click to collapse
Had a brief experience with encryption before I wiped back to stock. I would strongly recommend against it unless you wish to stick to a stock system and very much need that type of security. From what I remember of my experience:
The data partition is encrypted (not sure what else, but not MicroSD). When your device boots, a prompt that somewhat resembles a lockscreen pops fairly early on when the OS attempts to mount those partition(s). Thereafter, everything is accessible as usual; you can grab things via ADB. You do not have to constantly enter the password (though you would probably want to lockscreen your device as general good practice). As to what nvflash would get you, I'm not sure, since that would be before the partition mount...probably nothing usable. The problem with having an encrypted partition is that CWM at moment can't really do anything useful to those partitions. You cannot flash, backup, or restore via CWM. This means your ability to work with custom ROMs is effectively crippled. In fact, to undo the encryption (or if you forget your password), I had to nvflash back to stock. Factory reset via CWM cannot be done since, again, the partitions are still encrypted.
If in the future, CWM is able to access the partitions like the stock recovery can, then you'd be fine. Performance was not noticeably slower in anyway.
Thanks for the replies. This feature seems pretty grim at the moment. Well, we can all hope that Google and ASUS will update it properly. At least, they did a lot of good updates recently.

[Q] Full device encryption in Sensation with official ICS?

Hi!
First time post, but long time lurker here
Long background:
We have a bit of confusion here at work after the official relase of ICS for the HTC Sensation. We currently have a third party mail solution (DME) that is used to make sure all mail data is encrypted on the device in case of theft. Therefore the full device encryption in ICS has been very much on our "need to have list" to be able to enforce the Exchange policy of "require encrypted device" to make it possible to user ActiveSync instead of the painful DME solution....
So, on the Galaxy Nexus we have the option of "Encrypt phone" for full device encryption (not sure if this is the exact name in English as we have Swedish localization). After that it works fine to connect via ActiveSync to the Exchange server that has the policy of "require encrypted device" (and "require encrypted SD card too - as the Nexus does not have one)...
On the HTC Sensation however, we cannot find the option to "Encrypt the phone" (full device encryption), but only the option of "Encrypt SD card". The Exchange server does not allow the Sensation to sync if just the SD card is encrypted, and our security department will not allow it if the whole device is not encrypted...
So - the question:
Is it not possible to enable full device encryption in HTC:s implementation of ICS? Encrypting the SD card will not be good enough as the mail data is stored in the internal memory and not the SD card? Besides, the people here with Sensations are having problems accessing the data on the SC-card after encrypting it - but that's another question
Any ideas?
I found and posted the official not yet realeased Sensation ICS users guide:
http://forum.xda-developers.com/showthread.php?t=1546297&highlight=user+guide
It ha sa section on encryption, it might help
I have read that manual (its for HTC Sens. XE) and it says:
1. From the Home screen, press , and then tap Settings.
2. Tap Storage.
3. Tap Storage encryption to encrypt the phone storage or SD card encryption
--The option "Storage encryption" does not exist on the HTC Sensation.
So the question still remains unsolved. Is it possible to do a full device encryption on the HTC Sensation?
Any takers?
/Naper
There are two options for the ICS Sensation, you will need to enable both
Settings->Storage
Storage Encrytion = Encrypt applications and settings
SD Card Encrytion = Requires SD card to be encrypted. Non-encrytped SD card will be read only.
Hi,
like i said, the option "storage encryption" is not available on my ICS Sensation,
and not on my collegues either.
so other ideas?
What version of ICS are you running?
One thing I noticed is that if you have connected to an exchange server some security settings disappear once a policy has been set, ie install from unknown sources is one I saw remove after connecting to my mail server. It could be that your policy is actually active and has been removed from the menu.
The only way to check would be to factory default your handset and check for the settings, then connect to your exchange server and check again.
Hi,
reply from HTC:
----
Storage encryption is an option that that the 2.3.5 update with HTC sense 3.5 had and is something you cannot find in either the Sensation or Sensation XE after updating to ICS. After the update the device will use this function automatically if it is required to.
----
Unfortuneately using exchange 2010 with both sd card encryption and storage encryption policy does not work. When syncing phone with exchange, it tells you that you ppolicies needs to be applied. First sd-card. when its done and in the next sync it tells you yet again there still are polices that needs to be applied on the moblie. Pressing ok and nothing happens after that. This dialog reappear the next time the phone sync and so on...
Any solution yet?
Did you find a solution to your Exchange problem?
It sounds like the same problem as I described here: http://forum.xda-developers.com/showthread.php?t=1541079
I have send a support request to HTC about this 14 days ago, but no solution yet.
Bumping because this is a huge issue for me. If I had known I would not have upgraded.
MobileIron is having a fit because it wants device encryption enabled, but the option to turn it on is not in the OTA update I have received. It worked fine in Gingerbread OTA because Gingerbread did not support encryption, but for devices that support encryption it is mandatory. Because of this I can't receive work e-mail on my phone. The value my phone provides is severly diminished.
I see three options:
1. Something I'm missing that fixes this.
2. Flash back to Gingerbreat OTA (Is this even possible without root? MobileIron will not allow me to receive work e-mail if the device is rooted.)
3. Flip T-Mobile the bird and go to Sprint, and sell the Sensation to make back some of the ETF.
Anyone else have anything?
If you use the ICS skin mod, the option appears to use it. I tested it on the non tmob rom.
I think if I got rid of sense and used the usual launcher it worked. Why it isn't there is beyond me. I tested it and it did work, but do a backup first.
http://forum.xda-developers.com/showthread.php?t=1470497
Well, of course, if you are running the official rom it won't work, cause you need to be running something like ARHD to use that mod
Hi!
I have an HTC Sensation XL, and recently after I updated to ICS, everything was there, including the "storage encryption" option which is automatically enabled for apps and settings. If you were prompted to add a pin code and so, then it means your phone is probably already encrypted.
One thing you should note though is that, the "phone storage encryption" will wipe out all the data in your phone storage first and then encrypt the storage, so doing a backup first would be helpful. I didn't know about this when I performed the encryption process, and so all my precious photos were wiped out...and no way to recover even with a data recovery software
If anyone could help me out with this, it would be greatly appreciated
I am running AOSP and "Encrypt Phone" is under the security tab in settings. Maybe HTC removed it in sense.

[Q] Broke the glass on my screen, now I have to give my phone to a technician...

Don't worry, it's a security question alright.
I live in Eastern Europe, which is on the far side of the Samsung support network and I have samsung galaxy s3 phone (GT-9300 i guess). My repair options look a little bit bleak. I must either ship it back to France, from where it is bought, or I must seek help of non-licensed technicians. Thank God, there are quite a lot around here and for problems like this they do wonders.
I am worried though that the technicians may try to meddle with the software of my phone and do something nasty with it while the phone is in their possession. I use the phone quite a lot to access various servers trough ssh and the servers contain semi-sensitive information about customers, phones, the equivalents of social security numbers in my country and etc. Of course I will delete my present information, but how about the future. If someone has hacked versions of the firmware, it will be a child game to get the passwords for my servers.
So I need to secure the software of my phone somehow and I'm not sure of my options, so I'm asking for advice which is better. I have experience with Linux, but about Android I'm a quite noob. I had my Amazon FireHD Tablet rooted and installed with CyanogenMOD, so I know a little bit about ROM images. The phone itself is unrooted with original software and is not locked to a carrier.
Should I:
1. Try to back up my entire ROM image?
There are various questions here. It looks that I cannot download standalone original ROM image directly from Samsung so I must back up mine. But in the bootloader (which opens with volume up/down + home + power) it seems that there are no options for backing up rom image, only for restoring trough ADB of SD card. Should I try to root, install alternative bootloader and then back up everything.
There is one very important sub-question here: Will the phone signal me somehow If someone replaces the original bootloader with say, non-signed one? What If someone changes the bootloader as well as the system image?
2. Should I try to ecrypt my phone.
I cannot get easily information about what exactly is encrypted. Pretty sure that the bootloader itself cannot be encrypted anyway. How about the system image. Is it encrypted ?
I'll be thanful for any help about these two ideas as well as any others?
If you are paying to have the repair done by an entity other than Samsung then you have a great option available. Just out of curiousity, what version of android are you running? If I were in your shoes, I would root the phone and install a custom recovery (either TWRP or Philz). This will allow you to take a complete nandroid backup of the phone to the external SD Card. Confirm the nandroid backup has been saved to the SD Card then remove the card from the phone and store it somewhere safe. Then perform a factory reset to completely wipe the phone and have your phone sent out to be fixed. When you get your phone back, insert the SD Card and restore from the backup. It will be just as you left it and the possibility that anyone has been able to access or tamper with your phone is almost nil... Apart from possibly large national security agencies whom are known for having catalogs of common electronic items that have been compromised in various ways.
I can't speak for your exact phone, but I am quite familiar with encryption as well as the US-model Galaxy S3's. Unfortunately Samsung is known for running their own encryption schemes with are different and most often weaker than the stock. Custom ROMs with generally have an implementation based on AOSP sources. A 4 digit PIN or common passphrase can be easily broken with either, but a sturdy encryption passphrase will almost certainly provide sufficient protection.
Without knowing the specifics of your phone and whatever TouchWiz it's running, I can say this much. If you enable encryption on your phone, it will encrypt /data (application data) at a very minimum. This will almost definitely not include /system. It will probably not include the external SD card or any of the actual applications (the .apk files). The encryption would keep your data secure at rest, but it wouldn't prevent a motivated attacker from installing a hidden malicious application in the system.
You are correct in that the bootloader cannot be encrypted.
84598432951
fadedout said:
If you are paying to have the repair done by an entity other than Samsung then you have a great option available. Just out of curiousity, what version of android are you running? If I were in your shoes, I would root the phone and install a custom recovery (either TWRP or Philz). This will allow you to take a complete nandroid backup of the phone to the external SD Card. Confirm the nandroid backup has been saved to the SD Card then remove the card from the phone and store it somewhere safe. Then perform a factory reset to completely wipe the phone and have your phone sent out to be fixed. When you get your phone back, insert the SD Card and restore from the backup. It will be just as you left it and the possibility that anyone has been able to access or tamper with your phone is almost nil... Apart from possibly large national security agencies whom are known for having catalogs of common electronic items that have been compromised in various ways.
I can't speak for your exact phone, but I am quite familiar with encryption as well as the US-model Galaxy S3's. Unfortunately Samsung is known for running their own encryption schemes with are different and most often weaker than the stock. Custom ROMs with generally have an implementation based on AOSP sources. A 4 digit PIN or common passphrase can be easily broken with either, but a sturdy encryption passphrase will almost certainly provide sufficient protection.
Without knowing the specifics of your phone and whatever TouchWiz it's running, I can say this much. If you enable encryption on your phone, it will encrypt /data (application data) at a very minimum. This will almost definitely not include /system. It will probably not include the external SD card or any of the actual applications (the .apk files). The encryption would keep your data secure at rest, but it wouldn't prevent a motivated attacker from installing a hidden malicious application in the system.
You are correct in that the bootloader cannot be encrypted.
Click to expand...
Click to collapse
Thank You for the informative answer!
I had to do this once and what I did was:
- Root phone (which I always wanted to do)
- Perform a full backup to SD card
- Remove SD card and perform a factory reset of the phone
Then off to repairs.
Once back, I did again a factory reset (just in case) and then restore the lot
Seems a lot to do, but I have some sensitive data on it and didn't want to risk it too much. Besides during the restore I took the opportunity to upgrade to 4.3 (at the time)
glass
why dnt you buy a chinese glass and change it yourself its so easy and cheap, around 10 euros or so? i did the same for my old phone

Making the S8+ completely theft proof

Hey!
It's my first post here so it this isn't the best place for such a question then by all means mods pls move the thread to where it should be
Basically, where I'm currently living (Brazil), things tend to get pretty violent and phone thefts are very common. Now the thing is, if it's an iPhone usually the thieves just throw it away, as once it's locked it becomes useless. When it comes to Android though, some of them will dig deep trying to access your info like pictures, passwords, bank information, among other things. They even manage to break IMEI locks and stuff. I got my S5 stolen recently and the information theft part put me through hell. Yet, I'd much rather have an S8+ then any other iPhone currently, so my question is how could I completely theft proof it?
I'm not really worried about them restoring the phone and reselling it, more about them accessing the data inside of it. I know the SD card can be protected through cryptography (although would accept "stronger" tips if there are any). When it comes to apps, aside from the basics of trusting what you install and stuff, are apps like Cerberus, Knox 2.0, or other Samsung features I'm not aware of, any good against someone who knows what they're doing? Is there a way to disable airplane mode or power offs? Also what is probably my strongest concern: is there a way to completely not allow system changes through a computer, like the one that removes the lock screen?
Being a programmer and computer science undergrad student (although not specializing in security nor mobile), I'd have no problem if the solutions would involve some coding or tweaking, just as long as they prove to be effective.
So, would you guys have any tips on how to completely secure the data given those concerns?
The sd card can be Encrypted and if you have a password lock (fingerprint irsi etc...) then it will ask for that before it will unlock the phone.
Also they have a remote wipe. You can log i to google and remote wipe your phone when you found out its been stolen.
You can set the phone to require a password to decrypt it when it's restarted. You can encrypt the SD card too. You can set it to lock instantly when the screen turns off. And you can use only a password to unlock it (no biometrics), which is the most secure option (if you use a suitable password). Finally, you can set the phone so that you can wipe it remotely, or to wipe itself after a number of consecutive incorrect password attempts. But even without the last two measures, your data will be unreadable without your password.
Unfortunately, though, if thieves are violent enough, they may be able to coerce you into divulging the password. If they succeed, they have full access to your phone.
Gary02468 said:
You can set the phone to require a password to decrypt it when it's restarted. You can encrypt the SD card too. You can set it to lock instantly when the screen turns off. And you can use only a password to unlock it (no biometrics), which is the most secure option (if you use a suitable password). Finally, you can set the phone so that you can wipe it remotely, or to wipe itself after a number of consecutive incorrect password attempts. But even without the last two measures, your data will be unreadable without your password.
Unfortunately, though, if thieves are violent enough, they may be able to coerce you into divulging the password. If they succeed, they have full access to your phone.
Click to expand...
Click to collapse
What about stuff like that Dr. Fone Toolkit that supposedly removes the lock screen? From the quick look I took it seems it somehow patches the Android on the phone to remove the lock screen. Is there some sort of system encryption/lock to avoid that kind of stuff when connected to a computer?
xile6 said:
The sd card can be Encrypted and if you have a password lock (fingerprint irsi etc...) then it will ask for that before it will unlock the phone.
Also they have a remote wipe. You can log i to google and remote wipe your phone when you found out its been stolen.
Click to expand...
Click to collapse
Usually they just put it on airplane mode though, so google remote wipe is useless... Which is why I was looking for more of an offline fix through cryptography and such
I use smart Lockscreen protector to prevent somebody putting my phone to airline mode or shutting it down ( It won't help phones with removable battery)
If you have the phone encrypted and have the require pin on boot set. And you have the Qualcomm version that is locked down you have nothing to worry about.
Even the iPhone 7 has been jail broken or rooted the S8 with the Qualcomm chip is one of only a few phones that have not been hacked. It's actually WAY more secure than an iPhone.
lvrma said:
What about stuff like that Dr. Fone Toolkit that supposedly removes the lock screen? From the quick look I took it seems it somehow patches the Android on the phone to remove the lock screen. Is there some sort of system encryption/lock to avoid that kind of stuff when connected to a computer?
Click to expand...
Click to collapse
The phone is completely encrypted, so if you set it to require a password to restart and to turn the screen back on, then its contents are unreadable without the password regardless of how you connect to it.
lvrma said:
...
Usually they just put it on airplane mode though, so google remote wipe is useless... Which is why I was looking for more of an offline fix through cryptography and such
Click to expand...
Click to collapse
If you have a lock screen set you can lock the status of your phone(wifi state, airplane mode, power settings). This way you have to unlock it to toggle these modes.
I just ran across this, some good advice.
http://thedroidguy.com/2017/04/setu...security-features-tutorials-1071462#Tutorial1
lvrma said:
What about stuff like that Dr. Fone Toolkit that supposedly removes the lock screen? From the quick look I took it seems it somehow patches the Android on the phone to remove the lock screen. Is there some sort of system encryption/lock to avoid that kind of stuff when connected to a computer?
Click to expand...
Click to collapse
Like you, I'm interested with this topic, but unlike you, I would like the theief to have a useless phone if they cant unlock it. So that they would think twice the next time they want to steal an android. Else they would just continue stealing since you just put the phone on download mode, connect to a computer and root it.
About your question. Isnt disabling usb debugging mode on developer option block that risk? Also in my note 4, enabling knox will prevent your device from being rooted, at least thats what i understand from the description. i wonder where it is in s8.
speaking of knox, s8 has "Secure folder". its like a secured environment within a phone. Everything you put in here will be protected by knox. Apps, accounts, files, etc. And it would ask for another security to access it(pattern/pin/password).
lvrma said:
Usually they just put it on airplane mode though, so google remote wipe is useless... Which is why I was looking for more of an offline fix through cryptography and such
Click to expand...
Click to collapse
you mentioned cerberus app, it has a function than can wipe device memory and wipe sd card via SMS command. so if you are fast enough, while the thief is running away and before he pulls out your sim card from the phone, you can send an sms command to wipe data.
Since you mentioned you are a programmer, this may be interesting to you, locking download mode and recovery mode on android to prevent thief from flashing hack to your phone. but this require a bit of patience if android isnt your forte.
https://ge0n0sis.github.io/posts/20...-mode-using-an-undocumented-feature-of-aboot/
BratPAQ said:
Like you, I'm interested with this topic, but unlike you, I would like the theief to have a useless phone if they cant unlock it. So that they would think twice the next time they want to steal an android. Else they would just continue stealing since you just put the phone on download mode, connect to a computer and root it.
About your question. Isnt disabling usb debugging mode on developer option block that risk? Also in my note 4, enabling knox will prevent your device from being rooted, at least thats what i understand from the description. i wonder where it is in s8.
speaking of knox, s8 has "Secure folder". its like a secured environment within a phone. Everything you put in here will be protected by knox. Apps, accounts, files, etc. And it would ask for another security to access it(pattern/pin/password).
you mentioned cerberus app, it has a function than can wipe device memory and wipe sd card via SMS command. so if you are fast enough, while the thief is running away and before he pulls out your sim card from the phone, you can send an sms command to wipe data.
Since you mentioned you are a programmer, this may be interesting to you, locking download mode and recovery mode on android to prevent thief from flashing hack to your phone. but this require a bit of patience if android isnt your forte.
https://ge0n0sis.github.io/posts/20...-mode-using-an-undocumented-feature-of-aboot/
Click to expand...
Click to collapse
Don't put your phone anywhere besides your pocket. Get a cover that makes it look like as different phone with a cracked screen.
the easiest way to encrypt sd and phone, enable adoptable storage.
cantenna said:
the easiest way to encrypt sd and phone, enable adoptable storage.
Click to expand...
Click to collapse
How is that easier than just selecting the Settings options to encrypt the SD card and to require a password to unlock upon restart?
---------- Post added at 06:08 AM ---------- Previous post was at 05:11 AM ----------
lvrma said:
Usually they just put it on airplane mode though, so google remote wipe is useless[.] Which is why I was looking for more of an offline fix through cryptography and such
Click to expand...
Click to collapse
Yes, and even without airplane mode, they can physically enclose the phone to block all electronic signals. Encrypting the phone (and SD card), using a secure password as the sole unlock method, affords the strongest protection against all attacks (except coercing the password from you).
Gary02468 said:
How is that easier than just selecting the Settings options to encrypt the SD card and to require a password to unlock upon restart?
---------- Post added at 06:08 AM ---------- Previous post was at 05:11 AM ----------
Yes, and even without airplane mode, they can physically enclose the phone to block all electronic signals. Encrypting the phone (and SD card), using a secure password as the sole unlock method, affords the strongest protection against all attacks (except coercing the password from you).
Click to expand...
Click to collapse
oh yea, may bad, i often assume everyone on xda is here because there interested in unlocked boot loaders, root and custom kernels. My recomindation applies only to people who have unlocked pandor's box only.
the method of encyption you suggested the isnt availble for users like me but we can enable adoptable storage which does encrypt the system by other means and it is compatible with root, etc
dynospectrum said:
Don't put your phone anywhere besides your pocket. Get a cover that makes it look like as different phone with a cracked screen.
Click to expand...
Click to collapse
Where can you get/ how can you make such a cover?
Also sometimes when I'm in bad Areas, I go to developer options and turn on some of the screen update stuff, so it flashes the screen purple a lot and make it look messed up.

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