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[Q] Data Encryption feature in TF

HI All,
has anyone used the Data Encryption feature on the TF? Are there any known issues? I want to be able to secure my personal data and also my work data stored on my TF.

I was too afraid as every encryption software we have tried in my company has caused performance hits. It's probably the same with the TF.

Kilmar said:
I was too afraid as every encryption software we have tried in my company has caused performance hits. It's probably the same with the TF.
Click to expand...
Click to collapse
That's exactly what I was afraid of too... But there has to be another way to protect my private data and work data...
Mike

I don't think encryption should cause any performance issues. The storage should be decrypted upon boot and then behave normally. That's how laptop full disk encryption works anyway, no performance hit.
The only downside I can see is issues with recovery software etc...
I'm not sure what it encrypts exactly. Maybe just user data? Just the SD card? Full flash?
Sent from my Nexus S using XDA Premium App

csmall said:
I don't think encryption should cause any performance issues. The storage should be decrypted upon boot and then behave normally. That's how laptop full disk encryption works anyway, no performance hit.
The only downside I can see is issues with recovery software etc...
I'm not sure what it encrypts exactly. Maybe just user data? Just the SD card? Full flash?
Sent from my Nexus S using XDA Premium App
Click to expand...
Click to collapse
mind if i ask you where you got this information? it doesn't really make any sense. decrypting an entire drive would be incredibly slow.

finalhit said:
mind if i ask you where you got this information? it doesn't really make any sense. decrypting an entire drive would be incredibly slow.
Click to expand...
Click to collapse
You wouldn't decrypt the entire volume at once though, just what you were trying to access.

You don't actually have to decrypt the disk to access it. It has the key so it can just gain access. The drive is still encrypted, you just can access it. I may not be wording it properly.
Actually decrypting a disk will take time yes. But that isn't the case with accessing it.

that's how i understand encryption works. the password you use merely unlocks the key which is used to decrypt files on demand. of course, the decryption does take a toll on performance, especially on system files that get accessed often.
so it wouldn't be completely without a performance hit.
i do use full encryption on my ubuntu install (i believe including swap) and although it's not noticeable most of the time, i think when things get busy, i does add some overhead.

[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.

Lollipop - Enabled encryption. Not sure if it worked

Hey guys
I flashed the factory images last night effectively wiping my Nexus 5 and starting from scratch. I did not restore apps and settings either. After I manually installed a bunch of my apps back and changed around a few settings, I decided to enable encryption. However, I don't think it enabled properly.
First, I had not set a PIN lock on my phone yet at the time.
When I decided to enable encryption and go through the process, it didn't ask me to enter a PIN.
It seemingly completed encrypting the phone. When I go back to the security menu, it says "Encrypted".
However, I am not prompted to enter a PIN upon booting the phone (not talking about the lock screen PIN).
So, it seems like it didn't work but I'm not sure. Has anyone else enabled encryption yet?
and yes, I saw the performance degradation that comes with enabling encryption but I'd rather have the security.

definitely sounds like there's an issue there. Do you have a custom recovery? If so, you could boot into that, pull some data and see if it opens. If it does, yeah its not encrypted.
Not worth mentioning degradation. All encryption always has and always will have performance degradation. It's par for the course

That sounds like a good idea. If it's not encrypted, then I guess the only method is to wipe and reinstall again.

mattkroeder said:
That sounds like a good idea. If it's not encrypted, then I guess the only method is to wipe and reinstall again.
Click to expand...
Click to collapse
I think so. You can't reverse the encryption flag without a wipe I dont think

mattkroeder said:
Hey guys
I flashed the factory images last night effectively wiping my Nexus 5 and starting from scratch. I did not restore apps and settings either. After I manually installed a bunch of my apps back and changed around a few settings, I decided to enable encryption. However, I don't think it enabled properly.
First, I had not set a PIN lock on my phone yet at the time.
When I decided to enable encryption and go through the process, it didn't ask me to enter a PIN.
It seemingly completed encrypting the phone. When I go back to the security menu, it says "Encrypted".
However, I am not prompted to enter a PIN upon booting the phone (not talking about the lock screen PIN).
So, it seems like it didn't work but I'm not sure. Has anyone else enabled encryption yet?
and yes, I saw the performance degradation that comes with enabling encryption but I'd rather have the security.
Click to expand...
Click to collapse
Not sure, but i think it's designed to works just like that, the encryption key is not the PIN anymore but something (random?) that is stored somewhere on the phone.
that would protect the data in case someone tries to read it directly from the phone's memory, but useless if you don;t have a PIN/PASSWORD.
I avoided encryption before for exactly that reason (requiring a password to boot). If I lose the phone I want the person that found/stole it to be able to at least boot it. if the person is not a thief there's a contact number so they can call me to give it back. if he/she's a thief well, as long as it's on I can call it, track it, wipe it. even brick it.
by not being able to boot it, the chances of getting it back are 0 if the battery dies or is dead!
http://readwrite.com/2014/10/28/google-android-lollipop-encryption-issues
there isn't much info out there about it.

kenshin33 said:
Not sure, but i think it's designed to works just like that, the encryption key is not the PIN anymore but something (random?) that is stored somewhere on the phone.
that would protect the data in case someone tries to read it directly from the phone's memory, but useless if you don;t have a PIN/PASSWORD.
I avoided encryption before for exactly that reason (requiring a password to boot). If I lose the phone I want the person that found/stole it to be able to at least boot it. if the person is not a thief there's a contact number so they can call me to give it back. if he/she's a thief well, as long as it's on I can call it, track it, wipe it. even brick it.
by not being able to boot it, the chances of getting it back are 0 if the battery dies or is dead!
http://readwrite.com/2014/10/28/google-android-lollipop-encryption-issues
there isn't much info out there about it.
Click to expand...
Click to collapse
I went ahead and wiped the phone again. I reinstalled lollipop and made sure to enable a lockscreen PIN before I enabled encryption. It seems to have encrypted properly. It prompts me for my PIN at boot up now.
You make a good point about encryption making it more difficult for someone to get a hold of me if I lose the phone though.

Same problem here, with Nexus 5 and Android v5
My work Exchange server enforces a security policy to the phone which forces you to enable encryption. So I went ahead and did that, and the email app is still saying that encryption needs to be enabled. When I reboot the phone I never get prompted for a PIN to decrypt the device, yet in the settings screen it says it is encrypted.
I'm going to have to re-flash. Is it possible the issue is caused by leaving the bootloader unlocked? or is this is a bug?
EDIT: Update. Reflashed, but first thing I did was relock the bootloader and enable a security screenlock PIN, *then* encrypted the phone. Now it's prompting me for a PIN on boot and looks like it's worked. Hope the Exchange email policy stays happy this time, as it worked before for about a day before it complained about the lack of encryption

this worked for me also
I did what was stated below and it worked....
1. reflashed,
2. locked bootloader
3. created lock pin
4. encrypted, THEN
5. added MDM control (MAAS360) and exchange email.
It seems to work OK now.
Thanks!
JoyrexJ9 said:
Same problem here, with Nexus 5 and Android v5
My work Exchange server enforces a security policy to the phone which forces you to enable encryption. So I went ahead and did that, and the email app is still saying that encryption needs to be enabled. When I reboot the phone I never get prompted for a PIN to decrypt the device, yet in the settings screen it says it is encrypted.
I'm going to have to re-flash. Is it possible the issue is caused by leaving the bootloader unlocked? or is this is a bug?
EDIT: Update. Reflashed, but first thing I did was relock the bootloader and enable a security screenlock PIN, *then* encrypted the phone. Now it's prompting me for a PIN on boot and looks like it's worked. Hope the Exchange email policy stays happy this time, as it worked before for about a day before it complained about the lack of encryption
Click to expand...
Click to collapse

mattkroeder said:
Hey guys
I flashed the factory images last night effectively wiping my Nexus 5 and starting from scratch. I did not restore apps and settings either. After I manually installed a bunch of my apps back and changed around a few settings, I decided to enable encryption. However, I don't think it enabled properly.
First, I had not set a PIN lock on my phone yet at the time.
When I decided to enable encryption and go through the process, it didn't ask me to enter a PIN.
It seemingly completed encrypting the phone. When I go back to the security menu, it says "Encrypted".
However, I am not prompted to enter a PIN upon booting the phone (not talking about the lock screen PIN).
So, it seems like it didn't work but I'm not sure. Has anyone else enabled encryption yet?
and yes, I saw the performance degradation that comes with enabling encryption but I'd rather have the security.
Click to expand...
Click to collapse
If you set up a screen lock pin the phone will ask you then if you would like the PIN to be enabled or not at boot.

kenshin33 said:
Not sure, but i think it's designed to works just like that, the encryption key is not the PIN anymore but something (random?) that is stored somewhere on the phone.
that would protect the data in case someone tries to read it directly from the phone's memory, but useless if you don;t have a PIN/PASSWORD.
I avoided encryption before for exactly that reason (requiring a password to boot). If I lose the phone I want the person that found/stole it to be able to at least boot it. if the person is not a thief there's a contact number so they can call me to give it back. if he/she's a thief well, as long as it's on I can call it, track it, wipe it. even brick it.
by not being able to boot it, the chances of getting it back are 0 if the battery dies or is dead!
http://readwrite.com/2014/10/28/google-android-lollipop-encryption-issues
there isn't much info out there about it.
Click to expand...
Click to collapse
Sorry for OT, but how can you remotely brick your phone? Just curious in case I ever need to. Don't live in the best of neighborhoods. I can remote wipe, track, take pics. The normal lost/stolen stuff, but I haven't heard of remotely bricking a phone ever.

Nexus 5 still looking to be encrypted
Only a temp fix---Both my Nexus 7, and Nexus 5 just started asked to be encrypted again....
This is still a problem with Lollipop
thegasmaster said:
I did what was stated below and it worked....
1. reflashed,
2. locked bootloader
3. created lock pin
4. encrypted, THEN
5. added MDM control (MAAS360) and exchange email.
It seems to work OK now.
Thanks!
Click to expand...
Click to collapse

wipe efs partition (I do have a backup on my computer) and the phone is no longer a phone.

Just to be clear, you can enable encryption on Android 5.0, and it will not force you to lock the phone. (Like the PIN screen and boot lock). When you buy a Nexus 6/9 the data partition is encrypted but there's no lock set. The following is from this article;
First, the encryption doesn't help much if you haven't set a passcode. Ludwig said studies have shown that roughly have of users don't set passcodes on their devices, largely because they find it inconvenient to keep entering them dozens of times a day. Lollipop will still encrypt your data, but it will also automatically decrypt it in normal use. So if you don't have a passcode, much of your information will be available to anyone who picks up your phone.
Click to expand...
Click to collapse
So if you've enabled encryption, and gone through the process, you're phone data partition is encrypted. It's just not locked down until you use some kind of phone lock too. BTW, the article goes on to describe the limited usefulness of having an encrypted data partition and no phone lock;
Lollipop's encryption still offers some limited protection even under those circumstances—for instance, by protecting stored data against anyone who tries to read it directly from the phone's memory. That could shield user passwords and other sensitive data from attackers.
Click to expand...
Click to collapse
As to why Exchange policies don't see the phone as encrypted is probably due to another issue.

Setting PIN to be required at startup after encryption possible fix
I now have my Nexus 5 & 7 working with exchange on Lollipop using this-
1. Reflashed Lollipop
2. Let phone reinstall all my apps
3. Locked bootloader.
4. Set a screen lock PIN
5. Encrypt phone
6. Set screen lock PIN to be required on start up (this was missing before!)
7. Installed MDM control via Mass360-all policies look to be met, including encryption
8. Installed my exchange account via Gmail
//code.google.com/p/android/issues/detail?id=79342

Updated thread with solution
---
* It used to be that when I did a reboot or shutdown and restart, I would have to enter a password before the system fully started.
* But now the phone boots into the phone without putting in my password. I can reboot the phone and it will boot all the way to the Lock screen, and I can unlock the lock screen with my fingerprint or my backup password.
* I am concerned that somehow my device is either no longer encrypted or that there is some setting which has stored the boot password.
--
Solution :
For those of you who find they have this problem and have not solved it, I found a solution that works, related to a bug (feature?) in Accessibility.
Apologies if this was suggested further in the thread, and that I'm replying to an old post. But I recently had this problem and figured out a solution.
- Accessibility was enabled and for some reason this cached the boot password. So- when I removed the app (rights) and turned off accessibility, and changed (reset/reentered) the password in security settings... On next boot the phone correctly asked me for password.
YMMV.

subs said:
I posted this elsewhere... But I'm having the same problem. Any thoughts? I can post more details, but don't want to repost this everywhere that I see people having the same unresolved problem.
---
* It used to be that when I did a reboot or shutdown and restart, I would have to enter a password before the system fully started.
* But now the phone boots into the phone without putting in my password. I can reboot the phone and it will boot all the way to the Lock screen, and I can unlock the lock screen with my fingerprint or my backup password.
* I am concerned that somehow my device is either no longer encrypted or that there is some setting which has stored the boot password.
Click to expand...
Click to collapse
Hi, please try not to bump threads almost a year old. I realise that it might have taken you a while to actually reach this thread, but hear me out.
Opening a new thread is always better, since software versions, features and devices are most likely different, along with different device usage habits/users.
You say you're having "the same problem"... as.. who exactly? There's a bunch of different specific "issues" that relate to encryption. Be specific.
For instance, you mentioning fingerprint sensor leads me to presume that you are not using a Nexus 5.
Sent from my Nexus 10 using Tapatalk

No way to require passphrase on startup!

I just got my pixel, and found two very bitter disappointments. First, as expected, even an unrooted device will not pass safetynet (i.e., let you run android pay) if you've unlocked the bootloader.
Second, however, and a bit more of a shock, there appears to be no way to require a passphrase on bootup. The option on the nexus 5X and 6P that you get while selecting a PIN simply does not exist. So does this mean there is basically no way to secure my phone?
This is doubly infuriating. On one hand Google wants to prevent me from learning my own device encryption keys, supposedly in the name of security. But then on the other hand, they reserve the right to extract my keys themselves if they ever sign a backdoored bootloader (that can extract the now unencrypted keys from firmware).
For me the whole benefit of the fingerprint reader has been that it lets me select a very long boot passphrase, since I don't have to type it to unlock the phone. However, I'm now seriously considering removing the PIN from my lockscreen so I don't delude myself into storing anything of value on my phone.
Am I the only one super annoyed at these security developments?

Mine asks for my pin on first login.

Moogagot said:
Mine asks for my pin on first login.
Click to expand...
Click to collapse
Yes, but by the time it prompts for a PIN, it has clearly already decrypted the flash storage. So this means that if your bootloader is unlocked, someone could have messed with your system partition to bypass the lockscreen.

15xda said:
Yes, but by the time it prompts for a PIN, it has clearly already decrypted the flash storage. So this means that if your bootloader is unlocked, someone could have messed with your system partition to bypass the lockscreen.
Click to expand...
Click to collapse
That's not true. With device encrypted data and Direct Boot enabled, this restricted mode allows apps to perform limited actions and access non-personal data (i.e. specific system files), allowing it to boot up to the lock screen securely without any user interaction.
You have to enable it though, by going to developer options and selecting "covert to file encryption”. This WILL perform a factory reset though.

msaitta said:
That's not true. With device encrypted data and Direct Boot enabled, this restricted mode allows apps to perform limited actions and access non-personal data (i.e. specific system files), allowing it to boot up to the lock screen securely without any user interaction.
You have to enable it though, by going to developer options and selecting "covert to file encryption”. This WILL perform a factory reset though.
Click to expand...
Click to collapse
There is no "convert to file encryption" option in the developer options on the Pixel. Anyway, since the lock screen shows personal images and notifications and such, clearly a lot of data is available if someone decrypts the file system, even if there were an option to double-encrypt a few individual sensitive files. Anyway, what are the chances that every app developer encrypts every file I care about? This is why I want full device encryption, and I want full device encryption without storing my keys someplace where a backdoored bootloader can get at them.

15xda said:
Anyway, since the lock screen shows personal images and notifications and such, clearly a lot of data is available if someone decrypts the file system, even if there were an option to double-encrypt a few individual sensitive files.
Click to expand...
Click to collapse
Well, I stand partially corrected, actually. The device definitely seems to show some of my settings on reboot, like, for instance, volume. On the other hand, it can't receive VOIP calls (suggesting it doesn't have access to the SIP password I configured in the dialer), and incoming mobile calls don't show the contact name. So I guess it does offer some protection, but it's much harder to figure out what.

In case anyone lands on this thread, here is an explanation of what is happening on bootup:
https://developer.android.com/training/articles/direct-boot.html
The short answer is Pixel uses file-based-encryption now instead of disk-based encryption. I'm still not happy about this design because it somewhat reduces privacy and potentially complicates examining applications as root, but it's not as bad as I originally throught.

Regarding security & bootloader...

There are many sites selling Mix 3's some Chinese, some Global, some with locked bootloaders, and some with unlocked bootloaders, this thread is to help people "protect" the devices they have bought (or will buy).
It's through my understanding that the most "secure" way of protecting your phone & data from thief's is to have your bootloader locked, with no custom recovery, encryption on & usb debugging disabled right?
This is because with a unlocked bootloader, the thief has the ability to boot into TWRP (for example) & simply wipe your pin/password/lock off the phone completely, then just boot it up, factory reset it & sell it.
I know there is methods such as putting the phone in cold temperatures so you can retrieve the encryption keys from the RAM, but assuming the thief is just basic & what's to make some quick money off your phone...So...
What's the best way & most recommended thing to do with Xiaomi devices specifically, locked/unlocked, encrypted/not-encrypted, does it matter?, If not, why not?
Any help is appreciated! The more in-depth the better.

Even with a locked bootloader a thief can hold VolUp while booting, wipe phone and sell it. Wiping is possible in any case and thats not even the issue a stolen Phone is gone.
The issue are your data which can be stolen too when you have a unlocked bootloader. Simply boot to twrp connect usb and copy everything. But you can prevent that with encryption and enable "requires pattern to start". That way if your phone gets stolen the thief can still Install/use Twrp but he needs to enter a pattern to decrypt the storage. If he doesnt, twrp wont be able to read the partition and your data is safe. He can still wipe the Phone and sell it but you cant prevent that. I don't know if the pattern generates the encryption keys or retrieves them from somewhere but i'd assume it generates them, probably together with some device specific values, else that would be a flaw in my book. If someone could enlighten me here that'd be nice.
If your bootloader is locked he also can't access your data. Since stock recovers doesn't allow/support Usb-filetransfer. So a lockpattern is all you need there. Encryption shouldnt really matter against the normal thief.
I am going this way: Unlocked bootloader to get rid of Miui, Twrp to have a proper recovery menu, and encryption+pattern to save my data. Disable USB-Developer Options to prevent adb shenanigans.
But on the hand if you wan't to get really panariod a locked bootloader would be better since you still can read the system image from the phone from twrp, this means, and this is a easy way to do it, you could read it copy it to the pc and simply brutefroce the lockpattern. If you have the partitions you can simply try 3 patterns either it works or the phone locks itself up because you did 3 wrong. If it locks up you simply write the partitions back and try again. If you can do 3 in 30 seconds you are done in 45 days since there are only 390.000 different patterns on a 3x3 grid (which is what most people use since some Roms don't even allow for 4x4 or 5x5) but if you emulate it and can do 3 in 15 seconds you are down to 23 days. If you run it in 20 emulators you are done in 1 day. (That would be an awesome weekend project.) In emulation you could really optimize this since you can cut everything out what isn't needed for the attempt to encrypt the partition. you dont even need the screen to load, simply send the decryption module whatever the last module in the Numbers-from-touches-chain would have sent, everything that is loaded before the attempt to decrypt must be unencrypted therefore can be messed with, probably it's even universal across phones since that's a stock android thing. If it tries to write used attempts, save whatever what gets overwritten beforehand, let it write its thing, kill the process, revert changes and try again with the next set. Maybe you get it down to 3s or 4s for 3 attempts and boom you are at 6 hours to encrypt any android phone, no matter which version, with an unlocked bootloader which uses a 3x3 pattern. But your data would be really valueable to someone if they did this. You can't do that with a locked bootloader since you can't read the partitions or you could just use the 5x5 pattern, which you cant do on MIUI (i just tried and havent found where you could change it). But probably i have a giant oversight in there so this probably woudn't work
________________________________________________
On the other hand if you want to recover your phone you should make it as easy as possible to get the thief into your phone since you dont want them to run it off and wipe it. I DONT RECOMMEND THIS. But you could make a 2nd user who has no lock pattern on it. Concider your Data public at this point but while they are busy looking at your selfies you could use a app like prey to track the phone. But since Data are more important than a phone i'd never do or recommend that.

Or you could just buy a tin foil hat.

~phoeny~ said:
Even with a locked bootloader a thief can hold VolUp while booting, wipe phone and sell it. Wiping is possible in any case and thats not even the issue a stolen Phone is gone.
The issue are your data which can be stolen too when you have a unlocked bootloader. Simply boot to twrp connect usb and copy everything. But you can prevent that with encryption and enable "requires pattern to start". That way if your phone gets stolen the thief can still Install/use Twrp but he needs to enter a pattern to decrypt the storage. If he doesnt, twrp wont be able to read the partition and your data is safe. He can still wipe the Phone and sell it but you cant prevent that. I don't know if the pattern generates the encryption keys or retrieves them from somewhere but i'd assume it generates them, probably together with some device specific values, else that would be a flaw in my book. If someone could enlighten me here that'd be nice.
If your bootloader is locked he also can't access your data. Since stock recovers doesn't allow/support Usb-filetransfer. So a lockpattern is all you need there. Encryption shouldnt really matter against the normal thief.
I am going this way: Unlocked bootloader to get rid of Miui, Twrp to have a proper recovery menu, and encryption+pattern to save my data. Disable USB-Developer Options to prevent adb shenanigans.
But on the hand if you wan't to get really panariod a locked bootloader would be better since you still can read the system image from the phone from twrp, this means, and this is a easy way to do it, you could read it copy it to the pc and simply brutefroce the lockpattern. If you have the partitions you can simply try 3 patterns either it works or the phone locks itself up because you did 3 wrong. If it locks up you simply write the partitions back and try again. If you can do 3 in 30 seconds you are done in 45 days since there are only 390.000 different patterns on a 3x3 grid (which is what most people use since some Roms don't even allow for 4x4 or 5x5) but if you emulate it and can do 3 in 15 seconds you are down to 23 days. If you run it in 20 emulators you are done in 1 day. (That would be an awesome weekend project.) In emulation you could really optimize this since you can cut everything out what isn't needed for the attempt to encrypt the partition. you dont even need the screen to load, simply send the decryption module whatever the last module in the Numbers-from-touches-chain would have sent, everything that is loaded before the attempt to decrypt must be unencrypted therefore can be messed with, probably it's even universal across phones since that's a stock android thing. If it tries to write used attempts, save whatever what gets overwritten beforehand, let it write its thing, kill the process, revert changes and try again with the next set. Maybe you get it down to 3s or 4s for 3 attempts and boom you are at 6 hours to encrypt any android phone, no matter which version, with an unlocked bootloader which uses a 3x3 pattern. But your data would be really valueable to someone if they did this. You can't do that with a locked bootloader since you can't read the partitions or you could just use the 5x5 pattern, which you cant do on MIUI (i just tried and havent found where you could change it). But probably i have a giant oversight in there so this probably woudn't work
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On the other hand if you want to recover your phone you should make it as easy as possible to get the thief into your phone since you dont want them to run it off and wipe it. I DONT RECOMMEND THIS. But you could make a 2nd user who has no lock pattern on it. Concider your Data public at this point but while they are busy looking at your selfies you could use a app like prey to track the phone. But since Data are more important than a phone i'd never do or recommend that.
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Really appreciate the time you took to type out this post, thankyou.