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[APP][ICS] EncPassChanger -- set different device encryption and lock screen password

OP Kibab

26th June 2012, 09:17 AM   |  #1  
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Android 3+ has a nice feature -- device encryption. You can encrypt the contents of your device with a password, and after that this password must be entered during device boot, otherwise the data is permanently lost.
The bad thing is that this password is set to the screen lock PIN / password. So you either set a short password or PIN, that you can enter quickly each time you unlock your phone from sleep (but this provides weak encryption), or set a long password and have to type it 20-30 times during the day.

This stupid behavior may be fixed easily. Android provides command-line tool called 'vdc', an interface to Android Volume Manager. As written in "Notes on the implementation of encryption in Android 3.0" [1], it has a command 'cryptfs changepw', that allows changing encryption password. Of course this command must be executed as root.
vdc has some other commands related to encryption, one of them is 'cryptfs verifypw', that allows to validate the supplied password.

I'm currently writing an application that will assist user with changing encryption password. This is my first public application for Android. You can find a source code on GitHub [2]. It is very simple, but maybe android gurus here may find what to make better.

Comments and pull requests are welcome :)
Thanks!

[1] http source.android.com/tech/encryption/android_crypto_implementation.html
[2] https github.com/kibab/encpasschanger
Attached Files
File Type: apk EncPassChanger.apk - [Click for QR Code] (26.1 KB, 562 views)
Last edited by Kibab; 29th June 2012 at 10:15 PM. Reason: Added APK
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29th June 2012, 10:16 PM   |  #2  
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Updated 30.06.2012: Added APK file!
4th July 2012, 05:50 AM   |  #3  
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Quote:
Originally Posted by Kibab

Android 3+ has a nice feature -- device encryption. You can encrypt the contents of your device with a password, and after that this password must be entered during device boot, otherwise the data is permanently lost.
The bad thing is that this password is set to the screen lock PIN / password. So you either set a short password or PIN, that you can enter quickly each time you unlock your phone from sleep (but this provides weak encryption), or set a long password and have to type it 20-30 times during the day.

This stupid behavior may be fixed easily. Android provides command-line tool called 'vdc', an interface to Android Volume Manager. As written in "Notes on the implementation of encryption in Android 3.0" [1], it has a command 'cryptfs changepw', that allows changing encryption password. Of course this command must be executed as root.
vdc has some other commands related to encryption, one of them is 'cryptfs verifypw', that allows to validate the supplied password.

I'm currently writing an application that will assist user with changing encryption password. This is my first public application for Android. You can find a source code on GitHub [2]. It is very simple, but maybe android gurus here may find what to make better.

Comments and pull requests are welcome :)
Thanks!

[1] http source.android.com/tech/encryption/android_crypto_implementation.html
[2] https github.com/kibab/encpasschanger

Sorry im noob
What will change visualy?
Or screenshot?

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11th July 2012, 07:50 AM   |  #4  
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Thank you for this. I wanted a more simple password for the unlock, but a longer more complicated password for the decryption. You should put it on the market and charge $.99USD (or equivalent in your currency) as it's quite useful. I'd buy it
17th July 2012, 08:40 PM   |  #5  
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Thank you!
Actually I have registered myself as Google Play Developer, now I'm waiting for approval. As soon as my registration is approved, I will update this thread :)
Although I'm going to make a free and donate versions, because I believe that will help to make Android better, and people who want to say "Thank you" will buy Donate version anyway
18th July 2012, 08:35 AM   |  #6  
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Smile
Quote:
Originally Posted by uDroid

Sorry im noob
What will change visualy?
Or screenshot?

Sent from my LT26i using XDA Premium HD app

Nothing will change visually, hence no screenshot. What's important is that you may set strong password for decrypting the internal storage, but keep using simple password (or PIN) to unlock the screen.

P.S. I have verified that my app works on Jelly Bean too.
18th August 2012, 11:04 AM   |  #7  
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I have finally published an application on Google Play! Currently there is a free version, Donate version will come a bit later
The link is: https:// play.google.com/store/apps/details?id=com.kibab.android.EncPassChanger

Enjoy!
21st August 2012, 08:31 AM   |  #8  
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Thanks for that app, that is also what annoyed me
21st August 2012, 09:48 AM   |  #9  
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Thanks for this. I've been trying to work out why encryption wont work on any ROM on my HOX (dies with unable to get size of block device cryptfs), and you have given me a good lead to investigate with vdc. Information on encryption in android is sparse, and almost all threads here on XDA get no replies.

Thanks again.
21st August 2012, 12:21 PM   |  #10  
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I've been tempted to use device encryption recently, but there is a distinct lack of information about it, particularly on custom ROMs...

Might need to give it a go, just the lack of backup abilities might be an issue...

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