The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • My Flickr Stream

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,617 other followers

Archive for the ‘Android’ Category

Some links on keystore, encryption and decryption on Android

Posted by jpluimers on 2019/02/06

For my link archive:

 

Basically:

  • storing encrypted data plus IV in preferences is OK
  • store the symmetric encryption key (for instance an AES one) in the keystore for the application
  • likely a salt is also needed, then store the salt with the IV and encrypted data

–jeroen

Presumptions:

  • The keystore of a specific application UUID is only accessible by only that application UUID when the device has been unlocked by the user
  • The keystore saves credentials in a secure way
  • It is OK to save both the encrypted data and associated IV

Approach (plain data is “hashed application PIN”, encrypted data is “encrypted hashed application PIN”:

  1. store a symmetric AES key in the application key store
  2. after entering application PIN:
    1. hash the application PIN
    2. use the hashed application PIN to to enter the application
    3. from the keystore, obtain the symmetric AES key
    4. create a cipher based on the AES key
    5. use the cipher to obtain an IV, and to encrypt the hashed application PIN
    6. store the encrypted hashed application PIN and IV both in the application preferences
  3. when needing to enter the application, present the user to either enter the application PIN again or proof that they can pass the device unlock sequence (using an unlock activity)
    1. if the user provided the application PIN, then:
      1. hash the application PIN
      2. try to enter the application with the hashed application PIN
    2. proved the device unlock, then:
      1. from the preferences, obtain the IV and encrypted hashed application PIN
      2. from the keystore, obtain the symmetric AES key
      3. create a cipher based on the AES key
      4. decrypt the encrypted hashed application PIN using the cipher and the IV into the hashed application PIN
      5. try to enter the application with the hashed application PIN

Posted in Android, Development, Mobile Development, Software Development | Leave a Comment »

Quick Intro Into Actions on Google | Grokking Android

Posted by jpluimers on 2019/01/30

Hopefully by now the Google Assistant and Google Home have made their way into the Dutch language. If so, then it’s time for me

[WayBackQuick Intro Into Actions on Google | Grokking Android: Find out which options exist to develop apps for the Google Assistant with Actions on Google and to bring the Assistant to devices with the Assistant SDK.

–jeroen

 

Posted in Android, Android Devices, Development, Google, Google AI, Google Assistant, GoogleHome, Mobile Development, Software Development | Leave a Comment »

Don’t forget your padding… playing with the APK format of a sample “Hello world” Android app

Posted by jpluimers on 2019/01/23

Don’t forget your padding: Hello,I’m playing with the APK format of a sample “Hello world” Android application.my (first) goal is to be able to rebuild an APK from a unzipped one… – Paul TOTH – Google+

References: RSA Algorithm

–jeroen

Posted in Android, Development, Encryption, Mobile Development, Power User, Security, Software Development | Leave a Comment »

Vysor standalone downloads

Posted by jpluimers on 2018/09/19

I wrote about Vysor before, but totally forgot to mention that for like 2 years there have been (initially beta) standalone versions of Vysor based on the Electron framework that is also used by the Atom.io editor and Visual Studio code.

So here they are (:

Over time, these have been updated with new versions.

Web site source: https://github.com/koush/vysor.io

–jeroen

History:

Related:

Posted in Android, Android Devices, Development, Mobile Development, Power User, Vysor | Leave a Comment »

Improve Android and iOS debug compilation speed – grijjy blog – Set the Debug information option to Limited Debug information

Posted by jpluimers on 2018/04/12

If you develop mobile apps with Delphi, you know it: compiling for Android and iOS is sloooooooooooooow, especially for debug builds. This little tip makes compiling Debug builds much faster……

Set the Debug information option to Limited Debug information

When I read a thing like that, I always think “how come I never thought about that before?” Well done Erik!

[WayBackImprove Android and iOS debug compilation speed – grijjy blog

via: [WayBack] Here’s a quick tip to improve the compilation speed of debug builds for iOS and Android… – Erik van Bilsen – Google+

–jeroen

Posted in Android, Delphi, Development, iOS Development, Mobile Development, Software Development | Leave a Comment »

 
%d bloggers like this: