proguard - Obfuscate Android bytecode -

all, i'm trying use proguard obfuscate .apk file , seems not working. proguard works java bytecode, use dex2jar convert apk file jar file, use proguard obfuscate it, , repackage output jar apk. resulting apk seems problematic. got lot of error could not read file: expected chunk of type 0x80003, read 0x6d783f3c. there anyway can obfuscate android bytecode directly on .apk instead of source code? please help.

thanks!

you need use proguard proper configuration android. there predefined setting gradle build file (when using android studio)

android {  ...   buildtypes {     release {         minifyenabled true         proguardfiles getdefaultproguardfile('proguard-android.txt'),         'proguard-rules.pro'     }   } } 

source: http://developer.android.com/tools/help/proguard.html