1. Code Protection In Android
Arman Kabiri
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2. • Introduction
• Android Architecture
• Reverse Engineering
• Code Obfuscation
• Conclusion
Index
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3. • what is Android Platform
• what need to protect Code
• Reverse Engineering
• Code Obfuscation
Introduction
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4. Android Architecture
• apps are written in java
• java code transfer into bytecode
• deployed as file called APK (zip compressed file)
• dex file containing code in form of Dalvik bytecode
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5. DalvikVirtual Machine
• Dvm will execute dalvik bytecode on device
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6. Reverse Engineering
• process of gaining information about a program
• its implementation
• its meta data
• ideal result is to recover correct java source code
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7. Disassembler
is a tool which gets bytecode as input and produce
equivalent mnemonics
most of the reverse engineering process are based on this
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8. Code Obfuscation
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9. Obfuscation Goals
• protect apps against software piracy
• guard intellectual property
• guard implemented sensitive algorithm
• protect app from trojanized version publication
• protect malware apps from antivirus detection
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10. ObfuscationTechniques
• well-known techniques under X86
• makes reverse engineering harder and more time consumer
• apps behavior must not be altered
• each technique target specific reverse engineering
• drawback: impact on execution speed
• popular techniques has mentioned in continue…
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11. Identifier mangling
identifier : name for packages , classes , methods , fields
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12. String Obfuscation
• using encryption algorithm such as AES
• the original content must be available
• feasible with function F which is invertible
• can be defeated by dynamic analysis
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13. Dynamic Code Loading
• not only encrypting data but also code
• feasible with encryption stub and decryption stub
• better implementation in native code
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14. Junkbytes
• used to confuse disassemblers
• inserting junkbytes within the bytecode
• junkbytes must never be executed
• can defeats many disassemblers tools
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15. Conclusion
• code protection is an interesting field of research
• dalvik bytecode , main interest for this topic
• Still there are problems with transforming d_bytecode into
mnemonics correctly
• efficient obfuscation approaches are hardware dependent
and its such a ideal future work
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16. Any Question …?
Thanks for your attention
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