Embedded Linux Conference + Android Builders Summit

Even though Android has the spotlight of mobile research, little has been said about its unique file format, the Dalvik Executable. DEX, as it is known, is a file format developed to encapsulate the bytecode of Android applications. It is a unique combination of concepts borrowed from other file formats, such as DWARF debug format, into a highly optimized executable format with a small memory footprint. The contents of this talk are based on the development of the Dexterity library, an open source library for DEX instrumentation. It will describe the internals of the Dalvik Executable as well as techniques for direct manipulation of its binaries, which is a requirement for analysis, optimization, obfuscation and many other applications. It will also talk about the main limitations of DEX and the key concepts needed for porting the format to 64bit architectures.