Reverse Engineering a Code without the Code

International audienceRetrieving assets inside a secure element is a challenging task.The most attractive assets are the cryptographic keys storedinto the Non Volatile Memory (NVM) area but also thealgorithms executed. Thus, the confidentiality of binary codeembedded in that device in the Read Only Memory (ROM)must be protected. Thanks to a previous attack we succeededin having access to a dump of NVM. We try here to to takeadvantage of the object oriented features of the platformto provide a means to speed up the reverse engineering ofthe dump. The idea here is to reverse engineer an algorithmwithout having access to to the code. We have only accessto the data. We use a specifically designed graphic tool toreason about the data such that we are able to understandthe principle of the algorithm. Then, we are able to bypassthe protection mechanism in order to get access to the binarycode