• Journal of KIISE:Software and Applications
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• v.36 no.9
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• pp.767-776
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• 2009

A software birthmark is a set of characteristics that are extracted from a program itself to detect code theft. A dynamic API birthmark is extracted from the run-time API call sequences of a program. The dynamic Windows API birthmarks of Tamada et al. are extracted from API call sequences during the startup period of a program. Therefore. the dynamic birthmarks cannot reflect characteristics of main functions of the program. In this paper. we propose a functional unit birthmark(FDAPI) that is defined as API call sequences recorded during the execution of essential functions of a program. To find out that some functional units of a program are copied from an original program. two FDAPIs are extracted by executing the programs with the same input. The FDAPIs are compared using the semi-global alignment algorithm to compute a similarity between two programs. Programs with the same functionality are compared to show credibility of our birthmark. Binary executables that are compiled differently from the same source code are compared to prove resilience of our birthmark. The experimental result shows that our birthmark can detect module theft of software. to which the existing birthmarks of Tamada et al. cannot be applied.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.177-180
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• 2013

A software birthmark means inherent characteristics that can be used to identify a program. Because the software birthmark is difficult to remove by simple program transformation, it can be used to detect code theft. In this paper, we propose a birthmark technique based on API k-gram of Android applications. Android SDK provides various libraries that help programmers to develop application easily. In order to use Android SDK, we have to use API method calls. The API call instructions are hard to be replaced or removed, so they can be a inherent characteristics of an application. To show the effectiveness of the proposed birthmark, we compared it with previous birthmarks and evaluated it with open source applications. From the experiments, we verified that the credibility and resilience of our birthmark is higher than previous birthmarks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1297-1307
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• 2018

The rise of Online game ESD(Electronic Software Distribution) like Steam, the method of game piracy are more diversified. In Online Game ESD, Software DRM is applied to game because we have to play in offline situation, but it is easily bypassed due to low security level. In this study, we analyze crack files of pirated games to learn how to bypass Steam DRM and to establish countermeasures for based on API call birthmark. The generated birthmark showed more than 85% resilience in representing crack groups and 95% credibility in detecting cracked games. With this study, it is possible to enhance the security of the online game Electronic Software Distribution platform, and to provide a high level of game piracy protection for indie game developers, especially those who can not purchase Third Party DRM to protect their own games.