—A software birthmark is an inherent characteristic of a program that can be used to identify that program. By comparing the birthmarks of two programs, it is possible to infer if one program is a copy of another. In this paper, we propose a static birthmark based on the control flow edges in Java programs. Control flow edges can represent possible behaviors in program execution. Thus, a set of the control flow edges of a program can be used as a birthmark for that program. The similarity between two programs can then be calculated by finding pairs of similar behaviors of the control flow edges in the two birthmarks. The proposed birthmark is evaluated and compared with previous approaches in terms of credibility and resilience. Experimental results show that the proposed birthmark is more reliable than previous methods for detecting programs that are suspected to be copied. Keywords-software birthmark; software security; software copyright; program analysis;