Given the high cost of producing software, development of technology for prevention of software piracy is important for the software industry. In this paper we present a novel approach for preventing the creation of unauthorized copies of software. Our approach splits software modules into open and hidden components. The open components are installed (executed) on an unsecure machine while the hidden components are installed (executed) on a secure machine. We assume that while open components can be stolen, to obtain a fully functioning copy of the software, the hidden components must be recovered. We describe an algorithm that constructs hidden components by slicing the original software components. We argue that recovery of hidden components constructed through slicing, in order to obtain a fully functioning copy of the software, is a complex task. We further develop security analysis to capture the complexity of recovering hidden components. Finally we apply our technique to several large Java programs to study the complexity of recovering constructed hidden components and to measure the runtime overhead introduced by splitting of software into open and hidden components.