In order to use resources of a computer, malware has to know the interfaces provided by the operating system. If we make these critical interfaces unique by diversifying the operating system and user applications, a piece of malware can no longer successfully interact with its environment. Diversification can be considered as a computer-specific secret. This paper discusses how this API diversification could be performed. We also study how much work would be needed to diversify the Linux kernel in order to hide the system call interface from malware.