As the capabilities of mobile devices grow, so do the prospective uses for real-world interactions. Using commonly carried devices, such as cell phones and PDAs, to assist in routine tasks, such as using vending machines or ATMs, is an emerging area of ubiquitous computing. This paper presents a secure method of using mobile devices to interact with real world objects. The model uses two dimensional colorized barcodes to easily establish a secure link between mobile devices and service points. The paper discusses the model, its security, and potential uses for common tasks.