Android player

I have the device MK802 this run android 4.0.3 and have an SD card I have place an SD card of 2GB. In this card there is an AVI file. This file has always the same name and it is the only into the sd card. What I want A) a program that read the sd sid make it Hex or octal So if somebody read it not recognize that it is the sid of the card and write it to the sd card into a file. This program will be at the sd card I run it once to make the file and then I will delete from the card. (there is an example at the web how to do this) b) A program that first read the sid of the card , compare it with the file that make with previous program and if it is ok then open the AVI file that the sd card will contain and play it. When the avi finish it will play it from the begine and so on. the avi file it has always the same name . The program B if the sid it isnot the same as into the file it will not play the avi. just exit. The program B will start automatic when the device strartup (power on) the programmer will give me 2 installations file one for the A program and one for the B program and the source code for both programms