A dynamic password based security system

The basic block diagram of setup is as below:

So this contains two parts, one is authentication and second is security.

Here is the flow chart of how security part works.

How to detect a fast motion,  how to send an SMS in a C program are already explained in the given links.

Now, the question is how to do these things simultaneously? Well, the answer obviously is Multi-threading. There can be one main thread that continuously checks for a fast motion. There could be another thread that sends the alert text SMS, and one more which will transfer image from our machine to a central system. Threading in C can be easily understood by googling a bit. Here is the link to the source code.

Before running this code, what you will need to do is generate an ssh-key and copy it in the central machines. That way you will be allowed to scp command (copy over ssh) without typing the ssh password. Here is a link that explains it.

Second part is Authentication:

Well now, generating a passcode is like generating a random number, which explained here. Sending the generated passcode via SMS is explained here.  But, there is whole lot of other stuff here, for example starting a timer, getting the passcode “secretly”, stop getting the data after timer expires. All these processes are drawn in diagram below.

So the functions:

1.       Starting a timer, which is timer interrupt in Linux kernel, can be seen here

2.       Now, to get passcode “secretly”, you can see here

3.       To kill an application, you need to run command “kill process_id”( which is done after the timer expires)

Now all these things, are included in a git-hub project here.

Thanks for reading, comment are most welcome.