Digital signature control for asp.net

Question

I want to add signature facility where user can draw his sing using mouse and after that sign should be stored in Image file. I searched this in google and I find lots of third party controls, or some said it can be accomplished using silverlight or flash or html5. But is it possible to create my own control using asp.net or javascript or ajax or jquery. Can I use System.Graphics class to draw lines on mouse click event to draw the line and after that stored in image. I don't want to other third party control and not able to use flash. If it is easy using silverlight or html5 then I want to show some sample code. Please guide me.