Using Samsung S-Pen in Canvas

I am working on a web application where the user should be abled to sign a document on a tablet. We use the Galaxy Tab 12.2 because the S-Pen has the desired precision. The canvas where i draw on uses listens to the touch events to draw on the canvas.

        canvas.addEventListener('touchstart', handleStart);
        canvas.addEventListener('touchmove' , handleMove);

The problem here is, that if the user touches the canvas with his fingers, the canvas will draw lines there.

Is there a way to differentiate between S-Pen events and 'normal' touch events?

I know that on the Surface Pro 3 with Internet Expoler I can handle Pen input different from finger input.