What is the name of this type of bolt for the front crank on my bike? I recently had to take the front gear off of my bike and had some difficulty undoing the bolts. Because of their poor condition, I have decided to replace them. However, I have no idea what they are called. I've included a couple photos that show the bolts themselves and the holes they are meant to fill. I had to saw the end of one of them off to get it out, and the Allen key holes are circular, so really they do need replacing.
They're called simply chainring bolts. The tool to hold the other part while tightening is chainring bolt wrench.