What is a Side Channel Attack

Side channel attacks use physical properties to discern digital information. They exploit design flaws in the actual hardware or flaws in the design on the algorithm.​

What are some methods of side channel attacks?

• Timing - Does the system take longer to respond on a correct password then a bad password
• Temperature - Does the chip react adversely to high temperature 
• Electromagnetic Interference- What EMI is being given off and what can we discern from it

How can I be safe?

The only thing you can do is to keep people from getting physical access. Other than that there is no real way you can prevent this. These attacks exploit the way the system or algorithm was designed. Since you cant research every little chip and every line of code on your computer all you can do is to keep it out of the hands of others.