Question $5(5$ points$)$

When shopping at Costco, after you've selected your purchases you take your cart full of goods to one of the registers. The check$-$out clerk scans your goods, totals what you owe, and upon receiving payment from you gives you an itemized receipt. However, you can't then simply exit the building with your goods. At the exit you're required to go by a staff member who inspects your receipt. If the receipt looks okay $($appears to match the number and types of items in your cart$),$ the staff member draws a line with a permanent marker down the receipt and hands it back to you. At this point, you can exit the building and take the goods to your car.

Identify two security principles illustrated by Costco's approach. For each, describe in a single sentence what aspect of Costco's approach reflects the principle.

Identify an attack that Costco seeks to prevent by having the staff member draw the line down your receipt.