Recently I had the task to ensure a mock shopping cart app on the web was working correctly. I decided to play with the darn thing to gain insight on all the things I needed to check. At first glance all seemed well. I added items to my cart. The total amount at the bottom seemed to be incrementing correctly. Then I found some disturbing behavior.
When I removed an item from my cart, it did not always accurately decrease my total price. It did work sometimes. But it did not work most of the time. There was also some weird errors when I removed the last item in the cart. I wanted to go further. I wanted to assist the developer in figuring out what was going wrong.
A Little Bit of Crypto - I have been trying to figure out to "collision resistant" some of these standard hash functions are. It is a tough concept to get my head around. I figure...