Forging Low-Value Paper Certificates
Both Subway and Cold Stone Creamery have discontinued their frequent-purchaser programs because the paper documentation is too easy to forge. (The article says that forged Subway stamps are for sale on eBay.)
It used to be that the difficulty of counterfeiting paper was enough security for these sorts of low-value applications. Now that desktop publishing and printing is common, it’s not. Subway is implementing a system based on magnetic stripe cards instead. Anyone care to guess how long before that’s hacked?