Peter is writing about this excerpt from The Code Book . A variation on the Trojan horse is a brand-new piece of encryption software that seems secure, but which actually contains a backdoor , something that allows its designers to decrypt everybody's messages. In 1998, a report by Wayne Madsen revealed that the Swiss cryptographic company Crypto AG had built backdoors into some of its products, and had provided the U.S. Government with details of how to exploit these backdoors. As a result, America was able to read the communications of several countries. Which of Peter’s lines shows that he is using personal experience to understand the reading?