In an interview on Tuesday with the Wall Street Journal, former NSA chief and Booz Allen Vice Chairman Mike McConnell explained how Edward Snowden gained access to all of the files that he’s been leaking. If McConnell is to be believed, Snowden was hired in the first place after using a trick he probably learned in high school: He “stole” an NSA admittance test with the answers, and used it to ace the test.

According to McConnell, Snowden initially worked at the NSA as a security guard, then in the IT department, which sent him overseas. He left the NSA to work in another company in Japan. Eventually, Snowden wanted to rejoin the NSA. At this point, McConnell claims he broke into the NSA to steal the test and pass it. After the test, “he walked in and said you should hire me because I scored high on the test,” McConnell said.

After the NSA offered him a position, he turned it down because he thought he should have a higher-ranking position. Instead, he went to work at national security contractor Booz Allen in early 2013. Booz Allen hired Snowden because the NSA had already vetted and approved him.

At Booz Allen, he was given a high level of access. The NSA has four levels of access: Basic administrative access, then access to secret information that doesn’t reveal sources, and then finally two more levels of access that give people knowledge of “how we do what we do,” according to McConnell. Snowden had “limited access” to the third level and “almost no access” to the fourth level, McConnell said. Overall, this gave Snowden access to 1.7 or 1.8 million documents.

Unsurprisingly, McConnell isn’t too pleased with Snowden’s actions. Snowden “has compromised more capability than any spy in U.S. history. And this will have impact on our ability to do our mission for the next 20 to 30 years,” he said.