Of the texts Satoshi extracted 50 most frequently used words. They broke all his texts into 5000 verbal constructions and analyzed the frequency of using these 50 words. As a result, they received a unique 50-number identifier for each design, then put each digit in 50-dimensional space and flattened into a plane using the analysis of the main components. As a result, the NSA received the "handwriting" of Satoshi, which could easily be identified in any text.
Then they took the database of texts collected from all over the Internet - from PRISM (court approved access to Google and Yahoo users' accounts) and MUSCULAR (NSA copies data streams over fiber optic cables that transmit information from Google, Yahoo, Amazon and Facebook data centers). To compare the "handwriting" of billions of people around the world with the "handwriting" of Satoshi. Less than a month of searching for the NSA found a coincidence