read like the mathematics background chapter of a cryptography book A lot of maths-related books, especially ones intended as textbooks will read like that in

read like the mathematics background chapter of a cryptography book A lot of maths-related books, especially ones intended as textbooks will read like that in part because they aren't kidding about the 'abstract' in the title - they're trying to teach/re-summarize key concepts of mathematical abstraction. It's a good and true thing to notice.