-science fiction, young adult

-main character was a male

-someone had made some kind of system where everyone had their own personal code - could be a bank password, savings code, etc. - but it was extremely private and considered unhackable. I think it was based on polynomials or factorials

-The conflict is that someone figures out how to hack everyone’s password, data is exposed

-main character has some kind of relationship to either the person that created the code or the person that hacked it. I think there’s a rivalry between the main character and another male

-there’s a really big twist in the middle of the book!

-might turn into a heist book? but also maybe not

-I *think* the original hardcover is blue/green, has overlayed code in the background, one modern-looking symbol. Possibly a key

-read in 2013/2014, and I had at least 2 books in the series out at the time, I’m only describing the first one. I was in 8th grade - 12 or 13 at the time. The book was age-appropriate