I liked Cryptonomicon, but more for the WWII side of the story. If you liked that part, check out Colossus by Jack Copeland. The Randy Waterhouse side of the story actually reminded me a lot of Digital Fortress by Dan Brown. Say what you will about Dan Brown, but I thought Digital Fortress was great.
Are you being serious about Digital Fortress? Digital Fortress is infamous for its technological and geographical inaccuracies. I found it good for a chuckle, but I wouldn't really consider it hacker fiction, unless we're talking about Hollywood's idea of a hacker.
