Cryptonomicon by Neal Stephenson.
Here is the description from Amazon:
In 1942, Lawrence Pritchard Waterhouse—mathematical genius and young
Captain in the U.S. Navy—is assigned to detachment 2702. It is an outfit
so secret that only a handful of people know it exists, and some of
those people have names like Churchill and Roosevelt. The mission of
Waterhouse and Detachment 2702—commanded by Marine Raider Bobby
Shaftoe-is to keep the Nazis ignorant of the fact that Allied
Intelligence has cracked the enemy's fabled Enigma code. It is a game, a
cryptographic chess match between Waterhouse and his German
counterpart, translated into action by the gung-ho Shaftoe and his
Fast-forward to the present, where Waterhouse's
crypto-hacker grandson, Randy, is attempting to create a "data haven" in
Southeast Asia—a place where encrypted data can be stored and exchanged
free of repression and scrutiny. As governments and multinationals
attack the endeavor, Randy joins forces with Shaftoe's tough-as-nails
granddaughter, Amy, to secretly salvage a sunken Nazi submarine that
holds the key to keeping the dream of a data haven afloat. But soon
their scheme brings to light a massive conspiracy with its roots in
Detachment 2702 linked to an unbreakable Nazi code called Arethusa. And
it will represent the path to unimaginable riches and a future of
personal and digital liberty...or to universal totalitarianism reborn.
A breathtaking tour de force, and Neal Stephenson's most accomplished and affecting work to date, Cryptonomicon is
profound and prophetic, hypnotic and hyper-driven, as it leaps forward
and back between World War II and the World Wide Web, hinting all the
while at a dark day-after-tomorrow. It is a work of great art, thought
and creative daring; the product of a truly iconoclastic imagination
working with white-hot intensity.
--This is another classic I am revisiting. This book is 1200 pages long. So I doubt I will finish it this week.