Today, public-key cryptography is everywhere, offering some measure of security for virtually all internet commerce transactions and secure shell connections. It's hard to imagine life without it, even though most people aren't aware of it.
Steven Levy's Crypto is a great book to explain it and how it all came about. In fact, I first read it almost twenty years ago when I was in high school, and just read it again the other day.
How did encryption in the digital age start out? How did public-key cryptography get invented? And how did public-key crypto get into the hands of pretty much everyone with a web browser all over the world despite the attempts of the U.S. government to control it? These questions are answered in Levy's book.
Crypto tells of the struggle between the early inventors of public-key technology and the U.S. government: the former attempting to release this new form of cryptography to the world both academically and commercially, and the latter attempting to stop them. Of course, the main nemesis is the NSA. It is fascinating to read how the government initially wanted to maintain strong public-key cryptography as a restricted technology, first to themselves and then to the American public. Everything from physical intimidation to export restrictions were used to slow the leak of this amazing technology to the world. Of course, the internet pretty much made the efforts of the NSA useless.
There is very little math in this book. No algorithms are explained, though a few scant details are provided. Readers wanting math should instead look at a textbook like Hoffstein's 'An Introduction to Mathematical Cryptography', Bruce Schneier's 'Applied Cryptography', or the source code to GnuPG. Instead, Levy writes about the individuals involved like Diffie, Hellman, Rivest, Shamir, Adleman, Zimmerman, and their winding quest for digital privacy.
Crypto is perfect for those wanting to know the history of public key cryptography and how it affected communications and the internet. Recommended.