Just Finished: Crypto by Steven Levy
Crypto was an examination of consumer cryptography from its genesis in the Sixties to the present. This is mostly the story of Public Key cryptography, in which a user generates two keys. As one might guess, the public key is distributed to the public, and the private key is kept secret. Any message encrypted with the public key can be decrypted by the private key and vice-versa. Such messages can also include keys for traditional Symmetric Key cryptography, which is faster but requires that both parties share the same secret key. Another use of the public key system is to digitally sign plaintext messages. This is usually done by passing the message through a mathematical hash function, which produces a very long number which can be though of as the message’s fingerprint. Encrypting the hash with one’s private key allows anyone with access to the corresponding public key to verify the integrity of the message.
This technique was actually invented about thirty years ago, and began to appear in commercial products in the Eighties. But it wasn’t until the dot-com era of the Nineties that it gained real recognition, for this is what enabled secure e-commerce over the Internet.
The book was well written, but I felt that it lacked the real historical revelation that I experienced when I read the author’s other book, Hackers. Still, it was informative and interesting.