The Code Book is a history of CryptoGraphy? and CryptoAnalysis? from the beginnings to CypherPunks and QuantumCryptography?. Singh found that British cryptographers came up with DiffieHellmanKeyExchange? and PublicKeyCryptography years before Diffie, Hellman and Merkle and Rivest, Shamir and Adleman came up with them, but as they were controlled by security concerns, they could not announce them.
The book reminded me of how much of an understanding I had of PublicKeyCryptography and related technologies, and, looking from way back, how simple it all seems.