Thinking Security: Stopping Next Year’s Hackers

Chapter 8. PKI: Public Key Infrastructures

“I see a complex netting of obligations, but within it there is a pyramid of power. No one is truly independent, but as you near the top of the pyramid power increases enormously; however, it is seldom used to its fullest. There are lines of obligation that reach in all directions, upwards, downwards, sideways in a totally alien manner.”

Charlie in The Mote in God’s Eye—LARRY NIVEN AND JERRY POURNELLE

8.1 What’s a Certificate?

Public key cryptography, as originally described by Diffie and Hellman [1976], seemed simple. Someone uses your public key to encrypt a message to you; you use your private key to decrypt it. However, Diffie and Hellman paid little attention to how communicants acquire each others’ ...