Thinking Security: Stopping Next Year’s Hackers

Chapter 6. Cryptography and VPNs

He unlocked his desk, opened the drawer-safe, and withdrew the Executive’s Code Book, restricted to the executive heads of the firms listed quadruple A-1-* by Lloyds.

The Demolished Man—ALFRED BESTER

6.1 Cryptography, the Wonder Drug

Some years ago, shortly after Firewalls and Internet Security [1994] was first published, a friend who wasn’t fond of firewalls remarked that someday, he was going to write a book on how to do Internet security “correctly.” I asked him what that entailed; he replied, “Use Kerberos or other forms of cryptography.” Now, Kerberos [Bryant 1988; S. P. Miller et al. 1987; Neuman et al. 2005; Steiner, Neuman, and Schiller 1988] is a perfectly fine system; in Firewalls, we called it “extremely ...