Bruce Schneier
termcryptographysecurity
The cryptographer and writer whose 1994 book Applied Cryptography taught a generation of programmers how ciphers work, who designed Blowfish and Twofish, and who then spent decades arguing that the hard problems in security are human and economic rather than mathematical.
He gave the field several of its most-used ideas: security theatre for measures that perform safety without providing it, the observation that security is a process and not a product, and Schneier's law - anyone can design a cipher they themselves cannot break. His newsletter has run since 1998 and remains one of the few places where the policy, economic and technical sides of the field are argued together.
Also known as: applied cryptography, schneier's law, security theater, blowfish