Given this background, it's intriguing to find Schneier, in recent issues of Crypto-gram, expounding on the limitations of math-based cryptography. "In my book, I wrote that we needed to protect ourselves not with laws, but with mathematics," he says. "It was interesting, but incredibly naive." Now Schneier, the inventor of the popular encryption algorithm called "Blowfish," believes that such schemes will never be sufficient. Instead, his efforts focus on dealing with complexity, which he sees as the root cause of security vulnerabilities.