Schneier on Security
A blog covering security and security technology.
November 9, 2010
Kahn, Diffie, Clark, and Me at Bletchley Park
Talk #1: "The Art of Forensic Warfare," Andy Clark. Riffing on Sun Tzu's The Art of War, Clark discussed the war -- the back and forth -- between cyber attackers and cyber forensics. This isn't to say that we're at war, but today's attacker tactics are increasingly sophisticated and warlike. Additionally, the pace is greater, the scale of impact is greater, and the subjects of attack are broader. To defend ourselves, we need to be equally sophisticated and -- possibly -- more warlike.
Clark drew parallels from some of the chapters of Sun Tzu's book combined with examples of the work at Bletchley Park. Laying plans: when faced with an attacker -- especially one of unknown capabilities, tactics, and motives -- it's important to both plan ahead and plan for the unexpected. Attack by stratagem: increasingly, attackers are employing complex and long-term strategies; defenders need to do the same. Energy: attacks increasingly start off simple and get more complex over time; while it's easier to defect primary attacks, secondary techniques tend to be more subtle and harder to detect. Terrain: modern attacks take place across a very broad range of terrain, including hardware, OSs, networks, communication protocols, and applications. The business environment under attack is another example of terrain, equally complex. The use of spies: not only human spies, but also keyloggers and other embedded eavesdropping malware. There's a great World War II double-agent story about Eddie Chapman, codenamed ZIGZAG.
Talk #2: "How the Allies Suppressed the Second Greatest Secret of World War II," David Kahn. This talk is from Kahn's article of the same name, published in the Oct 2010 issue of The Journal of Military History. The greatest secret of World War II was the atom bomb; the second greatest secret was that the Allies were reading the German codes. But while there was a lot of public information in the years after World War II about Japanese codebreaking and its value, there was almost nothing about German codebreaking. Kahn discussed how this information was suppressed, and how historians writing World War II histories never figured it out. No one imagined as large and complex an operation as Bletchley Park; it was the first time in history that something like this had ever happened. Most of Kahn's time was spent in a very interesting Q&A about the history of Bletchley Park and World War II codebreaking.
Talk #3: "DNSSec, A System for Improving Security of the Internet Domain Name System," Whitfield Diffie. Whit talked about three watersheds in modern communications security. The first was the invention of the radio. Pre-radio, the most common communications security device was the code book. This was no longer enough when radio caused the amount of communications to explode. In response, inventors took the research in Vigenère ciphers and automated them. This automation led to an explosion of designs and an enormous increase in complexity -- and the rise of modern cryptography.
The second watershed was shared computing. Before the 1960s, the security of computers was the physical security of computer rooms. Timesharing changed that. The result was computer security, a much harder problem than cryptography. Computer security is primarily the problem of writing good code. But writing good code is hard and expensive, so functional computer security is primarily the problem of dealing with code that isn't good. Networking -- and the Internet -- isn't just an expansion of computing capacity. The real difference is how cheap it is to set up communications connections. Setting up these connections requires naming: both IP addresses and domain names. Security, of course, is essential for this all to work; DNSSec is a critical part of that.
The third watershed is cloud computing, or whatever you want to call the general trend of outsourcing computation. Google is a good example. Every organization uses Google search all the time, which probably makes it the most valuable intelligence stream on the planet. How can you protect yourself? You can't, just as you can't whenever you hand over your data for storage or processing -- you just have to trust your outsourcer. There are two solutions. The first is legal: an enforceable contract that protects you and your data. The second is technical, but mostly theoretical: homomorphic encryption that allows you to outsource computation of data without having to trust that outsourcer.
Diffie's final point is that we're entering an era of unprecedented surveillance possibilities. It doesn't matter if people encrypt their communications, or if they encrypt their data in storage. As long as they have to give their data to other people for processing, it will be possible to eavesdrop on. Of course the methods will change, but the result will be an enormous trove of information about everybody.
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