**Once upon a time**

I had an early gift for mathematics and understanding three-dimensional form. When I was 16 or so, I helped my dad understand and then solve specific problems in

**spherical trigonometry**. It eventually became clear to me that I was helping him verify circuitry specifically designed for suborbital mechanics: inertial guidance around the earth. Later I found out in those years he was working on the Poseidon SLBM for Lockheed, so, without completely understanding it, I was actually working on weaponized computation.

This is the period of my life where I learned about the

**geoid**: the specific shape of the earth, largely an oblate ellipsoid. The exact shape depends upon gravitation, and thus mass concentrations (

**mascons**). Lately the gravitational envelope of the moon caused by mascons has been an issue for the Lunar Orbiters.

At that point in history,

**rocket science**was quite detailed and contained several specialized areas of knowledge. Many of which were helped by increasingly complex calculations. But there have been other fields that couldn't have advanced, where specific problems couldn't be solved, without the advances in computation. Ironically, some basic advances in computation we enjoy today owe these problems for their very existence. Consider this amazing article that details the first 25 years or so of the supercomputing initiatives at Lawrence Livermore National Laboratory.

**Bombs**

Throughout our computing history, computation has been harnessed to aid our defense by helping us create ever more powerful weapons. During the

**Manhattan Project**at Los Alamos, Stanley Frankel and Eldred Nelson organized the

**T5 hand-computing group**, a calculator farm populated with Marchant, Friden, and Monroe calculators and the wives of the physicists entering data on them. This group was arranged into an array to provide one of the first parallel computation designs, using Frankel's elegant breakdown of the computation into simpler, more robust calculations. Richard Feynman, a future Nobel prize winner, actually

*learned to fix the mechanical calculators*so the computation could go on unabated by the huge time-sync of having to send them back to the factory for repair.

I was fortunate enough to be able to talk with Feynman when I was at Caltech, and we discussed group T-5, quantum theory, and how my old friend Derrick Lehmer was blacklisted for having a Russian wife. He told me that Stanley Frankel was also blacklisted. Also, I found 20-digit Friden calculators particularly useful for my computational purposes when I was a junior in High School.

The hunger for computation continued when Edward Teller began his work on the Super, a bomb organized around thermonuclear fusion. This lead John von Neumann, when he became aware of the ENIAC project, to suggest that the complex computations required to properly understand thermonuclear fusion could be carried out on one of the world's first electronic computers.

**Codebreaking**

In the history of warfare, codebreaking has proven itself to be of primary strategic importance. It turns out that this problem is perfectly suited to solution using computers.

One of the most important first steps in this area was taken at

**Bletchley Park**in Britain during World War II. There, in 1939, Alan Turing constructed the Bombe. This was an early electromechanical computer and it was specifically designed to break the cipher and daily settings used in the German Enigma machine.

This effort required huge amounts of work and resulted in the discovery of several key strategic bits of information that turned the tide of the war against the Nazis.

The mathematical analysis of codes and encoded information is actually the science of

**decryption**. The work on this is never-ending. At the

**National Security Agency**'s Multiprogram Research Facility in Oak Ridge, Tennessee, hundreds of scientists and mathematicians work to construct faster and faster computers for cryptanalytic analysis. And of course there are other special projects.

That seems like it would be an interesting place to work. Except there's no sign on the door. Well, this is to be expected since security is literally their middle name!

And the NSA's passion for modeling people has recently been highlighted by Edward Snowden's leaks of a slide set concerning the NSA's metadata-colecting priorities. And those slides could look so much better!

**Passwords**

In the modern day, hackers have become a huge problem for national and corporate security. This is partly because, recently, many advances in password cracking have occurred.

The first and most important advance was when RockYou.com was hacked with an SQL injection attack and 32 million (14.3 million unique) passwords were posted online. With a corpus like this, password crackers suddenly were able to substantially hone their playbooks to target the keyspaces that contain the most likely passwords.

A keyspace can be something like "a series of up to 8 digits" or "a word of up to seven characters in length followed by some digits" or even "a capitalized word from the dictionary with stylish letter substitutions". It was surprising how many of the RockYou password list could be compressed into keyspaces that restricted the search space considerably. And that made it possible to crack passwords

*much*faster.

Popular fads like the stylish substitution of "i" by "1" or "e" by "3" were revealed to be exceptionally common.

Another advance in password cracking comes because passwords are usually not sent in plaintext form. Instead, a

**hashing function**is used to obfuscate them. Perhaps they are

*only*stored in hashed form. So, in 1980 a clever computer security professor named Martin Hellman published a technique that vastly sped up the process of password cracking. All you need to do is keep a table of the hash codes around for a keyspace. Then, when you get the hash code, you just look it up in the table.

But the advent of super-fast computers means that it is possible to compute billions of cryptographic hashes per second, allowing the password cracker to iterate through an entire keyspace in minutes to hours.

This is enabled by the original design of the hashing functions, like SHA, DES, and MD5, all commonly used hashing functions. They were all designed to be exceptionally efficient (and therefore quick) to compute.

So password crackers have written GPU-enabled parallel computation of the hashing functions. These run on exceptionally fast GPUs like the AMD Radeon series and the nVidia Tesla series.

To combat these, companies have started sending their passwords through thousands of iterations of the hashing function, which dramatically increases the time required to crack passwords. But really this only means that more computation is required to crack them.

**The Internet**

Many attacks on internet infrastructure and on targeted sites depend upon massively parallel capabilities. In particular, hackers often use Distributed Denial of Service (DDoS) attacks to bring down perceived opponents. Hackers often use an array of thousands of computers, called a

**botnet**, to access a web site simultaneously, overloading the site's capabilities.

Distributed computing is an emerging technology that depends directly on the Internet. Various problems can be split into clean pieces and solved by independent computation. These include peaceful projects such as the spatial analysis of the shape of proteins (folding@home), the search for direct gravitational wave emissions from spinning neutron stars (Einstein@home), the analysis of radio telescope data for extraterrestrial signals (SETI@home), and the search for ever larger Mersenne prime numbers (GIMPS).

But not only have hackers been using distributed computing for attacks, they have also been using the capability for password cracking. Distributed computing is well suited to cryptanalysis also.

**Exascale weapons**

Recently it has been discussed that high-performance computing has become a strategic weapon. This is not surprising at all given how much computing gets devoted to the task of password cracking. Now the speculation is, with China's Tianhe-2 supercomputer, that weaponized computing is poised to move up to the

**exascale**. The Tianhe-2 supercomputer is capable of 33.86 petaflops, less than a factor of 30 from the exascale. Most believe that exascale computing will arrive around 2018.

**High-performance computing**(HPC) has continually been used for weapons research. A high percentage of the most powerful supercomputers over the past decade are to be found at Livermore, Los Alamos, and Oak Ridge.

Whereas HPC has traditionally been aimed at floating-point operations (where real numbers are modeled and used for the bulk of the computation) the focus of password cracking is integer operations. For this reason, GPUs are typically preferred because modern general-purpose GPUs are capable of integer operations and they are massively parallel. The AMD 7990, for instance, has 4096 shaders. A shader is a scalar arithmetic unit that can be programmed to perform a variety of integer or floating-point operations. Because a GPU comes on a single card, this represents an incredibly dense ability to compute. The AMD 7990 achieves 7.78 teraflops but uses 135W of power.

So it's not out of the question to amass a system with thousands of GPUs to achieve exascale computing capability.

I feel it is ironic that China has built their fastest computer using Intel Xeon Phi processors. With 6 cores in each, the Xeon Phi packs about 1.2 teraflops of compute power per chip! And it is a lower power product than other Xeon processors, at about 4.25 gigaflops/watt. The AMD Radeon 7990, on the other hand, has been measured at 20.75 gigaflops/watt. This is because shaders are much scaled down from a full CPU.

**What is the purpose?**

Taking a step back, I think a few questions should be asked about computation in general. What should computation be used for? Why does it exist? Why did we invent it?

If you stand back and think about it, computation has

**only one**purpose. This is to extend human capabilities; it allows us to do things we could not do before. It stands right next to other machines and artifices of mankind. Cars were developed to provide personal transportation, to allow us to go places quicker than we could go using our own two feet. Looms were invented so we could make cloth much faster and more efficiently than using a hand process, like knitting. Telescopes were invented so we could see farther than we could with our own two eyes.

Similarly, computation exists so we can extend the capabilities of our own brains. Working out a problem with pencil and paper can only go so far. When the problems get large, then we need help. We needed help when it came to cracking the Enigma cipher. We needed help when it came to computing the cross-section of Uranium. Computation was instantly weaponized as a product of necessity and the requirements of survival. But defense somehow crossed over into offensive capabilities.

With the Enigma, we were behind and trying to catch up. With the A-bomb, we were trying to get there before they did. Do our motivations always have to be about survival?

**And where is it leading?**

It's good that computation has come out from under the veil of weapons research. But the ramifications for society are huge. Since the mobile revolution, we solve problems that can occur to any of us in real life, and build an app for it. So computation continues to extend our capabilities in a way that fulfills some need. Computation has become commonplace and workaday.

When I see a kid learn to multiply by memorizing a table of products, I begin to wonder whether these capabilities are really needed, given the ubiquity of computation we can hold in our hands. Many things taught in school seem useless, like cursive writing. Why memorize historical dates when we can just look it up in Wikipedia? It's better to learn

**why**something happened then

**when**.

More and more, I feel that we should be teaching kids

**how**to access and understand the knowledge that is always at their fingertips. And when so much of their lives is spent looking at an iPad, I feel that kids should be taught social interaction and be given more time to play, exercising their bodies.

It is because knowledge is so easy to access that teaching priorities must change. There should be more emphasis on the understanding of basic concepts and less emphasis on memorization. In the future, much of our memories and histories are going to be kept in the cloud.

Fundamentally, it becomes increasingly important to teach creativity. Because access to knowledge is not enough. We must also learn what to do with the knowledge and how to make advancements. The best advancements are made by standing on the shoulders of others. But without understanding how things interrelate, without basic reasoning skills, the access to knowledge is pointless.