Increasing Entropy with Crypto4A


Have you ever thought about the increasing disorder in your life? Sure, it may seem like things are constantly getting crazier every time you turn around, but did you know that entropy is always increasing in the universe? It’s a Law of Thermodynamics!

The idea that organized systems want to fall into disorder isn’t too strange when you think about it. Maintaining order takes a lot of effort and disorder is pretty easy to accomplish by just giving up. Anyone with a teenager knows that the amount of disorder that can be accomplished in a bedroom is pretty impressive.

One place where we don’t actually see a lot of disorder is in the computing realm. Computers are based on the idea that there is order and rationality in everything that we do. This is so prevalent that finding a way to be random is actually pretty hard. Computer programmers have tried a number of ways to come up with random number generators that take a variety of inputs into the formula and come up with something that looks sufficiently random. For most people just wanting the system to guess a number between 1 and 100 it’s not too bad. But when it comes to really, really large numbers like the ones used in cryptography, those pseudorandom numbers aren’t good enough.

This All Looks So Familiar…

One of the reasons for this comes down to good old fashioned efficiency. In the old days computers programmers could rely on people to generate pseudorandom input. By sampling mouse clicks or delay between computer keyboard keystrokes you could easily come up with a number that looks nice and random. However, we’ve taken people out of the loop now. Thanks to the cloud and automation and any one of a number of new ways to reduce human input we’ve managed to remove mouse clicks and keystrokes.

That’s fine for running scripts and programs. It’s even good for building things at a huge scale. But it’s really bad when you need something that looks relatively random. And it’s really, really bad when your program relies on that randomness to keep you secure. Kind of like key generation in Public Key Cryptography (PKI).

A group of security researchers working for the National Institute of Standards and Technology (NIST) found out a few years ago that public keys were starting to collide at greater rates than random chance. The study, conducted in 2012, found that 5% of HTTPS and 10% of SSH public keys were duplicates. A collision in a hashing algorithm is when two inputs produce the same output, which renders that hashing function broken. In PKI, having a two different inputs output the same public key is really bad, because it could lead to key collisions that impact a variety of service.

What caused it? As it turns out, lack of orderly disorder. Because automation and non-human interaction have led to other pseudorandom inputs being used in key generation it appeared to the researchers that the same inputs were being used all over the place. That meant that a lot of the public keys that were being generated were being done in such as way as to make collisions more likely. When you look at how many things are relying on automated sources to generate keys it can be quite scary. Think about a smart lightbulb or other IoT device that’s trying to generate pseudorandom input from a CPU that’s just big enough to turn things on. Now imagine that CPU multiplied by the number of smart lightbulbs out there. Not a pleasant thought, is it?

Disorder In The Court

This fascinating discussion came from an interview I had with Bruno Couillard, the President and CTO of Crypto4A. Crypto4A is a company that provides Entropy-as-a-Service. What exactly does that mean?

Crypto4A has an appliance they call QAOS. QAOS is designed to give you the best possible disorder that you can get. It does this the old fashioned way. Instead of trying to use software as a Random Number Generator (RNG) QAOS instead uses hardware sources to generate entropy for their RNG. This includes a quantum RNG, which produces high quality disorder that’s difficult to fake any other way.

QAOS is designed to feed software with entropy to generate randomness sufficient to prevent PKI public key collisions. The software developers can follow the NIST guidelines on EaaS to have the program call an entropy source. QAOS, acting as that entropy source, will seed the RNG on the target system with good randomness and allow it to generate good keys. This could also be configured in the kernel of the OS to call a system like QAOS on boot and start the seed value with a good amount of random entropy in the case of old programs that can’t be modified to call anything other than a system-based RNG source like /dev/random/.


Tom’s Take

The NIST guidelines around EaaS are constantly evolving, but the idea that companies are already racing to fill the void that has been created by insufficient randomness in cryptography is telling. When you think about nth the number of devices that are going to be using PKI for secure communications, the need for something like Crypto4A QAOS is pretty clear. If we are going to rely on automated systems to run our daily lives, we need to have the resources in place to ensure they have a solid foundation of randomness to build on.

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