What is it?

Z1FFER is a true random number generator (TRNG) shield for Arduino. It uses a thermal noise technique known as Modular Entropy Multiplication to generate random numbers.

Why did you make it?

Cryptography depends on high-quality random numbers that originate from a truly random source. When you go to your bank's website, for example, your computer must automatically generate a random "password" (known as a key) to create an encrypted connection with the bank. Your computer could generate this key using an algorithm alone, but the problem with this approach is that if someone knows the algorithm, they can theoretically predict the key and crack the encryption between you and your bank. Therefore many computers have a hardware random number generator that uses a natural source of entropy to generate irreproducible randomness.

However, the Snowden documents revealed that the NSA actively works to insert vulnerabilities into commercial encryption systems, and one way of undermining these systems is to tamper with their random number generation. In 2005 the NSA published a random number generating algorithm with the recommendation that people use it in their systems. Later, security researchers revealed that the NSA method allowed for the existence of a secret key, which, if known, would allow them to predict the output of the algorithm, which would in turn allow the NSA to break any encryption that used their recommended algorithm.

What makes it special?

This generator uses thermal noise – an unpredictable entropic physical force – to create a random bitstream. It is also completely open source, based on a design by Bill Cox and a technique invented by Peter Allen. Since it is open, there are no secrets about how it works and its designs are free to be scrutinized by the public. You are also free to use the technology however you wish.

How do I use it?

The Z1FFER shield is for Arduino. Some familiarity with Arduino programming would help. There are instructions on www.openrandom.org/gettingstarted, as well as some scripts that will let you access the random bitstream. Additional information is available at www.openrandom.org/resources.