Hardware random number generator base on monostable multivibrators dedicated for distributed measurement and control systems

The term distributed, wireless measurement and control systems with asymmetric resources refers to networks created on an ad hoc basis by small autonomous devices, which perform communication and measurement functions, signal processing, also often executive functionality. These systems are severely resource constrained; usually we have to deal with tiny autonomous nodes with very limited computational resources and very limited energy source. Limitations of the nodes are the consequence of the requirements for their size, production costs, location, and that they should be constitute autonomous terminals. Integration into existing infrastructure (i.e. the Internet) and usage of unsecure transmission channels (wireless) make information security of the system a crucial problem. Cryptography provides tools for solving this problem, however, resource constraints influence methods of securing such systems (algorithms, protocols, circuits).
Security of cryptographic systems is strongly connected with generation of some unpredictable, random values. The problem is important and is drawing increasing attention. Establishing pairwise keys in secure communication or generating one-time pad key sequence can serve as examples of the latter. Random numbers are also used in zero-knowledge proof entity authentication algorithms, digital signatures and randomized algorithms for finding large primes. Unfortunately most of the Random Number Generators (RNG) implementations seems to have large hardware requirements. Moreover not all of them are cryptographically secure. It is therefore very important to study how RNG can be built within the constraints of low-power applications.
Generators used in cryptography have to provide output sequences which are, apart from being statistically valuable, unpredictable and secured against attacks. The latter means that one should not be able to predict future bits from generated sequence, even obtaining previously generated bits. This property is called the cryptographic security of the generator.
In this paper, the hardware random number generator based on the 74121 monostable multivibrators
for applications in cryptographically secure distributed measurement and control systems with asymmetric resources is presented. This device was implemented on the basis of the physical electronic vibration generator in which the resonant circuit is composed of two capacitors, two “loop” 74121 monostable multivibrators, D Flip-flop and external clock signal source. The clock signal, witch control D is generated by a computer on one of the parallel port pins. The system of two “loop” 74121 monostable multivibrators, there is a square wave generator with low quality generation. By properly adjusting the frequency of the square wave generation and frequency of the external clock (trigger flip-D), so that their relationship was irrational number, the hardware random number generator is obtained.
For the research of the hardware random number generator is designed lab system consisting of this device and the PC. There is presented programmed the author's acquisition process of random data from the measuring system to a computer. Software of the acquisition process was implemented in C language on the computer, running under the Linux operating system. The service of the parallel port in independent mode of the digital interface input/output was implemented on the basis of C library called "parapin" (a Parallel Port Pin Programming
Library for Linux ).
The presented system was designed, builded and thoroughly tested in the term of cryptographic security in our laboratory, what there is the most important part of this publication. Real cryptographic security was tested based on the author's software and the software environment called RDieHarder. The obtained results will be here presented and analyzed in detail with particular reference to the specificity of distributed measurement and control systems with asymmetric resources.