Electrical computers: arithmetic processing and calculating – Electrical digital calculating computer – Particular function performed
Reexamination Certificate
2002-04-22
2004-06-01
Ngo, Chuong Dinh (Department: 2124)
Electrical computers: arithmetic processing and calculating
Electrical digital calculating computer
Particular function performed
C708S255000
Reexamination Certificate
active
06745217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of electronic instrumentation in which a random signal is produced or in particular a random number generator. The invention relates to the apparatus and methods for generation of random numbers or random signals.
2. Description of the Prior Art
Long sequences of random numbers are essential in mathematical statistics, data protection, communication security, mathematical simulation of natural phenomena and technological processes, etc. A random number generator (hereinafter, RNG) is at the heart of any information security technology where it is used for encoding key generation. For some applications the “quality of the random numbers” is absolutely crucial. For instance, if the random numbers used in the data protection applications are not “random enough”, it will make the encryption code breakable and may pose serious information security problems, no matter how advanced and sophisticated the encoding procedure is.
Random numbers are produced by random number generators (RNG's), which for the most part are computer programs based on sophisticated mathematical algorithms. Most standard PC software packages include one or several such algorithmic RNG's. It is commonly recognized that any algorithmically generated digital sequence must develop apparent or hidden correlations and, hence, cannot be truly random. There are several standard random distributions, such as, Poisson, Bernoulli, etc., each of which can be converted to another. These standard distributions relate to truly random processes, meaning the absence of a statistical correlation between different events or numbers no matter how close or distant from one other they are. Such distributions correspond to the maximal output entropy. Thus, the quality of a random number generator is defined by the proximity of its output to one of the standard truly random distributions.
As long as the inevitable faultiness of algorithmically generated random sequences is not critical for an application, there is no need to look for something else. But there certainly exist a variety of important applications for which hidden long-range correlation in the RNG output is unacceptable. For instance, if the RNG is anything but perfect, the encryption code can be broken, and it does happen from time to time. In other words, the vulnerability of the encrypted information directly relates to the defectiveness of the RNG used. The only way to ensure the data protection, no matter how resourceful and well equipped the code-breakers are, is to use a perfect RNG for encoding key generation. In the case of RNG applications in mathematical statistics or computer simulation, the presence of a hidden correlation in the RNG output can and sometimes does make the results of statistical calculations unreliable or even worthless.
The only viable alternative to the inherently faulty algorithmic RNG's is a natural, or physical random number generator. A physical RNG is based on naturally occurring random phenomena, such as thermodynamic or quantum fluctuations, radioactive decay, etc.
Most of the existing physical RNG's are based on low energy random phenomena, particularly, thermal fluctuations (Johnson noise), or electronic quantum fluctuations in solids. All such devices have two major problems. Firstly, they inevitably display some autocorrelations and instability due to the physical nature of the underlying physical processes. Secondly, the low energy fluctuation can be affected by ubiquitous external and internal electromagnetic interference, the noise associated with the device electronic circuitry, acoustic noise, etc. These unwanted signals are never truly random and may well contribute to the deviation of the digital output of the physical RNG from the standard random distribution.
A radioactive decay is a natural process ideally suited as a source of randomness. The energy associated with a single event of spontaneous nuclear decay is by 5-7 orders of magnitude higher compared to other physical processes. Therefore, each and every event of a spontaneous radioactive decay does not depend on any external conditions, such as, the quantum state of atomic electrons, presence of other atoms or electromagnetic fields, ambient chemistry, temperature, etc. In this respect, spontaneous radioactive decay is unique. Several physical random number generators based on radioactive decay are known in the art. However, there is room for improvement.
Generally, the existing physical random number generators based on natural radioactive decay are superior compared to those based on low energy random phenomena. Still, there are several problems remaining.
The first one relates to the physical source of randomness itself. The standard Poisson time distribution of the events only applies to those ideal sources which display neither secondary radioactive decay, nor any kind of induced radiation which could be later mistaken for a primary radioactive decay. The induced radiation may include the X-ray quanta, the electrons knocked out of the atoms by the primary radiation, etc. If anything but the prime events is registered by the detector, then the digital output of RNG will inevitably display some autocorrelations. The reason is that different events, such as the primary and the secondary radioactive decays, or the primary events and the induced radiation, are related to one other and, hence, correlated in time. An additional complication may arise from the fact that the total number of unstable nuclei in a radioactive source gradually decreases in time and so does the mean radiation event frequency.
The second problem is associated with the signal registration method. For instance, if the energy of a single radioactive particle is first converted in electric or acoustic noise and only after that is digitized (as is shown in Mike Rosing and Patrick Emin, Ionization from Alpha Decay for Random Bit Generation. University of New Brunswick.), then one will face all the problems associated with physical RNG's based on low energy fluctuations.
One possible way to overcome the above problems is to utilize a directional randomness of a natural radioactive decay, rather than the temporal randomness. See Edelkind, et al., U.S. Pat. No. 5,987,483 (Nov. 16, 1999). The directional randomness implies that the direction of propagation of emitted radiation produced by individual events is a perfectly random characteristic of the process. However, utilization of the directional randomness requires a plurality of independent detectors surrounding a single source of radiation. Every detector should be supplied with independent electric circuitry. The mutual arrangement of the source and the plurality of detectors must exclude the possibility of detecting a single event of radioactive decay by more than one detector.
In present invention we propose the alternative solution that is thought to be less costly and much easier to implement. The proposed device requires a single detector of emitted radiation and utilizes the temporal randomness of spontaneous decay. At the same time the proposed device solves the problem of producing a standard, correlation free random sequence resistant to any kind of internal and external interference (electromagnetic, acoustic, etc.). Finally, consider a comparative analysis of spontaneous alpha decay versus beta and gamma decay. The whole variety of radioactive isotopes differs by the type of emitting particles.
Alpha decay produces helium nuclei. They have the largest mass and electric charge. Therefore, they get absorbed by the matter within a very short range. In the air alpha particles can travel just a few centimeters. Even a thin sheet of paper will totally absorb them. Typical energy of an alpha particle is around 5-6 MeV (compare to less than 1.5 MeV of the beta radiation and 0.5-1.5 MeV of the gamma radiation). The higher the particle energy is, the stronger signal it produces in the detector. More importantly, the energy of emitt
Figotin Aleksandr
Gordon Alexander
Molchanov Stanislav
Popovich Vadim
Quinn Joseph
Dawes Daniel L.
Myers Dawes Andras & Sherman LLP
Ngo Chuong Dinh
The Regents of the University of California
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