DIY Random Number Generator 227
Compu486 writes "The guys over at Inventgeek have come up with a project and how artical on building
a random number
generator that is less than 100.00 utilizing radioactive decay. Using some
Linux based open source apps and with a little ingenuity and some parts you probably
have laying around your house you can build your own."
Not as geek but safer (Score:5, Informative)
Here's the money graph (Score:5, Informative)
One of the applications I have envisioned for this project is a cheap and easy genuine random number generator. True random numbers in computing are nearly impossible, and successful solutions are very expensive systems based on radioactive decay or atmospheric measurements, for example. Using a small / relatively safe radioactive source and a high res CCD or CMOS sensor and assigning a value to each pixel and perhaps mixing in an algorithm or two with an inexpensive practical PCI card that is capable of generating genuine random numbers. Applications that could greatly benefit from this would be encryption, security applications, Computer AI and the Gambling establishment to name a few.
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Actually, no, none of these really benefit from "truly random numbers". The applicability of randomness to AI is... spurious at best? For gambling, you just have to be reasonably sure that someone can't predict in advance what your random sequence is going to be, and the Mersenne Twister plus any unknown piece of data as a seed is good enough at resisting everything our current understanding of mathematics can throw at it. (Yes, thats security through obscurity... in the same way that hiding your server behind locked doors, a firewall, and a secure password is security through obscurity. Its both necessary and sufficient.)
Encryption, similarly, would not benefit from transitioning from an "almost perfect" pseudo-random generator to a "perfect" random generator. For your security to fall based on random numbers, someone needs to be able to not just come up with a theoretical imperfection (ahah, 200 million runs of this random number generator and you'll notice it slightly skews away from these five integers!) but have to crack it wide open. Yay, yawn.
Now, radiation + poorly understood mathematics = geek high, I know. But in terms of practical application this gets a near zero.
Clarification regarding Twister (Score:5, Informative)
Comment removed (Score:4, Informative)
No analysis? (Score:4, Informative)
For example, see
http://en.wikipedia.org/wiki/Pseudorandom_number_
http://www.phy.duke.edu/~rgb/General/rand_rate.ph
http://www.findarticles.com/p/articles/mi_qa3742/
Re:Old-school (Score:5, Informative)
Second, you can measure "how random" something is (for suitable definitions of "random") by measuring its "entropy", which is a measure of how many "random" bits is in a given input. The entropy of English text is 1.1 to 1.6 bits per character [wikipedia.org], which means to safely obtain a 128 bit key from a bit of English text you need almost as many characters as you want bits. "Smashing on the keyboard's" randomness will probably vary even more, from perhaps as low as ~.5 if you smash poorly to 2.5-3 if you smash "randomly", but you also get the entropy from the timing information, which if you use a very-high-resolution clock contributes several bits itself.
So, basically, this "statistical analysis" problem is extremely well known, and very well quantified, down to the fractional number of bits of randomness that you can extract from a bit of text. Since these fractional bits can just be added together (four "English text characters" at 1.5 bits apiece gives you 6 strongly-"random" bits), the solution turns out to be very simple: Smash on the keyboard longer, until you've got at least as much entropy as you have bits. Voila, a strongly-random key suitable for almost all purposes. (It probably is suitable for all purposes, but taking a key from radioactive decay has the advantage of letting you know the key is random, whereas with this technique you can only be "very, very, very sure".)
Handled properly, it's not a problem.
Many, if not most, modern systems will also maintain an "entropy pool" at the OS level, which uses interrupt timings and other such events to feed the pool, which can then be drawn on by programs in lieu of reading the keyboard directly. This works nicely, and among the inputs used is keyboard and mouse events.
The nice thing about the entropy pool is the input can really come from anywhere. It doesn't have to be totally random to contribute, it just can't be totally predictable.
Don't try this at home, folks! (Score:5, Informative)
First, removing the source from a smoke detector is illegal in the US. I'm not aware of anyone being put in jail for doing it, but with the state of affairs currently I would not go posting the fact that you did it all over the internet.
Second, those sources can be very dangerous if mishandled. The source is coated in a THIN layer of gold and/or silver.. only a few atoms thick. If you touch it with anything you will break the seal and contaminate the object. If you then happen to touch it, you have a good chance of ingesting or inhaling it. This is bad. Am-231 is what is called a bone-seeker. It will be used in new bone growth and eventually kill you by causing bone tumors and other cancers.
Now with a little care you can be pretty safe, but the article in question should have been a little more explict about the dangers involved here.
Nitpicking correction (Score:2, Informative)
Am-231 is what is called a bone-seeker
The isotope used in smoke detectors is Am-241, not Am-231. Am-231 is too unstable to be listed in standard isotope tables.
Of course, all isotopes of Americium are bone-seekers, so your point remains valid, though I find it a bit nannying. The quantity of Am-241 in a smoke detector is really minute.
Re:Why not using a live webcam? (Score:5, Informative)
Re:Don't try this at home, folks! (Score:3, Informative)
True random number from random.org (Score:3, Informative)
You did, as well. (Score:4, Informative)
Re:Is radioactive decay really random? (Score:3, Informative)
A chaotic system would be something where the difficulty in predicting it comes from the complexity of the system, and the ability of small changes to significantly influence the outcome. Radioactive decay doesn't work like that. There's simply a particular event that either happens or doesn't.
Re:More difficult Rnd() generator (Score:2, Informative)
Perhaps he's counting in binary on his fingers, in which case he only needs one hand.
Re:Typically silly (Score:2, Informative)
Re:I seem to remember (Score:4, Informative)
Re:Typos (Score:3, Informative)
Re:Don't try this at home, folks! (Score:1, Informative)
Re:Don't try this at home, folks! (Score:3, Informative)
With some attention to geometry, which is suggested by his parcelling of ash, his 232Th had a reasonable probability of capturing slow neutrons from his small emitter, becoming 233Th, which quickly beta decays into 233Pa which in some days beta decays into 233U . His neutron spectrum was sufficiently fast that more 233U fission than actinide production is plausible. Apart from the low neutron flux of his initiating neutron source, nowhere near enough neutrons are produced in this Thorium cycle to maintain a fast neutron chain reaction, so his reactor would have remained subcritical while still breeding 233U.
His apparatus was not particularly conventional, but was clearly a breeder reactor, in the form: Th-232+n -> Th-233 (22 m) -> Pa-233 (27 d) -> U-233 (1.6*10^5 a).
Incidentally, breeding 233U from 232Th is the long term strategy for India, and some small experimental piles there (and in the West in the 50s and 60s) may have looked much like Hahn's description of his own.
What he might have done next is anybody's guess, but he may have made some gains making a powdered mixture of his 9Be with his 241Am or his 226Ra as is done in some conventional neutron generators.
He was clearly pretty bright (no pun intended), and good at learning and improvising as he went along.
Unfortunately for him, Uranium in general is chemically hazardous, and he is also likely to have been accumulating some 232U which has many alpha and gamma emitters in its decay chain. These were obvious and dangerous environmental hazards (not just to him), not least of which is the reactivity surge from 233U production after shutting down and dismantling his reactor, thanks to the relatively long half-life of 233Pa.