Sources Of Random Numbers

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Sources Of Random Numbers
Topic Started: Oct 11 2006, 02:23 AM (306 Views)
loki	Oct 11 2006, 02:23 AM Post #1
Advanced Member Posts: 87 Group: Members Member #48 Joined: April 28, 2006	While during a pursuit of researching prng's, a few things occured to me. Most will agree that best source of randomness comes from radioactive decay. Needless to say, that reminds me to buy a new bar of Uranium. Yah right. Nor do I (as most of us) have the resources needed for such a thing. So it occured to me, what could be a cost effective source of randomness for the average joe? then it hit me, traffic camara's; there are live feeds of traffic camara's all across North America, I can only presume about Europe? none the less, a hash of two or more snapshots of such camaras at different locations should be a preety good source of randomness. I should really like for someone to try and explain how this would not be random or even predicable for that matter. Any Input on this?
	c(x) = 3x3 + x2 + x + 2; Find the inverse


insecure	Oct 11 2006, 07:25 AM Post #2
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	No, radioactive decay makes a lousy source of randomness - not because it isn't random (which it is), but because it's radioactive! :-) Your idea is not a new one. Point a webcam out your window at some field of view that will change frequently and arbitrarily - traffic is good, and so is the garden (wind in the trees, birds, all that). Traffic is actually better, if you live in a busy part of town. But don't just use the bits "raw". That lamp-post over there never moves, and often it will be unobscured by pedestrians, so make sure you stir its bits up with lots of other bits. In fact, it's worth using some of the entropy from the image to stir up the other bits somewhat. Lava lamps are a possible. A TV is a bad idea, because the image can be regenerated too easily.



oblivion	Oct 11 2006, 10:00 AM Post #3
Oblivious Posts: 43 Group: Members Member #55 Joined: June 21, 2006	insecure Oct 11 2006, 07:25 AM No, radioactive decay makes a lousy source of randomness - not because it isn't random (which it is), but because it's radioactive! :-) Your idea is not a new one. Point a webcam out your window at some field of view that will change frequently and arbitrarily - traffic is good, and so is the garden (wind in the trees, birds, all that). Traffic is actually better, if you live in a busy part of town. But don't just use the bits "raw". That lamp-post over there never moves, and often it will be unobscured by pedestrians, so make sure you stir its bits up with lots of other bits. In fact, it's worth using some of the entropy from the image to stir up the other bits somewhat. Lava lamps are a possible. A TV is a bad idea, because the image can be regenerated too easily. I think it sounds like a good idea. If Alice use a webcam pointed at the TV to generate a random number, Eve must know both what TV-channel is on AND the exact angle from which the cam is recording. Also she must have the same type of webcam and the EXACT same positioning of any light sources, even the same colours on the walls. Even if Eve accomplish all these things, much will differ between Alice's and Eve's numbers. For example Eve must know the exact time when the number was generated to calculate where the sun was positioned, or even if the sun was out. All these things forces the webcam to behave differently, especially if you use an older webcam. The FPS must also be known to Eve.
	The following statement is true. The previous statment is false.


PulsarSL	Oct 11 2006, 07:04 PM Post #4
Super member Posts: 157 Group: Members Member #7 Joined: September 1, 2005	oblivion Oct 11 2006, 10:00 AM insecure Oct 11 2006, 07:25 AM No, radioactive decay makes a lousy source of randomness - not because it isn't random (which it is), but because it's radioactive! :-) Your idea is not a new one. Point a webcam out your window at some field of view that will change frequently and arbitrarily - traffic is good, and so is the garden (wind in the trees, birds, all that). Traffic is actually better, if you live in a busy part of town. But don't just use the bits "raw". That lamp-post over there never moves, and often it will be unobscured by pedestrians, so make sure you stir its bits up with lots of other bits. In fact, it's worth using some of the entropy from the image to stir up the other bits somewhat. Lava lamps are a possible. A TV is a bad idea, because the image can be regenerated too easily. I think it sounds like a good idea. If Alice use a webcam pointed at the TV to generate a random number, Eve must know both what TV-channel is on AND the exact angle from which the cam is recording. Also she must have the same type of webcam and the EXACT same positioning of any light sources, even the same colours on the walls. Even if Eve accomplish all these things, much will differ between Alice's and Eve's numbers. For example Eve must know the exact time when the number was generated to calculate where the sun was positioned, or even if the sun was out. All these things forces the webcam to behave differently, especially if you use an older webcam. The FPS must also be known to Eve. As well as any "hot pixels" that are specific to that webcam.



oblivion	Oct 11 2006, 09:09 PM Post #5
Oblivious Posts: 43 Group: Members Member #55 Joined: June 21, 2006	And also, Alice could change channels "randomly" while generating the number. And maybe play a couple of home made videos from time to time.
	The following statement is true. The previous statment is false.


insecure	Oct 11 2006, 09:36 PM Post #6
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	Home made videos are a better idea. The problem with TV is not so much that the key is weak as such. Various "this makes it harder" aspects have already been pointed out. It's just that it's weaker - the cryppie does at least have a base to work from. "Joe, this cipher uses a key based on such-and-such a TV program, albeit with various fudge factors to do with angle, contrast, hot spots, etc. We really need to know this. Your budget is twelve million pounds. Here's the tape. Get hill-climbing." But a video of the kids playing football in the local park is unlikely to be duplicated anywhere in GCHQ's database of might-be-useful-one-day archive footage! So it's more secure. But I still think pointing the thing out the window is going to be a better bet. Possibly pointing at the sky (all those lovely moving clouds, and with the infinite variety of sky shades), ideally through some tree branches waving in the wind.



oblivion	Oct 11 2006, 11:32 PM Post #7
Oblivious Posts: 43 Group: Members Member #55 Joined: June 21, 2006	I agree, nature seems to be truly random.
	The following statement is true. The previous statment is false.


Revelation	Oct 12 2006, 08:03 AM Post #8
Administrator Posts: 386 Group: Admin Member #1 Joined: August 23, 2005	Ofcourse it is not random, but we don't have the power to calculate the motion of clouds yet. So that is a great way of getting random numbers. Music may also be a good source for random numbers.
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oblivion	Oct 12 2006, 10:23 AM Post #9
Oblivious Posts: 43 Group: Members Member #55 Joined: June 21, 2006	Yes, music or maybe sound in general. Instead of the webcam you put a microphone outside the window and use the data to generate random numbers. Combine this with the webcam you have a high value of randomness. That is until humans can calculate what other people will be doing every day including how they hold their cigarette when they smoke and how they blow out the smoke.
	The following statement is true. The previous statment is false.


loki	Oct 18 2006, 11:44 PM Post #10
Advanced Member Posts: 87 Group: Members Member #48 Joined: April 28, 2006	I wonder about whitenoise from several sources, or the feedback when to handheld radio's are side by side and one is transmitting, you know the high pitched wail! Or even this would be cool, take a digital radio, Digital radio and calculate the whitenoise from a transmission using 128 hops per second with every 16th or so frequency offset my 0.25mhz. I do this for a living and if you havnt heard it before it kinda sounds like a the effect of talking into a fan. Its really neat.
	c(x) = 3x3 + x2 + x + 2; Find the inverse


fermineutron	Oct 29 2006, 02:12 AM Post #11
Just registered Posts: 2 Group: New Members Member #99 Joined: October 29, 2006	Randomness and speudo-randomness are fun. I think tht it is important to note that true random events are not necessary the best choice for cryptography. Things like nature, traffic cameras etc. have unpredicted bias, while Pseudo Random Number Generator (PRNG hence forth) can be designed with minimal and what more important predictable bias. The downfall of PRNGs is predictability, for example a Liniar Congruental (probably miss-spelled it) Number generators are not cryptografically safe because state N+1 can be easily predicted from state N. Combining a cryptographycaly insecure PRNG with a hash box can sometimes create a cryptographycally secure PRNG but it will probably result is longer generation time than that of a specifically designed cryptographically secure PRNG. For cryptography it is also important to increase the entropy of output stream, hence PRNGs used in cryptography should be unbiased. The cycle length of PRNG is also important for a good crypto system. Natural events which seem random are likely to fall short of PRNGs for crypto purposes either because of a biar or, more likely because of short cycle length. For example if you are using a trafic camera for your random number generator and you are reading 1 pixel off the image, your maximum number of possible values will be rather small, which is adversly effect your implementation. Concept of cycle length is not applicable to this type of PRNG. Generally you want to increase the parameter called Shannons entropy, which is directly proportional to the number of possible alues that can occur in your stream, and for any given set of such numbers shennons entropy will be maximum when all values are equally likely to occur.



insecure	Oct 30 2006, 07:29 AM Post #12
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	fermineutron Oct 29 2006, 02:12 AM Randomness and speudo-randomness are fun. I think tht it is important to note that true random events are not necessary the best choice for cryptography. If you want an uncrackable OTP, they're your only option. Pseudo-randomness is insufficient for OTP security.



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