Bitcoin Forum

I created a new bitcoin address in my bitcoin-qt client (0.8.2), and suddenly there is a transaction of 0.001 BTC to this address, with 88 confirmations already (although I created this address only a few seconds ago!).

This is the transaction number: https://blockchain.info/tx/f6f2e613f6653a3b47f92fd70ff4d1ccc847811294f734a5e9f310c5b9eb063a

WTF just happened??  ???

its got 6+ btc in it now, lucky you!

could this be a bug?

could it be a hard collision?

No it doesn't, he linked you to the transaction, not the coin address.

ahh my mistake, thanks for clarifying.

UPDATE:

The address to which I received 0.001 BTC is https://blockchain.info/address/12k71HDvr3me6ttLr43uMgCCAhgLXNJs8T

It seems to be my "change" address (which was "hidden" inside the client from my view, but used for receiving change before??) because the first transaction to it, is at 2013-05-07 23:54:20, from my other address.

BUT! It DOES NOT explain, why, and from where, there is a 2013-07-11 08:00:19 transaction of 0.001 BTC to it. It was about 12 hours ago, and I have not received of sent any BTC for 10 days.

your randomly created change address seems to be one of the many millions of addresses already in use. you have just won the lottery.

i suggest not using that address as obviously someone else has it too..

i dont think this is the first time a address 'collision' has occured which is why v9 of bitcoin-QT will start using messaged to allow recognition of transactions, to avoid merchants using fresh addresses per transaction. thus reducing the chances of 'collisions' becoming a regular thing.

most people think that there is no chance of a collision unless you create billions of addresses. the actual fact is that you have 1 chance WITHIN those billions of addresses.. so it could be the 10th address you make or the 9,999,999,999th address or so on.

Rescan your wallet, there should be over 8 BTC stored on it.

Did you ever backup your wallet and restore it? Bitcoin QT pregenerates a bunch of addresses that you never see. If you restored your wallet, you may not have scanned the whole block chain. You might have 8 more coins that you don't know about. Start bitcoin qt up with the -rescan flag.

wtf are you talking about? Stop spreading FUD.

There are over 20 BTC in my wallet, and the 8 BTC are counted in (I believe, but will try to rescan just to be sure).

The weird thing is, that I did not send or receive any transactions in 10 days, so how can there be a transaction to my "hidden" address (which I obviously never gave to anyone) dating just 12 hours ago?

You don't own this address do you?

https://blockchain.info/address/1DSu8QqECJFFx9vmTp1MiT3PqHND6LLyTx

The address was already in the block chain. It is known. Someone sent you 0.001 BTC. You didn't get it as change for yourself. The address you posted, has been public since May.

No, I don't own this address.

I agree, that actually it has been public since May (on the blockchain), but I never gave it to anyone as an address to pay to.

So, the most realistic explanation that seems possible to me, is the same as yours - that someone randomly sent me 0.001 BTC.

Then the question is - WHY?

In the same transaction that sent me 0.001, it also sent 0.001 BTC to hundreds of other addresses (and there were a few larger sums too).

I can only see two possible explanations to this:

1) someone is trying to create confusion and scare people, by trying to make them to believe, that an address collision has happened (because in theory this COULD be an explanation, although much less possible).
2) someone is trying to "launder" bitcoins, and even goes to the extreme of sending BTC to random people, to better hide the money trail.

Even with trillions of addresses, there would still be no collision. 2^256 is a very big number, almost as all the atoms in the visible universe.

He probably can't understand how big 256 is let alone 2^256. I didn't even think it was worth arguing it's so stupid and has been discussed endlessly.



I don't have an answer for this. It would be interesting if we could find out who owns it or noticed a pattern with it. Who knows.

I'd still be curious on your rescan though if it turns up an extra 8.

I agree, that collision is (almost) impossible, but this could be used to create panic between those who do not understand bitcoin very well.

I think this could potentially be very serious (a social "attack" to ruin bitcoin's reputation?), and should be looked into further.

There will be (at least) hundreds of bitcoin users, who will think that their "newly created address" already contains BTC (as I thought at first), and if they are not familiar with bitcoin, they may very well decide it must be an address collision (suspicious fact - the first "answers" to my question "what happened?" were exactly that - "collision!"; luckily I myself know about bitcoin too much, to believe that that was the case, but many others could be easily convinced that it was collision).

I said there will be hundreds (of bitcoin users affected), only judging from this one transaction that I know of. In reality, there may have been hundreds of such transactions, ant the number of such users could be tens of thousands.

Rescanned it. As I expected, no "extra" BTC.

Then I'm wondering if your first post isn't quite accurate.

In your transaction list, do you see the 8 btc transaction back in May? Did you create a new address and think it was this one by selecting not the newly created one, but this slightly older one? Also coincidentally, this transaction happened and you didn't notice it until after you made the new address?

I have made an outgoing transaction of 0.16 BTC in 2013-05-07 23:54:20 from 1PFYcabWEwZFm2Ez5LGTx3ftzzmxJvnumK (mine) to another address (not mine).

https://blockchain.info/tx/28151d2b28920bace33463573f25679405cb4658cc0b4fbf73fcd9f04791c28e

0.16 BTC got sent to that address, and 8.12392643 BTC was sent to 12dcw9xbN1sj5FPjTVg5CThXjLbLv5Wu2S as change.

That is all fine, the problem is - who and why sent me 0.001 BTC to this half-hidden address on 2013-07-11 08:00:19

Let's toss a number of stars out there per galaxy. 1 trillion. 10^12  (Galaxies range from 10^7 - 10^14) 1,000,000,000
Let's almost halve the number of galaxies in the observable universe and call it a nice round 100 billion or 10^11 100,000,000

That gives us 10^23 stars in the universe.

2^256 always sounded confusing to me. Let's round it down to a nice even 10^77 power.

If you generated as many bitcoin addresses as all the stars in the universe (so the 1 trillion times 100 billion)
Then Sha hashes / number of stars in the universe equals

Your chances of collision are then 1 in 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

Give or take a few zeroes because I'm not trying too hard here.

So... no, it's not going to happen.

If EVERY single person on this planet (round up to 10 billion just for fun) also generated 10^23 addresses...

The chance of ONE person generating a collision increases all the way to 1 in 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000

Get the point?

Yes, you misread what I wrote.

I KNOW, that collision is impossible.

When I said "there will be hundreds (of bitcoin users affected)" I meant, that there will be hundreds of users who will receive 0.001 BTC randomly, and therefore, there will be hundreds of users who will THINK, that collision happened.

Note that a bitcoin address collision takes place in a 2¹⁶⁰ space, not a 2²⁵⁶, but a 160 bit collision is still unfathomably rare.

Let me to sum up and repeat:
1. I know that collision is impossible.
2. Most people do not know that collision is impossible.
3. In the transaction which sent 0.001 to my address, there were also hundreds of other addresses, to which 0.001 BTC was sent.
4. At least hundreds of people will receive random 0.001 BTC.
5. Since most people believe that collision is possible, then after receiving 0.001 random BTC, they will think, that collision happened (even if it didn't actually happen at all).
6. These hundreds of people will start to PANIC!!!
7. That is why this should be addressed/discussed/explained.

In real life analogy, this would be similar to someone walking around and throwing money at random people. If this actually happened in real life, I believe it would cause a HUGE panic, especially if left unexplained.

Oops. You're right, my bad. Halve the zeros on the chances there, those are your odds, still wildly small.


You misinterpreted my response. It wasn't to convince you, it was for those other people who thunk it. I'm putting it up there for their benefit.

some people have no clue about maths and randomness

the only time to truly say that it would take trillions of attempts to collide is if there was only 1 address in existence that had the hex code of all F's and a brute force machine began at 0's in increments of 1 digit.

the reality is that there are millions of people using bitcoin all with atleast 2 addresses, and some merchants ploughing through hundreds of random addresses per day. making the amount of existing addresses quite high.

and those addresses are not at the end of the hex range. they are randomised throughout it.

so it IS POSSIBLE that out of trillions of addresses

the person can come across a used address on the 10th chance of brute forcing. and then never get a second positive result for the rest of the trillion attempts

the person can come across a used address on the 1 millionth chance of brute forcing. and then never get a second positive result for the rest of the trillion attempts

the person can come across a used address on the 1billionth chance of brute forcing. and then never get a second positive result for the rest of the trillion attempts.

research the word RANDOM..

hmm.. if this cannot be comprehended. lets simply it.

a 4 digit combination lock.

you say it will take 9999 attempts to brute force the lock open.. WRONG.

if i have the combination 0002 and another person had combination 0200 and 8 other people had other random numbers..

will it still take 9999 attempts to hit a used number..

it could take 2 chances or 9999 chances or any number inbetween....

your maths of the 2^160 is the MAXIMUM chances.. not the minimum...

collisions can happen..

sorry to inform you of this.. and now you knwo why gavin and TBF crew are dealing with this with version 9 of bitcoin-QT

Ah, sorry then. My bad :)

I don't think that's the case.





There is a huge difference that I don't think you understand. You might get some math, and randomness. But you can't even grasp the difference between 1 trillion and 2^160.

It will take an average of about 5000 tries.

Generating a collision with a specific 160 bit address requires an average of 2¹⁵⁹ attempts.

Why not? This happened to me, I came here for an answer, and the first answer I got was "collision happened!".

I know that collision did not happen, because I understand bitcoin enough, so I did not believe this.

If there was someone else in my place, he/she may have very well believed that collision happened, after getting such an answer.

so a 4 digit combination lock.. one guy has 0002

i brute for attack starting at 0001 in increments of 1 digit.... found 2nd attempt.

now imagine there are 9 other people with random 4 digit combinations..

it is not 9999 chances just to get a used number.. its a MAXIMUM of 9999 chances. and a minimum of 1.

there are more then 1 bitcoin address in existence so divide the MAXIMUM possibilities, by the addresses in existance. and you will have a more accurate value of chance to collide..

saying this is not to cause panic. and others trying to fluff over the numbers, hiding the truth wont help either as thats concealing the truth from people. atleast the bitcoin foundation is working on a solution for this, as collisions are a thing to be weary of.

EDIT: it would take that high number of chances everyone talks about to find a SPECIFIC address. but to just randomly collide with a used address is much much much lower

Let's be conservative, and assume all human beings on earth would use one billion BTC addresses each. If that's not conservative enough, I don't know what you need!

Then, the probability to generate a collision for a new address is still roughly 2e29. That is a 2 and then 29 zeros behind. That is a hundreds of billions of billions of billions. Forget about this possibility.

For franky1, you keep saying that because they are spread over the interval, a collision gets much more likely, but it does not dramatically reduce the probability as you seem to believe. In your example of 10000 possibilities, if there are 10 addresses in use, there are 1/1000 chance of collision, and on average you need to test 500 to find a collision. I did the same calculation in the large number above.

Additionally, forget about people spending money to "spread fear that a collision can occur". Only very few people would react in the same naive or paranoid way as you do, don't generalize.

My guess is you played satoshidice or something similar. It happens that the payout takes several days.

Unlikely doesn't mean impossible. It can happen, but odds are it won't. It's like flipping a coin and having it rest on it's edge, but even less likely; the odds are so low that you can say it is "impossible" and only the more pedantic will correct you.

I came here, asked what happened, and the first answer was "collision happened".

I did not believe this answer, but is it really so naive or paranoid to believe, that most people would trust the answer, if it was given to them?

Besides, did you even read my post? What satoshidice has to do with anything, if I explained, that this address was never purposefully used? Why would satoshidice send BTC to random addresses? And no, I never played satoshidice or any gambling games, on any of my addresses (but even if I did, your "guess" would still be irrelevant).

_{p.s. offtopic - autocorrect suggestion for "satoshidice" - "dictatorship"  ;D}

It's more like a possibility of flipping a coin, and having it freeze in mid air. Or the possibility of all oxygen molecules around you bouncing away from you at the same time, and you suffocating. It CAN happen, but for any practical purposes it is impossible.

http://en.wikipedia.org/wiki/Birthday_attack#Mathematics (http://en.wikipedia.org/wiki/Birthday_attack#Mathematics)

Regarding panic: the list of people who know what a collision is AND are incredibly bad at math is very small.

Other similarly plausible alternatives include (but are not limited to):

• OP's computer got hacked, and the hacker sent them the coins either accidentally or for the lulz.
• Santa Claus was watching and sent him his present early.
• He is dreaming that he won 8 BTC, and none of us really exist.

I also received 0.001 to one of my addresses from 1DSu8QqECJFFx9vmTp1MiT3PqHND6LLyTx.
I think it is dirty money and sender want to taint coins as much as possible.

Indeed


Enjoy your stupidity franky: https://bitcointalk.org/index.php?topic=246544.msg2614500#msg2614500

Yeah, the first guy was trolling. That's why you got that response.



You keep on talking about a tiny 4 digit number lol.

YOU DON'T HAVE A FUCKING CLUE HOW BIG THESE FUCKING NUMBERS ARE.



... really? Now someone took it from a 4 digit number and reduced it to a low 3 digit number lol.

You guys need to seriously, take a college level math class that talks about exponents and... zeros. lol.



There are so many ways to try and explain this but the people that won't believe it, are probably not mentally capable of figuring out why.

It's a big number but not as big as you said. 2^256 is 0.12% of the atoms in the visible universe:

click (http://www.wolframalpha.com/input/?i=2^256)

Of course a collision is highly unlikely.

It's just as big as I said. I never said it was bigger than every atom in the observable universe. I was saying stars. Which is already a pretty big number, atoms of course is even bigger.

I wasn't replying to you.

 :o

Oops. I'll watch who you're chastising next time. Thought it was me lol :D I even quoted the damned conversation and didn't read it. Sorry :(

It is extremely rare. But still, not impossible. If you think this number is impossible try the probability of intelligent life on a planet; that my fellow bitcoiners is a number near infitesimal.

You, or we, have no idea of the probability of intelligent life appearing on a planet. All we can empirically quickly estimate is... about 1/10, looking at the solar system :P

Oh wow, now to aliens.

Here's the problem with calculating intelligent life probabilities. Sure, we can estimate how many stars there are, already been done in this thread. Life has not been found to exist outside of our solar system, period. So, what numbers are you using for your calculations for green or gray guys with huge heads?

read : http://download.wpsoftware.net/bitcoin-birthday.pdf

 ::)


Going to quote another recent thread. Because this is a stupid argument as well. If you can really generate that many addresses, the collision that you'll find, will be with one of your own addresses (which would be empty) And the reward of finding a block is so much higher than the probability of finding a collision and the difference between the two happening is so small that you guys really don't understand how many zeros are on these numbers and what that means.



and for good measure:

It's pretty easy, you just have to take the data you have. Number of planets/number of planets with the right atmosphere, distance to the sun, water etc.... I think NASA had some calculations to that alone. Then you have to factor in the probability of the right aminoacids mixing together in a friendly environment so that evolution can take it's course and the chances that no catastrophic event wipes out all life on it through a few billion years. Most of those propabilities exist somewhere on the net, I am just too lazy to search them out now :D

You assume that life can only be based on carbon/water/aminoacids. Well, you assume that intelligent life is necessarily something like us, or like what we know, or at the very least like what we can imagine. Same bias also led us to believe in geocentrism and heliocentrism.

my, you assume very much about me. and, I might add, of course I assume that life is based on carbon. on what else? there are only so much elements you can find and until now there are only idle speculations about other forms of life. and what the fuck does that have to do with anything? Even if I would assume there is another form of life, if they find us you have your possibility of finding a fucking double wallet...

I also received 0.001 BTC from this unknown bitcoin address 1DSu8QqECJFFx9vmTp1MiT3PqHND6LLyTx.
What could the sender's purpose be?