Quote from: RealBitcoin on July 10, 2015, 12:23:22 PM

What about this guys:

http://www.dailymail.co.uk/news/article-2711202/It-cooks-inside-like-microwave-Man-61-survives-struck-lightning-10-TIMES.html

So we know that being hit by lightning 10 times is possible , thus:

A 0.000000000000000000000000000152% chance has already happened, and probably even more times around the world, so i`d say

Anything between 1e-28 and 1e-40 chance is probable to happen in our lifetime.

Now you guys say that (on another thread i saw this):

Quote from: enmaku on August 29, 2012, 05:26:37 PM

Given your example of 1 billion users at 10 addresses each:

There are 2^160 or about 1,460,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 possible addresses
In your scenario, 1,000,000,000 people are using 10 addresses each for a total of 10,000,000,000 possible addresses
10,000,000,000 / 2^160 should yield the probability of a collision occurring
10,000,000,000 / 2^160 = 0.00000000000000000000000000000000000000684

So the chances of a collision occurring in your scenario are approximately 0.000000000000000000000000000000000000684%

See why we don't consider collisions an issue?

Thus that is a 1.5e-28 probability that if 1 billion people create addresses, then 1 address can easily be REVEALED!

So consider this, a person can easily create more then 1 addresses, i think the average per person is around 5-6.
(Excluding the fact that there can be malicious guys that create billions of addresses /day, searching for filled balances)

But even if we go with 5-6/life, and looking for 1 billion people (conservative future users of bitcoin).

That is 5,500,000,000 /2^160 = 3.7632527118098114697658753457492e-39

So that is 3.76e-39, and we know around 1e-40 is probable, thus at least 1 unlucky fellow from that 1 billion users will get its account hacked.
And this is only conservatively speaking in a passive situation, involuntary collision (if hackers start to actively search for bitcoin addresses with the purpose of finding them, then we are even more in trouble)

I think the probability should be at most 1e-100, but preferably even lower a 1e-200 to be safe, we need new format of the private key, 2^160 is too little, not to mention, the guy above me said that its only 2^80 which is very unsafe

You have to "cook the books" for something like that to happen. The person described above had to put himself in positions where conditions where lightning would strike. I'm not saying he did it on purpose, but maybe next time he sees a storm cloud over head and begins to smell ozone he should head inside. You could do the same with bitcoin and use poor RNG to generate addresses and you then put yourself in a position where a collision is more likely. For instance using the brainwallet "cat" or "satoshi nakamoto" those are technically collisions but they are due to poor RNG not a fault in the bitcoin protocol.