why cant people spend other's money

[shorena]

Its impossible.

Not impossible, just highly improbable 
-snip-

Do you worry about the air in your room spontainously moving into a corner leading to your suffocation? Its the same realm of "improbable". Calling it improbable will give people the wrong impression.

I am quite new to bitcoin, still reading the guide, and being puzzled about this. For example, if somebody just create one million private keys and run one million wallet programs at the same time, he would much likely receive some output that paid to one or more private keys (addresses maybe) he generated, and thus steals others' money
Could this be a problem?

A private key is a 256 bit binary number. When written in hexadecimal this comes to a 64-digit hexadecimal number, which in decimal is approximately 1.158 x 10^77. Each private key will produce a unique public key and corresponding bitcoin address. So there are 2^256 possible combinations of private key, public keys and bitcoin addresses.

No, due to the use of RIPEMD160 there are only 2¹⁶⁰ possible bitcoin addresses (of version 1).

To get an idea of the numbers we are dealing with consider the following.

The world's fastest super computer is currently capable of performaing 33.6 quadrillion (33.6 x 10^15) calculations per second. Even if we assume that this makes it possible to check one private key per calculation (the actual number will be less since checking whether a particular private key agrees with a given bitcoin address will need much more than one calcultion), it would need 3.45 x 10^60 seconds or 1.1 x 10^53 years to try all possible private keys. So to try and steal bitcoins that are at a particular address by trying all possible addresses, though theoritically possible is computationally infeasible.

[cyberguy]

A private key is a 256 bit binary number. When written in hexadecimal this comes to a 64-digit hexadecimal number, which in decimal is approximately 1.158 x 10^77. Each private key will produce a unique public key and corresponding bitcoin address. So there are 2^256 possible combinations of private key, public keys and bitcoin addresses.

No, due to the use of RIPEMD160 there are only 2¹⁶⁰ possible bitcoin addresses (of version 1).

true, this is correct as far as the possible addresses are concerned, but someone who is trying to find the correct private key using brute force will have to try all 2²⁵⁶ private keys, since there is no way to determine which of these will not be linked to a valid address.

however i admit that my statement above is not entirely correct

[gentlemand]

Well, I hope someone somewhere's created a bot to monitor something like this. Astronomically improbable things do happens from time to time.

[hv_]

With ETH this will be able to do.     via the DAO

 

[2c0de]

With ETH this will be able to do.     via the DAO

 

[Supercrypt]

I am mildly confused of the relation of the topic title to the content but any way, to answer your question, it has been clarified by posts before me that it is impossible for one key be duped in 1 million keys because there are roughly 2^160 possible unique keys that can be created. That's just huge of a number, trust me.

[BitsandBites]

Because it does not make sense to let someone else spend your money. That is the only reason why people cannot spend someone else his or hers money.

[Oscoda]

Because it does not make sense to let someone else spend your money. That is the only reason why people cannot spend someone else his or hers money.

Yeah it is obvious that you cannot spend other peoples money. Why would you let someone random make use of your money that is the dumbest think that you can do in this world.

[quintiilieo]

What the hell are you thinking about. Spend others money? are you crazy they make hard effort to gain profit and now you want to spent others money while you are just sitting around and do nothing eating junk foods watching tv? is so unfair if you think that will work it is nonsense question i dont know how old you are even a kid dont ask questions like that.

[~Bitcoin~]

Because it does not make sense to let someone else spend your money. That is the only reason why people cannot spend someone else his or hers money.

Not only sense but this is due to cryptographic security as well as due to this billions of bitcoin address can be generated so there is no any chance of getting same private key for two addresses.

[vlad12]

I am quite new to bitcoin, still reading the guide, and being puzzled about this. For example, if somebody just create one million private keys and run one million wallet programs at the same time, he would much likely receive some output that paid to one or more private keys (addresses maybe) he generated, and thus steals others' money
Could this be a problem?

Why run a million wallets when all the possible private keys to all the possible bitcoin addresses are "stored" here:
    http://www.directory.io/?

Go ahead, flip through it, if you find my address you can have all my coins .

[nanonymousx]

With current computer architecture, it will take about 1 million year to calculate another person's private key from public key.
But, quantum computer, or some future completely different computer maybe can do that in a few days, then that will be the end of Bitcoin.

[bladeandsoulguide]

people spend other people's money

that calles hacker

[Betwrong]

Well, I hope someone somewhere's created a bot to monitor something like this. Astronomically improbable things do happens from time to time.

haha, yeah. But generally we don't think about what will happen if something which can happen once in a billion years happens. If the chances of an event are very small we consider it impossible.

[StoreBit]

because its belong to them. if i ask you that why people cannot think from other;s mind. why peoplenot see with other.s eyes. similary the money belong to them then how can other people will use it with out permission.