same private key?

[lepbagong]

the possibility of using the same private key can happen but whether it can be used maybe this needs to be questioned again. if it can't be used, then finally the problem has been resolved besides it can indeed be used.

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[pooya87]

The amount of data, size, structure are known in this case. For a compressed public key, it is 33 bytes hex-number as input for sha-256, and standart SHA-256 hash as input in RIPEMD160 function. Does it make things easier to crack? I guess not, but at least we have something to consider.

ireversibility of the hashes is not about the data size but about the algorithm that they use. to put it simply we can use a simple mathematical formula like x+y. if we know the result of this formula to be something like 12 you have no way of reversing it back to x and y. that is why it is impossible to reverse a hash function.

that formula above is not far from reality either. your RIPEMD160 result is literary the addition of 2 32-bit numbers for each of its hash state items. hash_state[1] = hash_state[2] + d + e where d and e,etc. are computed by bit rotations.

[o_e_l_e_o]

We don't need to create an algorithm for reversing hash functions, actually.

That's true, until we start talking about quantum computers, which is the most likely way that bitcoin will be "broken" in the near future. A quantum computer in a few decades could potentially use Shor's algorithm to reverse elliptic curve multiplication and calculate a private key from a public key. It could not, however, reverse a hash. Since the public key is only revealed when a transaction is made, as long as you do not reuse addresses, then your coins remain safe.

The chance is about the same as hand-picking the only one correct grain of sand from a beach.

An internet search puts the number of grains of sand in the world at around 10²⁰, give or take a few orders of magnitude. 2²⁵⁶ is equivalent to ~10⁷⁷. So the chance is similar to hand picking the only correct grain of sand in the entire world chosen at random, four times consecutively.

[rajakulam]

For bitcoin private keys it is clearly impossible to be the same, because the private key consists of a unique combination of numbers and letters, try to imagine for yourself if an investor who has a lot of bitcoin assets will definitely feel annoyed if he finds out that his private key is the same as someone else's.

[NeuroticFish]

The chance is about the same as hand-picking the only one correct grain of sand from a beach.

An internet search puts the number of grains of sand in the world at around 10²⁰, give or take a few orders of magnitude. 2²⁵⁶ is equivalent to ~10⁷⁷. So the chance is similar to hand picking the only correct grain of sand in the entire world chosen at random, four times consecutively.

You are most probably correct.
I was expecting I may miss some "orders of magnitude", but I thought that should be not a big problem since the goal was easier understanding, not being 100% correct.
However, the idea of adding the "four times consecutively" is very good and although I don't expect too many who didn't understand the initial explanation gasp the difference, I'll add that. Thank you.

[TedMosby]

I thought this is a simple question until I found this is interesting after reading the comments.
so, a private key / wallet address is not purely generated uniquely.

it just close to unique because of the chance to have the same private key / wallet address close to impossible, because the amount of different keypairs that can be generated is huge.
CMIIW.

I like the coin flipping analogy BlackHatCoiner though.

[0t3p0t]

hey,
I wonder, even if the probability so small is, if someone else get the same private key as me could he/she spend my Bitcoins and viceversa? would we have the same Bitcoin Adress?

Yes of course. Though just like what you said the probability is so small like grains of sand. It is all the matter of luck because ever since the creation of crypto I have never been heard of something like the topic had happened. I do hope I am the lucky one who can guess the same private key with those "lost forever" Bitcoins out there.

[Smartvirus]

In imagining OP's question, I imagined something else and that is, no two persons has the same microchip number with regards to phone numbers although, country codes plays a part in this. The least I've heard of is some dormant numbers been recycled can't say if it's really true about that. But then, the point I'm driving at is, the microchip numbers is just a combination that ranges within 100000000000 or less and majority of the world have phones now and still not a single person has the same microchip number. Cases of redirect calls seems to be the only explanation for receiving calls for which it wasn't meant for You.

With that being that, how then would two persons have the same private key?! Especially with the fact that, not so many has the idea of private keys or seed phrase, not so many are into or enthusiastic of bitcoin and the private key or seed phrase are combined in a way that, you really can't make out anything if it,it's just words or alphanumeric combinations that follows no definite other and as such, it's limitless as to how many combinations it can generate. So, having the same private key or seed phrase as someone else is close to impossible and it would be a disaster should this ever happen.

[Traderbtcc]

The chance of this happening is really slim or should I say nearly impossible, since I came to the crypto space have never heard of two people owning the same private key , if that was possible it would have happened a long time ago cause every day Moore people keep creating new wallets, so if it was possible one of them would have had the private keys to other persons wallet, but its not possible because private keys are combination of letters and numbers so there's absolutely no way two people can own the same combination something must be different between them.

[Fatunad]

When you do talk about private key collision then thinking off on what would be the odds is.. It would be good on reading up this thread.

https://www.reddit.com/r/crypto/comments/drxyjq/chance_of_private_key_collision_for_256bit_ecc/
https://www.reddit.com/r/Bitcoin/comments/1ylis1/collision_probability_for_bitcoin_private_keys/

So i wont really be bothering myself on finding some private key with having some balance.

[yohananaomi]

It is true that the private key cannot be the same, the creators of bitcoin do not play in maintaining security, of course with the expensive price of bitcoin the security key is tightly secured, randomized from the numbers 1 to 9 and from the letters A to Z there is definitely nothing the same.

I really agree with you that everyone will make a key with the best possible security and security that can be guaranteed because it uses a very difficult combination and its security will definitely be tested. Obviously, it becomes a priority that is impossible until it is not well controlled. so it will not be possible to have the same private key occur, other than what we really suspect is that private key was taken because did not maintain it properly.
Therefore, if someone says that there are similarities, it is very difficult to prove that with very good security, it can be the same, unless we are indeed hacked by irresponsible people.

[Travel Standard]

This is very difficult or we can say it impossible. Wallet created in such a way that i cannot be duplicate. We especially me sis not hear from anyone that his private key is match to another account.
If we suppose that its happen than answer is ""Yes""

[elisabetheva]

This is very difficult or we can say it impossible. Wallet created in such a way that i cannot be duplicate. We especially me sis not hear from anyone that his private key is match to another account.
If we suppose that its happen than answer is ""Yes""

yes true, theoretically it would not be possible to say that there would be a double private key, because the simulation made was so complicated and for a system error to give an existing private key to the other, it is certain that it will not happen.
the most likely one is the duplication of the private key due to a private error that is not stored properly and is taken by fraudsters in many ways that can be done.

the most frequent one is via email that gives a link where the contents of the scam are, now starting to use telegram which is booming through airdrops which are indeed very easy to manipulate so that we can have a computer entered by the fraudster.
So many ways now live we must look after ourselves properly.

[Innerpumper]

hey,
I wonder, even if the probability so small is, if someone else get the same private key as me could he/she spend my Bitcoins and viceversa? would we have the same Bitcoin Adress?

of course, this is the importance for us to keep private keys from people who can not be trusted because it leaks once our assets can be directly spent or transferred to their personal wallets and none of them can help because of the decentralized nature of bitcoin.

[In the silence]

Learned a lot here.
Thanks to those who answered the question from the OP.

This helps a lot honestly since we should be more aware of a situation like this, though I never heard this kind of problem so maybe this wont exist at all. The developer creates a huge number of combination words to ensure its uniqueness but of course if the wallet comes from suspicious site, then this kind of problem might exist so they can scam the users, its hard to say it.

There are lots of situations where you can gain an experience and knowledge through them. As we can see on his issue, wallet address and private keys or even pnemonic/seed phrase are auto generated and cannot be restored on the database of website wallet address generator unless it the website is used for scamming people.