same private key?

[mezzaluna]

That would not be possible since every Private key made is unique and having the same private key would be a breach in security. The blocks where they are stored are also different and since there are a lot of wallets being made daily, there have been no issue regarding the same private key. Blockchain Technology boasts its security regarding these kinds of matter and that is why the same private key won't be produced.

[1714126168]

1714126168

[1714126168]

1714126168

[witcher_sense]

That would not be possible since every Private key made is unique and having the same private key would be a breach in security. The blocks where they are stored are also different and since there are a lot of wallets being made daily, there have been no issue regarding the same private key. Blockchain Technology boasts its security regarding these kinds of matter and that is why the same private key won't be produced.

Private key is a random binary number, which is used to spend your bitcoins corresponding to that private key. Imagine your bitcoins stored in safe deposit box and in order to open it you have to use your own key. That key is your private key, binary number. That number is not stored inside blockchain, it is stored inside your encrypted wallet, protected by password. In order to send bitcoins somewhere, you have to sign a transaction with your own key. You literally open your deposit box and hand over coins to another deposit box, which could be owned by you or another person. In order to achieve maximum security and privacy, you never reuse your old deposit box. The technology used to generate your safe deposit box key is so unique that it is nearly impossible to create identical keys, so you can be sure that you are the only one who controls your own deposit box.

[taufik0911]

That would not be possible since every Private key made is unique and having the same private key would be a breach in security. The blocks where they are stored are also different and since there are a lot of wallets being made daily, there have been no issue regarding the same private key. Blockchain Technology boasts its security regarding these kinds of matter and that is why the same private key won't be produced.

Private key is a random binary number, which is used to spend your bitcoins corresponding to that private key. Imagine your bitcoins stored in safe deposit box and in order to open it you have to use your own key. That key is your private key, binary number. That number is not stored inside blockchain, it is stored inside your encrypted wallet, protected by password. In order to send bitcoins somewhere, you have to sign a transaction with your own key. You literally open your deposit box and hand over coins to another deposit box, which could be owned by you or another person. In order to achieve maximum security and privacy, you never reuse your old deposit box. The technology used to generate your safe deposit box key is so unique that it is nearly impossible to create identical keys, so you can be sure that you are the only one who controls your own deposit box.

most likely impossible, as you explain
but it can happen if there are bugs and this possibility is very small
privatekey works like a username where there is very little chance of the same username on a website unless there is a bug

[vapourminer]

privatekey works like a username where there is very little chance of the same username on a website unless there is a bug

no, it doesnt

a forum or website checks a new username against its database to see if its used. if it is, you are promoted to choose a different one. a private key is just a random number. what generates that private key (a program, dice, cards, coin flips, radioactive decay, whatever) doesnt check to see if its used. its just astronomically high that you generate a private key thats "used" already.

[Tipstar]

Sorry for hijacking a bit, I know the Public key is associated with the private key so wherever I use the private key, I get the same public key.
Is there a specific way of defining the Public key from a private key?
As private key are longer (51-52) and public keys shorter, is there any chances that a different set of private key be associated with same public key.
Furthermore, if there's an association between public and private key, would it make easier to guess the private keys from the public key?

[o_e_l_e_o]

Is there a specific way of defining the Public key from a private key?

Absolutely. It's called elliptic curve multiplication. In short, you multiply the private key by the generator point of the secp256k1 curve. The generator point is a fixed value, and is the same for every person and every key, so the same private key multiplied by the generator point will always result in the same public key.

As private key are longer (51-52) and public keys shorter, is there any chances that a different set of private key be associated with same public key.

Private keys are only 51-52 characters when they have been converted to Wallet Import Format (WIF). A raw private key is 64 characters of hexadecimal.

In total there are a little under 2²⁵⁶ possible private keys, a little under 2²⁵⁶ possible public keys, and exactly 2¹⁶⁰ possible addresses. Therefore, no two private keys will lead to the same public key, but multiple public keys (and therefore private keys) can lead to the same address.

Furthermore, if there's an association between public and private key, would it make easier to guess the private keys from the public key?

Guessing the private key from knowledge of only the public key is impossible.

[witcher_sense]

Sorry for hijacking a bit, I know the Public key is associated with the private key so wherever I use the private key, I get the same public key.
Is there a specific way of defining the Public key from a private key?
As private key are longer (51-52) and public keys shorter, is there any chances that a different set of private key be associated with same public key.
Furthermore, if there's an association between public and private key, would it make easier to guess the private keys from the public key?

You normally never see or deal with private keys or public keys while using your HD-wallet. Bitcoin address is not the same thing as public key. In essense, bitcoin address is a result of double hash of your public key. In case an attacker knows your bitcoin address, he first needs to bruteforce your public key and only then he can start bruteforcing your private key. It is kind of double defense system, however it is hard to unhash hashes and infeasible to "calculate" elliptic curve multiplication back.

[Rafiqul]

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, if someone like you gets the same private key then that person will have complete control over your wallet. But in reality it is impossible to generate the same private key and the same bitcoin address. Take care of your personal key and never try to share it with others so that you do not have access to your wallet. Otherwise the fraudster will spend all your funds.

[zasad@]

https://keys.lol/
Try your luck if you don't understand what 2²⁵⁶ means.

Then read this
https://www.reddit.com/r/Bitcoin/comments/1ohwvu/bitcoin_your_money_is_secured_by_the_laws_of_the/ccs5g52/
and this
https://www.reddit.com/r/theydidthemath/comments/1x50xl/time_and_energy_required_to_bruteforce_a_aes256/

I wouldn't worry about someone generating the same key

[ufaiz50]

I don't know and have never experienced that, because in my opinion it is impossible based on this key type the same as the encryption model that the blockchain has with sha256. But based on what some users say "possible", is there any concrete information about the private key model of the wallet? Especially if we see that the combination of numbers, lowercase and uppercase can make more than a million results.

[PIMPdev]

 ?

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 but what for how do you suppose to use it

[o_e_l_e_o]

In essense, bitcoin address is a result of double hash of your public key.

Importantly, an address also includes a checksum.

In case an attacker knows your bitcoin address, he first needs to bruteforce your public key and only then he can start bruteforcing your private key.

Knowing an address provides exactly zero help when it comes to bruteforcing a public key, and knowing a public key provides exactly zero help when it comes to bruteforcing a private key. An attacker would still have to exhaust half the search space, on average.

however it is hard to unhash hashes and infeasible to "calculate" elliptic curve multiplication back.

It is not hard to reverse a hash function - it is impossible.

the same as the encryption model that the blockchain has with sha256.

A hash function is not encryption.

[aryadiningrat123]

Bitcoin private keys cannot be the same from one person to another because Satoshi Nakamotor has designed the best possible private key generation, because the random private key generation for words from 1 to 9 and from a to z cannot be the same, so everyone will have one private key each

[Mr.sprin]

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.

[witcher_sense]

Knowing an address provides exactly zero help when it comes to bruteforcing a public key, and knowing a public key provides exactly zero help when it comes to bruteforcing a private key. An attacker would still have to exhaust half the search space, on average.

Thank you for the corrections, but I personally prefer avoid strong adjectives when it comes to questions about odds, sometimes I fail and use "infeasible" insted of "extremelly unlikely" and "almost impossible". If it can happen, it will happen, this is how I see it. It may be that knowing bitcoin address provides zero help, but at least it gives some information to an attacker: existence of UTXO and amount of bitcoin. Address is now active and therefore more interesting than empty, inactive ones. Still, with the current computation power, it is impossible to crack specific address. But what if an attacker is not interested in specific address, but in all addresses with balance. I have heard of so-called "bitcoin collider" pools where they create a list of known bitcoin addresses with funds and then searching for collisions. What they do is simply a calculating of bitcoin addresses: private key -> public key -> address and comparing them with the list of known addresses. It looks like stupid waste of energy, but sooner or later they may find something.

[casperBGD]

Knowing an address provides exactly zero help when it comes to bruteforcing a public key, and knowing a public key provides exactly zero help when it comes to bruteforcing a private key. An attacker would still have to exhaust half the search space, on average.

Thank you for the corrections, but I personally prefer avoid strong adjectives when it comes to questions about odds, sometimes I fail and use "infeasible" insted of "extremelly unlikely" and "almost impossible". If it can happen, it will happen, this is how I see it. It may be that knowing bitcoin address provides zero help, but at least it gives some information to an attacker: existence of UTXO and amount of bitcoin. Address is now active and therefore more interesting than empty, inactive ones. Still, with the current computation power, it is impossible to crack specific address. But what if an attacker is not interested in specific address, but in all addresses with balance. I have heard of so-called "bitcoin collider" pools where they create a list of known bitcoin addresses with funds and then searching for collisions. What they do is simply a calculating of bitcoin addresses: private key -> public key -> address and comparing them with the list of known addresses. It looks like stupid waste of energy, but sooner or later they may find something.

did not know that this is even possible, but of course is it, and in the end after enough time, one could find some collision, it is not likely event, but i agree, if it is possible, it will eventually happen
just probability that is stuck to zero, it is impossible, when it is not zero, than some number, no matter how small, it leads to something happen after enough time

[o_e_l_e_o]

If it can happen, it will happen, this is how I see it.

Without getting too much off topic here, this logic is incorrect.

Given that entropy is always increasing towards the eventual heat death of the universe, then there is finite amount of time in which things can happen. Therefore, just because something can happen does not guarantee that it will happen. Even if we assume that time is infinite, this also does not guarantee that everything which can happen will happen, as infinite does not necessarily mean everything. There are infinite numbers between 1 and 2, but none of them are 3. The line y = x will continue infinitely, but will only ever visit the value of 1 once.

My point about hashes is quite different though. Reversing a hash is quite literally impossible. Take SHA256 as an example. The input in to SHA256 can be any amount of data up to around 2 exabytes (2 million terabytes), but the output is always a string of 64 hexadecimal characters. Therefore, data from the input is lost during the process which makes it impossible to reverse. Although finding collisions is possible (but difficult), you can't definitely tell me what my input is. Just as if I told you I have two numbers which add up to 1000, you could give me two numbers which fit the criteria but have no way of knowing if they are the same two numbers which I am using.

[witcher_sense]

My point about hashes is quite different though. Reversing a hash is quite literally impossible. Take SHA256 as an example. The input in to SHA256 can be any amount of data up to around 2 exabytes (2 million terabytes), but the output is always a string of 64 hexadecimal characters. Therefore, data from the input is lost during the process which makes it impossible to reverse. Although finding collisions is possible (but difficult), you can't definitely tell me what my input is. Just as if I told you I have two numbers which add up to 1000, you could give me two numbers which fit the criteria but have no way of knowing if they are the same two numbers which I am using.

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.

We don't need to create an algorithm for reversing hash functions, actually. Even if it were possible, it wouldn't give us much information anyway. After all, our goal is to find private key not public key, public key calculation and further hashing into bitcoin address is just for verification (whether or not the private key we found can be used to sign a transaction). What we do is generate a private key, calculate corresponding public key and then applying (RIPEMD160(SHA256(public key))) function and base58 encoding. If our value is matching with sought value, we are fine, if not, we continue until death of universe. Personally, if had a huge amount of proccesing power, I would spend it on mining of new bitcoins, it would be more profitable and more rational than finding the same private keys.

[budi691]

I am of the opinion that if the private key is the same as yours, it could possibly take your coins, it could happen,
but it is very unlikely to happen, in my opinion the private key is made with very good security standards, so getting the same private key is very difficult to happen.

[NeuroticFish]

If it can happen, it will happen, this is how I see it.

~
The input in to SHA256 can be any amount of data up to around 2 exabytes (2 million terabytes)
~

I'll attempt an easier comparison (maybe not as accurate as yours, but still something more real that just numbers).

The chance is about the same as hand-picking the only one correct grain of sand from a beach, 4 times in a row (randomly different grains of sand for each 4 picks)
You can't do it with a machine (the numbers we talk about are so big the machine would not have enough power to only count those), so you'll have to hand pick.

Now think again about the "it will happen" part.


Edit: I improved (corrected) the math based on @o_e_l_e_o's post