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Topic: what if two people generate the same private key ? Is that possible (Read 178 times)

mu_enrico
copper member
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what if two people generate the same private key ? Is that possible
June 06, 2018, 11:16:32 PM
#12
Quote from: walkerbitco on June 04, 2018, 10:21:29 PM
what if two people generate the same private key ? Is that possible

Since private key is 256-bit random number, there's no way, in reality, two people generate the same private key.
It's like two people flipping a coin 256 times and expect the exact same result.

PS: If these two people flipping a coin 50 times and have the exact same result. I'd call that a miracle.
DrMill
jr. member
Activity: 104
Merit: 1
Re: what if two people generate the same private key ? Is that possible
June 06, 2018, 11:08:41 PM
#11
I think it's possible, theoretically. But, due to so so low probability, we just don't need to worry about the risk, at least for several years to come.

It's similar to the situation that there's a person who looks exactly like you on this planet. If it ever happens, you hardly know about the existence of the other, therefore do not have to worry about what if your spouse make mistake: going with your identical person, instead of you.  Cheesy. Just kidding!
chiller
full member
Activity: 129
Merit: 101
Re: what if two people generate the same private key ? Is that possible
June 06, 2018, 05:46:30 PM
#10
Yes it is possible and it is proven by project called "Large Bitcoin Collider" https://lbc.cryptoguru.org/about. You can read more there. 
What happens then?
Well that part also is covered in the LBC.
In a nutshell
  • Spend it
  • Do nothing
LTU_btc
legendary
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Slava Ukraini!
Re: what if two people generate the same private key ? Is that possible
June 06, 2018, 05:24:36 PM
#9
Everything is possible in this world Cheesy. But it's almost impossible to generate same Bitcoin address for two people - chances are close to zero. To generate same private keys chances are many times smaller than to generate same Bitcoin address.
HCP above posted link to exact calculations made by one smart guy.
HCP
legendary
Activity: 2086
Merit: 4361
Re: what if two people generate the same private key ? Is that possible
June 05, 2018, 09:17:00 PM
#8
What if two people generate the same private key? The simple answer is that they  will both have the ability to spend any UTXOs that are assigned to that private key. (First to spend wins!)

Is it possible? Yes

Is it likely? No. I forget the exact maths or whom it was that calculated it, but I think the odds of that happening were the same as being struck by lightning while taking a crap seventeen years in a row Tongue

Edit: found it! https://bitcointalksearch.org/topic/m.1315279
bob123
legendary
Activity: 1624
Merit: 2481
Re: what if two people generate the same private key ? Is that possible
June 05, 2018, 02:52:48 AM
#7
Quote from: Cryptocoinbob on June 04, 2018, 10:29:30 PM
Is it possible to have the same public and private key pair that got generated by the algorithm ?  How is the algorithm generating public and private keys..

Theoreticaly, yes it is possible.
But practically, it is not possible because the chances are almost zero.
You could use the whole energy available on earth and wouldn't generate a private key which already has been generated. In fact you would have created < 1% of all possible private keys.

Private keys are not generated by any algorithm. A private key is just a 256 bit random number.
The public key is then calculated through multiplication on the eliptic curve (in bitcoins case: secp256k1).
The address is then derived by calculating the hash: RIPEMD-160(SHA256(public_key)).
target
legendary
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Re: what if two people generate the same private key ? Is that possible
June 04, 2018, 10:35:12 PM
#6
Quote from: Cryptocoinbob on June 04, 2018, 10:29:30 PM
Quote from: target on June 04, 2018, 10:25:26 PM
Quote from: walkerbitco on June 04, 2018, 10:21:29 PM
what if two people generate the same private key ? Is that possible

Even  if its possible then what will happen then? Its not like the  can hack each other.
Who would have know we two have same private kay? This is not a problem  wwe woth can have the same password either but I don't think anyone can actually see we have same passsword which is p@ssw0rd.

Is it possible to have the same public and private key pair that got generated by the algorithm ?  How is the algorithm generating public and private keys.. Do you know or can you share a link to study ?

I didn't say its possible and I didn't say that its true two address can have same private key. I just set out an example that its not going to be a problem if  there is the same private key. I just set an example that it wouldn't be a threat to security if there are two address having same private key. Don't ask me a link about a study of this. Its just my logic, you  use yours.
danielberryfy
newbie
Activity: 29
Merit: 0
Re: what if two people generate the same private key ? Is that possible
June 04, 2018, 10:32:28 PM
#5
Quote from: walkerbitco on June 04, 2018, 10:21:29 PM
what if two people generate the same private key ? Is that possible

theoretically possible, but not in reality ... The probability is very very low
Cryptocoinbob
newbie
Activity: 30
Merit: 0
Re: what if two people generate the same private key ? Is that possible
June 04, 2018, 10:29:30 PM
#4
Quote from: target on June 04, 2018, 10:25:26 PM
Quote from: walkerbitco on June 04, 2018, 10:21:29 PM
what if two people generate the same private key ? Is that possible

Even  if its possible then what will happen then? Its not like the  can hack each other.
Who would have know we two have same private kay? This is not a problem  wwe woth can have the same password either but I don't think anyone can actually see we have same passsword which is p@ssw0rd.

Is it possible to have the same public and private key pair that got generated by the algorithm ?  How is the algorithm generating public and private keys.. Do you know or can you share a link to study ?
target
legendary
Activity: 2282
Merit: 1041
Re: what if two people generate the same private key ? Is that possible
June 04, 2018, 10:25:26 PM
#3
Quote from: walkerbitco on June 04, 2018, 10:21:29 PM
what if two people generate the same private key ? Is that possible

Even  if its possible then what will happen then? Its not like the  can hack each other.
Who would have know we two have same private kay? This is not a problem  wwe woth can have the same password either but I don't think anyone can actually see we have same passsword which is p@ssw0rd. mnemonic phrase might be common.
Cryptocoinbob
newbie
Activity: 30
Merit: 0
Re: what if two people generate the same private key ? Is that possible
June 04, 2018, 10:24:08 PM
#2
Looking at the post, I thought "Can two people have the same DNA? "

So, I looked on google, and found that it is possible but very very very very rare.

https://www.nytimes.com/2008/03/11/health/11real.html


walkerbitco
newbie
Activity: 15
Merit: 0
Re: what if two people generate the same private key ? Is that possible
June 04, 2018, 10:21:29 PM
#1
what if two people generate the same private key ? Is that possible
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