Bitcoin Forum

As the title asks, is it possible to guess a privkey/generate an existing wallet's privkey? I'm quite interested about how mining for a bitcoin address works. Is it kind of the same thing as mining a block, guessing combinations of numbers and letters (the privkey) to unlock the code (wallet address), or is it some other kind of algorithm?

I've used vanity miner before, and I've tried guessing an existing address, but according do vanitygen, it takes more than a billion years on average to solve. Assuming I was lucky enough to mine the exact same address, could I get the privkey?

Yes, in theory.  Note however that you provided the actual answer yourself:  The chance is so vanishingly small that it is, for all practical purposes, simply impossible.

That depends.  If the private key that you are attempting to "guess" was generated from a non-random source (such as a passphrase or faulty random number generator) and you know something about how it was generated, then it may be possible to guess or generate the same key.


I'm not sure what you mean when you say "mining for a bitcoin address".  That isn't really a commonly understood concept, so it probably works in whatever way you want to define it since you're the one using the phrase.


That would be known as a "brute-force" search for the private key.  It is a waste of time and money to attempt such a thing.  You could run a million computers for a million years and you still wouldn't randomly generate the private key for any address spcifically chosen ahead of time.


If a private key is generated in some non-random manner, and you know something about how it was generated, then you could limit the search space based on your knowledge.  This would allow you to build an algorithm around what you know about how it was generated.


Yes.  Much more than a billion years.  It isn't going to happen.


Yes, if you got the exact same address, then you would have one of the 7.9 X 10²⁸ (on average) working private keys for that address.

wait im not quite sure i understand, are you saying that every bitcoin address has more than 1 private key associated with it? I've always thought it was 1private key that links to 1 address

That is correct. There are 2²⁵⁶ private keys with 2²⁵⁶ public keys. The public key is hashed with ripemd160(sha256(pubkey)). Ripemd160 is limited to 2¹⁶⁰ possible solutions thus[1] there are 2¹⁶⁰ possible addresses with 2²⁵⁶ private keys or 2²⁵⁶/2¹⁶⁰ = 2⁹⁶ private keys per address. 2⁹⁶ ~7.9*10²⁸

[1] under some minor assumptions like even distribution

Everything is possible so i think guessing a private key is possible too.
But that could be the rarest case ever because there are lots of space to guess.
As shorena says the number is very huge so the probability to guess the correct private key are near zero.

Of course, watch me. Is your private key 1EHba6Q4Jz2uvNExL497mE43ikXhwF6kNm ?

Now just keep guessing until you guess correctly. Note that you should also start training your children to guess. This will likely take billions of years.

Yes, this is pedantic, but only because up thread was a bit more technical and your statement may cause some confusion:

1EHba6Q4Jz2uvNExL497mE43ikXhwF6kNm is not a private key, it is a Bitcoin address. 

As described above there are about 2^{256 - 160} = 2⁹⁶ public/private key pairs that will map to this specific Bitcoin address.

Actually...

It's not even a bitcoin address.  It's just a random string of characters that starts with a 1.

He might as well have said:

"Is your private key 1a2b3c?"

Would take a hell of a long time tbh!

Yes you can guess a Private Key, it's just a matter of time.

if you want to guess a privet key to a specific address, then it's just a matter of more time.

In my defense I thought he might be tricking me with an unusual private key.  :D
LOL, No, I read right past it and just plopped down a string for joke purposes.

To my understandings, I don't think even IBM Watson would be able to crack a privkey.
Quite frankly, its clever the way the addresses were made.
I thank Satoshi
*Preach*

In theory yes, but in practice the chance is so low that you can be certain it won't happen in your lifespan. This comes down to the search space being enormous. This search space is so huge its larger than finding one genome in the entire human genome.

anybody can guess the private key, it just takes too long to do it.

when I was explaining BTC to my girlfriend and friends, I say is impossible for anyone to crack a wallet, the time it take is longer than the universe itself, when I say "but" (there is the remote change, that's next to nothing) and they just don't feel safe there is some chance it could be hacked, and turned away from bitcoin.

Yes.  But that's a bit extreme.

It's sort of like saying that the visible universe is larger than a water molecule.  It's true, but as a comparison it really doesn't really tell you much about how big the visible universe is.

There are less than 25,000 human protein-coding genes.  There are approximately 7,300,000,000 humans on the planet.

That's 25,000 * 7,300,000,000 = 1.8 X 10¹⁴ total human genes on the planet (including all the duplicates that children get from their living ancestors).

Meanwhile there are 1.46 X 10⁴⁸ different potential bitcoin addresses.

That means that if you had 1 billion different bitcoin addresses for each and every human gene in existence in a living human, you still wouldn't even be close to finding a working private key for a given bitcoin address.

The average human being is made up of approximately 37.2 X 10¹² living cells.

That means that if you cut up all the living human cells on the planet, and extracted all the genes from every cell, and had 1 billion different addresses for each and every gene from each and every cell...

37.2 X 10¹² * 7.3 X 10⁹ * 25.0 X 10³ * 1 X 10⁹ = 6.79 X 10³⁶

You still wouldn't have even 1% of 1% of a chance of having found a working private key for a given bitcoin address.

If you repeated that same process on a million planets that were all populated with 7.3 billion humans just like us, you'd have 4.96 X 10⁴³. You still wouldn't have a 1% of 1% chance of having found a working private key for a given bitcoin address.

No. They can't.


Which is why they can't.


Assuming that the addresses are generated from a sufficient source of entropy, that is correct.


Much, much longer.


That's because you gave them bad information and mis-led them into believing the wrong thing.  There is not a "remote chance".  It won't happen.

Blockchain.info briefly generated private keys using a non-random source due to a programming bug. An honest programmer has a computer running which constantly scans the network for such vulnerable private keys, and transferred the coins controlled by them to his own secure address. He returned them to blockchain.info with an explanation of the programming error it had made that left them vulnerable to theft.

@DannyHamilton

I am astonished by the number of times you have replied to these kinds of threads. Anyone else would've lost their mind.

Yes it is, it just like crackin' a password. But it will take a long long long time to do it, because private key has so many characters in it.

The short answer is, "The earth will no longer exist by the time you guess a private key."

Here's the long answer.

https://i.imgur.com/fYFBsqp.jpg

i once asked the same question.
one answer is missing here:
nothing easier than that. this has already be done. have a look at: http://directory.io

edit: read carefully  ::)

Yes, it is possible but a bitcoin address of just so long it souls take you a few trillion trillion trillion years, if I remember correctly. O don't think humans have even existed for that long.... Maybe we'll be able to goes a private key when Quantum computers come out though :-/


Sorry if this is a little off topic, but how do you change your name?

The sane answer is ....... "NO"  :D

Theoratically yes.. its possible..
.. but its not worth the time trying.. you probably wouldn't guess the right private key in your entire life.

In theoretically it should be but practically it is not possible not for now but even for a decade from now.

Quick Spin on the question to anyone who feels obliged to answer,

If I created an Altcoin, and used the same algorithm (secpk256, i think) to generate the pub/priv key pairs, if I sent coins to an existing address on the bitcoin network, for example,one of Satoshi's, would the private key be the same for that address on the altcoin blockchain? i.e. would satoshi be able to spend these coins assuming he was aware of this?

thank in advance

Was

Yep!

excellent, thank you.

CLAM distribut(s|ed) its coins that way.

you can create address.


then guess it.


probability is 100% key is same :D

but you're not richer
sad

come to my house

take my pc

copy my key

you guessed it :D

congratulation you stole my funds

chance is 100% when I sleep

when awake i beat you up

clam?

It's an "altcoin".  As a rule I generally avoid all altcoins, so I don't know a lot about it, but you can read a thread about it here if you like:
https://bitcointalk.org/index.php?topic=623147.0

It is possible. Just don't waste your time.

The initial distribution of CLAMs is interesting. Basically, if you owned Bitcoins at a certain point in time then you own the corresponding CLAMs, all you have to do is claim them.

Sorry, I did not want to derail the thread with this. They also did(?) this for litecoin and dogecoin. I say did with a questionmark because there recently was a big discussion whether the dev should fork CLAM to change this behaviour. I did not follow the coin for a while though, so ...

Don't worry, as stated before, private keys are strongly encrypted and would take quite some time even for supercomputers to decrypt. Don't worry, your coins are safe.

Wow, now that I think about it, that makes an awful lot of sense. But hashing is a lot more random, on average it will be impossible, but even a lemon could guess a privkey first try.

If there isn't some RNG collision... I had experience with one same address in btc core and on blockchain.info Probably got so lucky=) No import\export of course. Generated with period 1 month+. This year. When developing exchange of BitMoney. No proofs but it happened.

So...

P.S. Oh i see there was some bug on blockchain.info, but how it could coicide with btc core?

Basically you have a better chance of winning the lottery AND being hit by lightning than guessing the correct private key for a given address. As pointed about in a prior post, the math can change drastically if a faulty RNG was used.