Is it possible to guess a privkey?

[Sir_lagsalot]

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?

[1714917648]

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[domob]

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.

[DannyHamilton]

As the title asks, is it possible to guess a privkey/generate an existing wallet's privkey?

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 quite interested about how mining for a bitcoin address works.

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.

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),

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.

or is it some other kind of algorithm?

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.

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.

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

Assuming I was lucky enough to mine the exact same address, could I get the privkey?

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.

[Hugroll]

Assuming I was lucky enough to mine the exact same address, could I get the privkey?

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

[shorena]

Assuming I was lucky enough to mine the exact same address, could I get the privkey?

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

[traderbit]

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.

[RodeoX]

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.

[BurtW]

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.

[DannyHamilton]

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.
- snip -

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?"

[Mirdude]

Would take a hell of a long time tbh!

[h0w8rd]

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.

[RodeoX]

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.
- snip -

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?"

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

[jaydipmodhwadia]

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*

[virtualx]

As the title asks, is it possible to guess a privkey/generate an existing wallet's privkey?

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.

[h0w8rd]

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.

[DannyHamilton]

This search space is so huge its larger than finding one genome in the entire human genome.

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.

[DannyHamilton]

anybody can guess the private key,

No. They can't.

it just takes too long to do it.

Which is why they can't.

when I was explaining BTC to my girlfriend and friends, I say is impossible for anyone to crack a wallet

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

the time it take is longer than the universe itself,

Much, much longer.

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.

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.

[lottoshares]

As the title asks, is it possible to guess a privkey/generate an existing wallet's privkey?

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.

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.

[Remember remember the 5th of November]

@DannyHamilton

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

[Jeremycoin]

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.