Why is it not very very easy to steal Bitcoin or any Cryptocurrency?

[sploxon]

A thought occurred to me the other day. Why is not just extremely easy for anyone to claim bitcoins at an address we already have the hash key for? If each address has a secret key associated with it.. And all these keys are stored somewhere (where? on the blockchain?) What's to stop me just searching through the whole blockchain for a match? I can make up a new key and compare it against all the existing keys, That's millions of chances per key I make up ? I do this for one month, Surely I must find loads of matches? What am I missing here? Thanks

And for wallets which I can restore with a string of words - Why can't I just try loads of different 12 word mnemonic strings surely after 1 million goes I will find somebody's wallet to restore? This doesn't seem very safe to me

[sploxon]

So there really isn't another layer of security? If I compare thousands of hashes in a day to the entire blockchain you're telling me that I won't ever find a match in a Week, a Month - a Year? With a super computer? Cheers

[777asianinvasian]

So there really isn't another layer of security? If I compare thousands of hashes in a day to the entire blockchain you're telling me that I won't ever find a match in a Week, a Month - a Year? With a super computer?

No there isn't and I am no tech guy but if you have private keys that are alphanumerical passwords and are what 16-32 cases long. That means that your probability of finding it is inbetween 16-32! (the ! is a probability thing) and those numbers are probably in the trillions if I had to guess. If you feel lucky enough you can find one in the trillions by all means go for it but you would spend forever. Your second point however is more concerning because a quantum computer is nothing like what we have seen and that IS a worry moving forward that needs to be addressed eventually by all coins in the crypto market imo.

[stompix]

I can make up a new key and compare it against all the existing keys, That's millions of chances per key I make up ? I do this for one month, Surely I must find loads of matches? What am I missing here? Thanks

Well, math and the laws of physics are against you...
This image is never going to get old.

And all these keys are stored somewhere (where? on the blockchain?) What's to stop me just searching through the whole blockchain for a match?

The keys are not stored in the chain. The blockchain is a ledger of the transactions.
I recommend you start reading https://en.bitcoin.it/wiki/Main_Page before you waste your life searching for a match.

That means that your probability of finding it is inbetween 16-32! (the ! is a probability thing) and those numbers are probably in the trillions if I had to guess. If you feel lucky enough you can find one in the trillions by all means go for it but you would spend forever.

One trillion is just a puny 2^40,  think more of 2^96 when you try to match private keys.

[dead_m92]

So there really isn't another layer of security? If I compare thousands of hashes in a day to the entire blockchain you're telling me that I won't ever find a match in a Week, a Month - a Year? With a super computer? Cheers

You are on the point, you can easily recover or just generate the seed or the 24-12 words.

But it is very difficult, because you need to generate them.
The only way that you are NEVER going to get access to a wallet is if that balance is stored on an exchange.

If you open another account on a different pc, they will get an email, just like you receive everytime that you made a withdraw/deposit or just a sell on localbitcoins.

That is why a lot of people are concerned about the Quantum computers, because they can generate the private keys.

[Coin-Keeper]

Without breaking down into a pure Mathematics post, just look at this using simple logic.  If you have a BTC address in a wallet (example Electrum) go ahead and bring up the private key for that address.  Now observe how long and highly scrambled it is.  Now just picture that you would EVER be able to randomly generate that number in your lifetime, remembering that as you generate your random keys you have to also use them to perform an analysis if there is a match out there.  While possible in theory it would more likely be lifetimes without ever getting a "hit".

[digaran]

You are not revealing your private key to the blockchain, you are signing your transaction and the process is encrypted by 256 SHA algorithm. you could try some other way like figuring out the first checksum of an address and then find how often the same checksum is repeated in Bitcoin addresses.
For e.g, if you could find out how many addresses start with 1Digaran and after that you need to see how many addresses have beggar after 1Digaran and then how many addresses have lowlife after 1Digaranbeggar, after that you need to find out how many addresses have needs1BTC, after that tobuyahouse.
(wait, did I just killed Bitcoin for the second time?) first time I killed it with my activity tokens.

[brusnika]

hey!! this occupation is completely useless, try to find to the key to the particular Bitcoin purse. If you are not the hacker and somebody  you are interested in, doesnt keep his privat keys of BTC wallet on the desktop. It is just waist of time.

[jlanzago]

You don't understand the nature of the blockchain. The keys are not "stored" somewhere where they can be hacked or obtained by someone as if they were banking passwords. There are not just "hashes".

[sploxon]

okay - So go back to the 12 word phrase thingy if you please,
Why can't I just attempt to restore thousands of times with various 12 words from the dictionary? I bet I would find something in a couple days, I might be wrong, But they just ask you for 12 words.. no address or anything? cheers for useful replies people

Also - If I sign up with the wallet hundred times I might see that some words appear more than others as a basis to start from - or just use the words given to me on my 100 accounts to hopefully crack some others?

--

Also #2 : Back to Bitcoin - It is true right that I can restore my wallet (whatever that means) from my Private key? I mean that's just one private key. So is it JUST down to possibility? Everyday that possibility gets less as more people join and more keys are made, I have bigger chance of Hitting a wallet with a random key? Is that correct or am I missing something.. I mean the 'keys' must be 'stored' somewhere? Otherwise what allows me to restore my wallet? Cheers

[dead_m92]

And yes, i said that you could just never steal bitcoins from an exchange because they have passwords, 2FFA,
 and a lot of other security meassures.

But for a paper wallet, or something that is not protected with a password or 2fa is much more easier to get it stoled than a wallet from a third party.

Without breaking down into a pure Mathematics post, just look at this using simple logic.  If you have a BTC address in a wallet (example Electrum) go ahead and bring up the private key for that address.  

If you use pure mathematics you are never going to get a private key.

Only quantum computers are going to be able to do that.

[sploxon]

You don't understand the nature of the blockchain. The keys are not "stored" somewhere where they can be hacked or obtained by someone as if they were banking passwords. There are not just "hashes".

Maybe you could explain a bit more from this point please Pal?

[BingoDog]

It's not ea easy because bitcoin system was build also with security system. Not everyone has the access to it because there are private keys there are numberless hashes to compare in blockchain. If this was easy then bitcoin system would function very bad for the users and they would feel very unsecure having and operating with bitcoin. But luckily I think bitcoin is one of the most secure system by design.

[fattyforhire]

Understand! Not just this whole system was created and exists as a decentralized cloud. For 7 years of the existence of bitcoin, not one person thought about the possibility of hacking. Such people even have a profession - hackers. And they definitely do not think as banal as the described process in this topic. Do not make others laugh.

[chimcoin]

I think it is not very easy to steal bitcoin because security has been a fundamental one for bitcoin since its development. On one hand, bitcoin itself is very difficult to hack or steal,  and that is largely due to the blockchain technology which supports it. As blockchain is constantly being reviewed by bitcoin users, hacks are unlikely. On the other hand, though, the fact that bitcoin itself is difficult to hack does not mean that it's necessarily a safe investment. There does exist potential for security risks at various stages of the trading process.
Note that Bitcoins are held in wallets and traded through digital currency exchanges like Coinbase. There are various security risks inherent in each of these two components. Developers are always improving wallet security making it difficult to steal people's coin and tokens.

[shacc]

all is about the private keys that help prevent loss of funds and other mishaps.
anny valid transaction bearing a valid signature will be accepted by the Bitcoin network. so any person in possession of a private key can create a valid transaction in bitcoin chain.
 and note well that someone knowing only your private key can steal from you.

[Yakamoto]

A thought occurred to me the other day. Why is not just extremely easy for anyone to claim bitcoins at an address we already have the hash key for? If each address has a secret key associated with it.. And all these keys are stored somewhere (where? on the blockchain?) What's to stop me just searching through the whole blockchain for a match? I can make up a new key and compare it against all the existing keys, That's millions of chances per key I make up ? I do this for one month, Surely I must find loads of matches? What am I missing here? Thanks

And for wallets which I can restore with a string of words - Why can't I just try loads of different 12 word mnemonic strings surely after 1 million goes I will find somebody's wallet to restore? This doesn't seem very safe to me

You could hypothetically do something like that, but I have a feeling that you're dramatically underestimating the amount of potential combinations that stem from the various private wallet codes. You have 72 different potential characters for each character in the wallet string, and you have, what, 32 of those? More than that? There's at least 2.8E20 combinations that can exist, and that's either a lot of guessing without having anything to show for it, or a LOT of computing power. There was a picture not too long ago describing how safe a wallet is.

[BCTBF]

If your bitcoin does not put in a safe place, then the hacker will be easy to steal your bitcoin, there are many cases that have occurred. I feel bitcoin can still be stolen by irresponsible people. In fact I personally have experienced it on my blockchain account. I installed a bitcoin game app and after 24 hours my email went off saying it asked for login verification in blockchain. I am still saved because I have secured my account well.

[gulliblehive]

I think it just comes down to mere probability that you'll actually 'stumble' upon a match due to the sheer number of possible combinations. Although I could be wrong?

[BlasterS]

The first reason I think is bitcoin is a virtual currency which there is no physical substance that subject in snatchers.
All IT experts and hackers are has capacity to steal this virtual currencies, unfortunately the company of bitcoin provides a high security to block this threats may happen.