Bitcoin Forum

Can the BTCitcoins of a wallet be stolen just with the public key?

Example: I have 50 BTC in my wallet, any person very far from me asks for I sell them 50 BTC and they say me they need a POF (Prove of founds), so they ask for I send a small amount of btc, (can be 10,000 satoshis) for they check the wallet in blockchain and make sure I have the enough amount to sell.

I ask this because I have heard a wallet can be cleared just to have the public key and with to have sent satoshis previously.

Please let me to know and if is possible, technical examples why can exists the possibility this happens. Or technically why this cannot happend.

Thank you!

to put simply every single transaction in every single bitcoin block contains the public key inside them. there are lots of cases of address reuse even by the big services (eg. bitfinex cold storage has thousands of coins in it and is being reused), if it were possible to steal bitcoin by knowing just the public key all these funds would have been stolen already.

it is about how Elliptic Curve Cryptography[1] works. the process of getting the public key from private key is easy but the reverse is impossible. in other words it is a "one way function".

p.s. in order to prove you have bitcoin you don't have to send anything. you can sign a message[2] but the message has to be unique and have timestamp.

[1] https://en.wikipedia.org/wiki/Elliptic-curve_cryptography
[2] https://bitcointalk.org/index.php?topic=990345.0

Yes.  Absolutely. 

The Public Key is mathematically related to the Private Key by an algorithm.  If you get the Private Key, you can steal the Bitcoin.  Just work a little bit to discover the algorithm which converts the Public Key to the Private Key and you are totally golden.  First one to discover it is a millionaire!!!  But don't be greedy.   If others find out you did it, the whole system will get less valuable fast.

It's possible, but probably not with our current technology. Simply put, Bitcoin's cryptographic protocols were built in such a way that it would be almost completely impossible to crack for current computers. The same goes for pretty much every secure system out there.

That being said, the next generation of computers (https://www.technologyreview.com/s/609408/quantum-computers-pose-imminent-threat-to-bitcoin-security/) probably could.

Bitcoin has a decentralized system that can be seen by everyone, and if only in that way it would not be possible that bitcoin could be stolen as easily as you say.

This is impossible, public key is wallet address only.
For send bitcoin need private key and sign transaction.
TX can't sign without private key.

I've never heard that way, and I think stealing bitcoin can not be as easy as you say, and bitcoin does have a decentralized system and it does not matter.

That isn't possible. If the attacker does not have a private key from your wallet, he can not take possession of your bitcoins.

What I mean is if I send any amount of btc to somebody else, through the transaction can be a way.

I don´t know how to explain it, for example, if you send btc through that transaction any code or any script is given when a transaction is signed and sent.

No of course not.  ::)

If that were the case then none of us would have a penny. It is impossible. Don't let anyone without a clue or a bitcoin tell you different. I'll prove it. Anyone want some bitcoin? Here is the public key, whoever gets it can have it.

https://blockchain.info/address/1Q1fDcqMBFYFi6Qd6JDnRnNsRLwHBKtqwq

I mean when you send some fraction to somebody else. It has to be some way because when you send a transaction, your public key is connected with the private key.

Thank you Pooya87, well I don´t understand yet about that thing, to sign a message, I don´t know how it works, I will read and try to understand later. But check this answer about my thread. :)
https://bitcointalk.org/index.php?topic=3390337.msg35530458#msg35530458

To spend money or sign a message you must have a private key.  Each private key controls some number of public keys. As long as you use each public key only once it is very hard to determine an association between public keys and the private key that controls it.  But a public key alone is useless in accessing anyone's bitcoin.

The public key is not possible to get the private key, but the private key can generate the public key, so only knowing the address is not possible to get the BTC.

So, in the case a person use always the same public key? Is there any vulnerability.

Thank you, read this. https://bitcointalk.org/index.php?topic=3390337.msg35530458#msg35530458

I don't think this is possible because if it then there has been cases reported already. This is the reason why we have to keeo our private key hiden and secret so only the owner has access. I believe only a private key can access our bitcoin balance as simple as that.

It may allow someone to make an association between two public keys and reveal that they were created by the same wallet. But it will not help an attacker to get your bitcoin. Only the private key can do that.

This has never happened in the history of bitcoin and it would likely take billions of years if you were taking hundreds of guesses per second.

I think it not possible..but may not be impossible if someone finds a way to make a private key based on public address.If it happens,the bitcoin value will go down to zero

Oh that would be the least of your concerns. The encryption scheme used by bitcoin is used for all sorts of protection. Banks, databases, websites... It would be a free for all on stealing, and bitcoin would barely register compared with all the other assets protected by SHA.

i know it is hard to understand the technical part of it which is why i mentioned examples (bitfinex cold storage). here is the address https://blockchain.info/address/16rCmCmbuWDhPjWTrpQGaU3EPdZF7MTdUk and it contains 137,203 or $1.2 billion. and since it has made lots of transactions you can see its public key in all of those (outgoing) transactions. here is the public key:
02f0bb0774f61a63a610719f73c63f0019c0db62bdfc3682bc55f911538c766674
if it were possible, it would have been stolen already!

RawDog is just trolling here by saying "work a little bit"! it is impossible as of today and in the near future. maybe some day after 100 years with advancement we get enough computing power to find a reverse solution for it and break it but not any sooner. and if we get closer to something like that a simple fork can change bitcoin in a way to prevent it. you still have nothing to worry about, these things don't happen over night.

for example, years ago (2012) SHA1 was considered less secure and everyone slowly moved to other hashings to increase their security until it was no longer used for anything important (2013). finally after years that nobody used it anymore it was broken (last year - 2017) by putting a huge amount of computing power (roughly 110 years of computing from a single GPU for just one of the phases) in it by Google.

The statement is irony. I slowly believe in your thought but I think if it is possible then bitcoin already gone right now. Public keys have similarity in private keys but you cannot unlock or encrypt easily the algorithm provided by just using a public key. Even a mathematician and hacker will combine their knowledges, they can't solve and cracked bitcoins algorithm unless you are Satoshi Nakamoto.