Quote from: knightkon on January 07, 2016, 01:38:57 AM

Quote from: shorena on January 03, 2016, 09:00:41 AM

Quote from: xmax on January 03, 2016, 03:41:07 AM

I keep seeing all these posts that someone can hack my wallet. First I did not think that this could be done? If it can be done, how can I prevent it from happening? Does my wallet need to be online in order for them to be able to hack it or can they still hack a paper wallet?

It is possible that someone can just guess or brute force your private key. The chance however is so small you might as well call it impossible. Its as likely as someone winning the lottery several times in a row and will for all we know never happen as long as the sun is still burning.

Other than that it mostly depends on the way you use your machine. As AllInCrypto said if the machine that you use to control your wallet is infected by malware, its easy for the attacker to spend your coins. Its however not "easy" to infect a modern, well updated system, unless you do something to help the malware. Commonly bitcoin related malware will require you to execute it yourself, so be careful what you download and use.

Just reading through and have to question how someone could brute force your private key? I of coarse do not understand what the private key is nor do I understand what brute force means, but the thread interested me.

A private key is just a number. So lets assume the possible numbers for a private key are between 1 and 4. I dont know your private key, but I just test all 4. Thats a brute force attack. I just try all possible combinations and see if I hit the jackpot. Of course with bitcoin the number is significantly bigger. There are 2²⁵⁶ = 115792089237316195423570985008687907853269984665640564039457584007913129639936 possible private keys. Roughly one for every 1000 atoms in the known universe[1]. This makes guessing your private key possible with infinite time and resources. We dont have infinite time and resources though, so we can consider it impossible.

[1] http://www.wolframalpha.com/input/?i=2%5E256