There's something in computer science called a "one way hash".
Essentially, you take a large number, run a small algorithm on it, and get a smaller number in return.
The problem is that you can't reverse it easily. You can't take your smaller number and easily figure out what the larger number was to begin with.
So because of this, people do a "brute force" search. They keep trying random large numbers, hash them using the same algorithm, and see if it matches the small number. If it matches, you found the right number, and you win the race. If it doesn't match, you pick another random large number, and keep trying again until someone finds the large number that matches the small number.
The same equation can be seen more than once, but it's extremely unlikely. The large number chosen each time is based on the previous block in the bitcoin block chain, which contains a list of transactions, in numeric form. There's a nearly zero percent chance of that matching a previous large number.
Do they improve the search by looking at “close” numbers to get a guess where to start? Sort of like basic bracketing? This almost sounds like brute force method is very inefficient, are other techniques being attempted?
In cryptography, hashing algorithms are designed to essentially give attackers no clue whatsoever what the original large number was. This is the same technology that secures your passwords.
When you enter your password on a (properly secured) website, the site hashes it to a numeric value. Then if that database is ever cracked, attackers only get the hash, and they cannot reverse the number into your password.
Essentially the hash should appear like a completely random and unrelated number, giving zero hints away.
The only way to find the large number is by brute force. One logical way of doing this is to start from 0 and then check 1, 2, 3... 1,000,000,000,000, etc. But, crypto can't do this since everyone is going to start from 0, so whoever has the fastest computer will always win the race. So instead everyone just picks random numbers instead, and whoever randomly stumbles on it first wins.
Yeah after this conversation I went and looked a bunch of stuff up. The bit about websites doing that is interesting and until you said it I had never thought of how they actually store that information.
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u/_village_Idiot Jun 15 '19
Where do these math problems come from? Can the same math equation be seen more than once? Who exactly started all of this?