Bitgold come funziona machine
The block chain is a shared public ledger on which the entire Bitcoin network relies. All confirmed transactions are included in the block chain. This way, Bitcoin wallets can calculate their spendable balance and new transactions can be verified to be spending bitcoins that are actually owned by the spender. The integrity and the chronological order of the block chain are enforced with cryptography.
A transaction is a transfer of value between Bitcoin wallets that gets included in the block chain. Bitcoin wallets keep a secret piece of data called a private key or seed, which is used to sign transactions, providing a mathematical proof that they have come from the owner of the wallet. The signature also prevents the transaction from being altered by anybody once it has been issued. All transactions are broadcast between users and usually begin to be confirmed by the network in the following 10 minutes, through a process called mining.
Mining is a distributed consensus system that is used to confirm waiting transactions by including them in the block chain. It enforces a chronological order in the block chain, protects the neutrality of the network, and allows different computers to agree on the state of the system. To be confirmed, transactions must be packed in a block that fits very strict cryptographic rules that will be verified by the network.
These rules prevent previous blocks from being modified because doing so would invalidate all following blocks. Mining also creates the equivalent of a competitive lottery that prevents any individual from easily adding new blocks consecutively in the block chain. This way, no individuals can control what is included in the block chain or replace parts of the block chain to roll back their own spends.
No one person or computer has responsibility for these block chain updates; no miner has special status. The updates, like the authentication of new blocks, are provided by the network of bitcoin miners at large. Bitcoin also relies on cryptography. The computational problem is different for every block in the chain, and it involves a particular kind of algorithm called a hash function.
Like any function, a cryptographic hash function takes an input—a string of numbers and letters—and produces an output. But there are three things that set cryptographic hash functions apart:. The hash function that bitcoin relies on—called SHA, and developed by the US National Security Agency—always produces a string that is 64 characters long. You could run your name through that hash function, or the entire King James Bible.
Think of it like mixing paint. If you substitute light pink paint for regular pink paint in the example above, the result is still going to be pretty much the same purple , just a little lighter. But with hashes, a slight variation in the input results in a completely different output:. The proof-of-work problem that miners have to solve involves taking a hash of the contents of the block that they are working on—all of the transactions, some meta-data like a timestamp , and the reference to the previous block—plus a random number called a nonce.
Their goal is to find a hash that has at least a certain number of leading zeroes. That constraint is what makes the problem more or less difficult. More leading zeroes means fewer possible solutions, and more time required to solve the problem. Every 2, blocks roughly two weeks , that difficulty is reset.
If it took miners less than 10 minutes on average to solve those 2, blocks, then the difficulty is automatically increased. If it took longer, then the difficulty is decreased.
Miners search for an acceptable hash by choosing a nonce, running the hash function, and checking. When a miner is finally lucky enough to find a nonce that works, and wins the block, that nonce gets appended to the end of the block, along with the resulting hash. Her first step would be to go in and change the record for that transaction. Then, because she had modified the block, she would have to solve a new proof-of-work problem—find a new nonce—and do all of that computational work, all over again.
Again, due to the unpredictable nature of hash functions, making the slightest change to the original block means starting the proof of work from scratch. But unless the hacker has more computing power at her disposal than all other bitcoin miners combined, she could never catch up. She would always be at least six blocks behind, and her alternative chain would obviously be a counterfeit. She has to find a new one. The code that makes bitcoin mining possible is completely open-source, and developed by volunteers.
But the force that really makes the entire machine go is pure capitalistic competition. Every miner right now is racing to solve the same block simultaneously, but only the winner will get the prize. In a sense, everybody else was just burning electricity. Yet their presence in the network is critical. But it also solves another problem. It distributes new bitcoins in a relatively fair way—only those people who dedicate some effort to making bitcoin work get to enjoy the coins as they are created.
But because mining is a competitive enterprise, miners have come up with ways to gain an edge. One obvious way is by pooling resources. Your machine, right now, is actually working as part of a bitcoin mining collective that shares out the computational load. Your computer is not trying to solve the block, at least not immediately. It is chipping away at a cryptographic problem, using the input at the top of the screen and combining it with a nonce, then taking the hash to try to find a solution.
Solving that problem is a lot easier than solving the block itself, but doing so gets the pool closer to finding a winning nonce for the block. And the pool pays its members in bitcoins for every one of these easier problems they solve. If you did find a solution, then your bounty would go to Quartz, not you. This whole time you have been mining for us! We just wanted to make the strange and complex world of bitcoin a little easier to understand.
An earlier version of this article incorrectly stated that the long pink string of numbers and letters in the interactive at the top is the target output hash your computer is trying to find by running the mining script.