To be able to accept both networks, a new block must contain evidence of work (proof of work). Proof of work requires diggers looking for some nonce, that the contents of block hashes (cryptographic hash function) and the nonce, the results create a smaller number of the network's target (the smaller the number of target the higher the degree of difficulty). In other words: Proof of work is very easy for computer validation, but extremely time consuming to create. Diggers have tried many different nonce before achieving the required network difficult.
Every block was created in 2016 (approximately 14 days), the difficulty was automatically tune network based on the ability of the entire network, with the aim is to keep the time between the newly created block is 10 minutes. From March 2014 to March 2015, the average number of excavators nonce hash to try before you create a new volume has increased from 16.4 billion to 200.5 billion billion billion.
Systematic proof of work activities, together with the re-sequencing data blocks when new blocks including hash of the old block, makes changes blockchain extremely difficult, as the attacker needs to change all the rear block a block to the change accepted. This requires the attacker to have over 50% of the total processing power Blockchain network. New blocks are constantly being created, and the difficulty of changing one block over time increases with the number of blocks to change (also known as the authenticity of a block - confirmations) increases. [19]
In fact, the miner would typically engage in large dug mine to gather the computing power of the excavator members to increase the frequency that mines create a new block, and then the money will be divided members agreed in digging mines. The mining has created a series of specialized technology to dig Bitcoin. Currently, Bitcoin system most effective training using dedicated integrated circuits ASIC because we handle arithmetic faster computer processors (including the graphics card) but using less more power. [20]
