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Because crypto-currencies are validating transactions by having them validated by the network as a whole, a group who controls more than 50% of the computing po

• gus_massa 8y ago
  You can't create fake transactions[1]. You can reject some valid transactions or reject all transactions freezing the network for some time, and also try to double spend your money. [1] The idea is that the miner just pick the last block and select a bunch of the current transactions and a random number and makes a hash of all of them. If the hash has enough zeros at the beginning then it is a new block and it is distributed to all the network. The other nodes of the network validate all the transactions and also that this bunch of transactions with this random number produce a hash that has enough zeros at the beginning. Any invalid transaction of a wrong random number make all the other nodes of the network ignore the fake block. Once the last block and the bunch of transactions are picked, the difficult part is selecting a random number that with them produces a has that has enough zeros at the beginning. So the mines must try, try, and retry with different random numbers until they are lucky (or someone else is lucky). They must try millions of millions of millions (gillons?) of times, because it's difficult to pick the correct one. This uses a lot of electricity to power the computer. The other people just validate with the lucky number, so it's much cheaper.