23. June 2018 The H IT 0 D ie meltdown of Bitcoin gold began on 16. May lunchtime: Criminal attacker could target die the main branch of the block chain, to make it undone transactions contained. The attack was the most vulnerable point of Bitcoin gold, to it in the same way at Bitcoin, all Bitcoin Forks and most other crypto currencies with decentralized block chain are. Bitcoin’s creator Satoshi Nakamoto described him already 2009: They carried out a so-called 51-percent attack, by bringing the majority of hash performance world under their control. In this way they could cheat traders of crypto currencies by several million dollars – and could you repeat any time. length comparison The sticking point of Bitcoin & Co.
is, that the block chain of crypto currencies continues autonomously decentralized and all miners.
The design looks explicitly no central instance before, in Miner could download the currently valid block Chain. Instead, the miners get out of the Bitcoin network, the longest known chain block.
The longest chain would also be theoretically the most recent: the difficulty level (Difficulty) is all 2016 Blocks adapted to, that it takes exactly two weeks, more 2016 to calculate blocks. So Bitcoin Bitcoin and gold are a regular block time of ten minutes. Is a block chain shorter than another, it is potentially several minutes older and outdated so. In practice, it happens occasionally, that two Miner find two different solutions for the currently sought Block almost simultaneously.
Then there are initially two valid, equally long block Chains, which differ only in the last block. Both spread simultaneously in the Bitcoin network, continues to operate so that a part of the mineral with the one and the rest with the other block Chain.
Which block chain prevails, depends, the block chain survived with most blocks – for which the two chains new blocks are first found, the other dies. In rare cases it is possible to miners, for both block chains to find additional blocks nearly simultaneously, then one speaks of branches. not 2015 about two solutions have been found for three consecutive blocks of the block chain Bitcoin, before the block 364000 brought the decision and let die the other branch. Absolute majority Should anyone bring the majority of the Miner a block chain under its control, it could soar to become sole ruler of the cryptocurrency: With 51Percent of hash performance and more he could be sure, in the long term to find more new blocks as the rest of the network. His block chain would be always longer than the rest Miner, whose branches would die regularly. Death of a branch of the block chain from, so all the blocks and transactions within it are irrelevant. It is, as if the transaction never took place, since they are no longer included in the currently valid block Chain. So the 51 percent attacker could choose, which transactions into account or completely destroy the cryptocurrency even, by only empty blocks published without transactions – which the trade completely would collapse and the currency would suddenly worthless.
A 51-percent attack is therefore the worst-case scenario each cryptocurrency with decentralized block Chain. Under Cover The attack on Bitcoin gold was not aimed at the destruction of the currency, but served, steal money: For this purpose, the crooks rented Miner, the very much more hash performance than the official Bitcoin Gold network possessed. Some talk of up to 170 Mega-Hashes pro Sekunde (MH/s), the criminals should have had available – while the public Miner network via well 30 possessed MH / s. So the criminals were able to control the cryptocurrency at will.
But instead of publishing the first new block immediately, after he was found, they could continue to operate with the newly found block and calculate successor blocks only the Miner their secret Farm, which in turn was not published. This created a secret branch of Bitcoin gold chain block, which was longer than the branch of the official block Chain.
At the same time they sold large amounts of public Bitcoin gold to dealers, However, blocked these transactions in the secret miners, so they were processed by foreign miners and part of the official branch of the block chain. Then the crooks sold the same, already sold Bitcoin gold to another dealer – but left this transaction process only by its own miners, who knew nothing of the first sale. Thus, the second sale was part of the secret block Chain. Double Spend Only now the crooks published their secret Block Chain. Since she was longer than the previously known, the formerly secret block chain was immediately as the only valid.
The other branch, containing the first sale of Bitcoin gold, died – and therefore the first sale of Bitcoin disappeared Gold, as if it had never existed. The perfidy was, that the crooks took up the second sale in their formerly secret Block Chain, the coins were thus officially already spent. Thus they prevented, that a trader could transfer a copy of the original transaction again into the Bitcoin network and yet still get his money. This game repeated the crooks in the period from 16. to 18.
May several times and captured, according to estimates 18 Million US dollars, before they stopped for no apparent reason. Partly were the secret branches 50 blocks long, so that even longer waiting periods were ineffective.
The damage have the dealer of crypto currencies, the somewhat paid, but ultimately not have received it. crash ahead? Frightening is also, that this attack had no impact on the price of cryptocurrency. Meanwhile, the average hash performance of the Bitcoin Gold Miner is about 25 MH / s fallen, so the crooks have it even easier even, to repeat the attack or wipe out Bitcoin gold at any time. Investors do not seem to be interested in this impending total loss, at press time, the market capitalization of Bitcoin gold was still around 500 Million US dollars. And not just Bitcoin gold is affected, also Bitcoin Cash and other crypto currencies with few miners are real threat: The hash performance of the Bitcoin Miner cash about is only ten percent of the hash output of Bitcoin Miner. If only ten percent of the bitcoin miners coordinated pivot on Bitcoin Cash, could it there the same attacks carried out as if Bitcoin gold – the damage would at a market capitalization of around 15 Billion dollars but greater by far.
Protect you can not front. The only antidote would, to expropriate the scammers by Hard Fork of the block chain again, as it Ethereum after DAO Hack did. But for that you would need a majority among the miners. ( )
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