Last weekend on Bitcoin Cash was carried out a planned attack during which unknown attackers have used the vulnerability of the plasticity of the transaction. This was stated by Chinese mining pool ViaBTC.
The plasticity of the transaction due to the cryptographic trick, which changes a signature of a transaction, but without changing what this signature means. This can be done even without the secret key used to create the original signature. With regard to cryptocurrency, this means that anybody can take any transaction from p2p networks and to substitute original signature equivalent that would be valid. This new signature will continue to reflect the same data that was originally signed, and still can pass the test using the original public key. The result of the transaction, it will not change, but since everything will look different, will completely change txid — the transaction ID.
The plasticity of the transaction leads to two main problems. First, it interferes with the operation of software which uses the txid to verify the confirmed transactions. But more importantly, the plasticity of the transaction limits the potential use of all kinds of extended use of bitcoin, built on the unconfirmed transactions by using the txid, for example, Lightning Network.
It is this attack, according to ViaBTC, and was implemented on a network of Bitcoin Cash, the result of which was temporarily suspended withdrawals.
It is noteworthy that the problem of the plasticity of the transactions decides the Protocol Segregated Witness, which this month must be activated in the network of bitcoin. We will remind that earlier supporters of the Bitcoin Cash, arguing that his intention to run an alternative circuit, said including that SegWit is not as important as, for example, a larger block size, and the problem can be solved in other ways.
As for the alleged attack, with her, judging by the fact that after some time ViaBTC returned to normal operation, managed to save. However, this is not the only problems for the first week of its existence faces a Bitcoin Cash.
Creating new blocks the new cryptocurrency at this early stage of its existence is not yet much slower than in the original network. Although the difficulty Bitcoin Cash declined slightly in the last 24 hours in the network was produced just 81 block against the 146 blocks in the bitcoin network. And taking into account the considerably fallen price, it also negatively affects the profitability of mining.
In recent days to Cash Bitcoin mining was joined by two more pool – BitcoinClub and Supr Nova. However, the latter not only sent a very small capacity, but also accompanied your first mined block quite intriguing Coinbase message:
In addition, as seen in the chart below, over 80% Hasrat network Bitcoin Cash continues to account for some "unknown" pool.
Thus, according to Bitcoin.com he is not related to the already mentioned MC Pool from Hong Kong, and it makes publishing to assume that this unknown pool may be involved in the network.
On a number of utverjdenii seen the problem is that a acting with malice miner deliberately prevents further reduction of complexity.
"There is a pattern in which someone with a large hasraton produces two blocks at intervals of a few minutes every time should be the allocation of a challenge," wrote one user of the r/btc.
Another user in the comments confirms that also watched the following scene in the moments when "honest" miners slowed down the work or took a break for 12 hours in order to lower the difficulty.
"I saw the same in real time. We had almost 12 hours, not more than ViaBTC 25PH power, the last block was found in 339 minutes, and then – BAM! – we get a new unit after 13 minutes. This is the third time we go over the mark at 11.5 hours."
However, as of Monday morning, price BCH, falling on the eve of nearly $200, went up again: at the time of publication (09:15 Kyiv / Moscow) the average rate is $244.58.
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