BCH bifurcation hard back: “replay attack” user self-help guide

On November 16th at 2:16 in the morning, BCH occurred in 556767th blocks of highly hard bifurcation, bifurcation of war ended, divided into BCH ABC and BCH SV two camps.

In the hard BCH ABC bifurcation, BCH and SV both sides are not “replay protection”. That is to say, the bifurcation, in theory, replay attacks will likely lead to zero and not force any party consensus collapse.

What is the “replay attack”

The traditional computer terminology, replay attack (Replay Attacks) also called replay attack, replay attack, refers to the attacker sends a destination host has received packets, to achieve the purpose of deception system. The replay attack may occur in any network communication process, is one of the Computer World Hacker common attack. Mainly used for identity authentication process.

In the block chain, replay attack (Replay Attacks) usually occur in the blockchain hard bifurcation, refers to “a chain of transactions in the other chain tend to be legitimate”.

A simple example can explain what is the “chain block replay attack”:

To a small A can not effectively identify payment (in this case, you can not determine which payment) of the Brewery Beer, when he put the show with the success of Alipay payment payment information to sales, sales staff to give him the beer. Then again the small A to show the last payment information to another salesman, the salesman gave him a beer. As long as the small A continue to show his payment information, you can get Everfount beer, the brewery is being replay attack, the loss of countless beer.

The BCH bifurcation hard, BCH by a chain into two chains, get support and continue to operate under the condition of the two chains, another out of the chain and the bifurcation of the assets of BSV is BCH, ABC and BCH SV are. Because of the lack of replay protection, bifurcation after if you leave it, let it grow, this time there will be such a situation: you trade in the SV chain, due to the same address, algorithm and transaction format, get the ABC chain to broadcast, there may be admitted to ABC chain, the same transaction operation. Once an attacker using this vulnerability, we charge provided in exchange (BCH SV), you can get extra BCH ABC.

This means that there is no BCH user assets replay protection has been exposed to the risk, more serious, will also lead to collapse and zero force consensus.

“Replay attack” origin: Ethernet square hard branch

7 2016 20 in the evening, the Ethernet 192 million square block height hard fork, produced a chain, and are called ETH chain and ETH Classic chain, the above tokens are called ETH and ETC.

The address and the private key algorithm both strands of the same transaction format are exactly the same, which is likely to result in a chain of transactions in the other chain is completely legal. So in which you initiated a chain of transactions, on the other chain to broadcast, may also be confirmed.

Because there is no prior plan, many people use this loophole, the ongoing ETH charge provided in exchange for additional ETC. “Replay” can be redefined in the blockchain world.

Influence of replay attacks, for users, the etheric square currently there are problems. Because ETH and ETC have good economic capacity, and if the user cannot solve their own operations may be replayed at the same time, he wants to sell an asset to retain another asset, or to separate, or only in exchange for assistance in order to achieve.

Response: the first separation retransaction

Since BCH has the bifurcation of without replay protection, is reproduced can not be avoided, so, in order to avoid losses, exchange and users are necessary before the new deal, the holdings of BCH ABC/BCH SV were isolated.

Let us look back two upgraded version of BCH: bitcoin ABC 0.18.2 and bitcoin SV 0.1.

The main change is the Abc0.18.2 protocol version adds two operation code OPcode, OP_CHECKDATASIG (CDS) and OP_CHECKDATASIGVERIFY (DSV); sorting sorting rules in transaction blocks from the topology (TTOR) into a canonical ordering (CTOR).

The main change is the SV0.1 protocol version restored the bitcoin four earlier operation codes OPCode, OP_MUL, OP_LSHIFT, OP_RSHIFT, OP_INVERT; delete each script 201 operation code restrictions; improve the block size limit to 128MB.

The two version update operation code, who already holds the BCH users, using the new OP code trading operations, should be separated and operating accounts more secure.

The separation of the most simple and effective way is in the 100 blocks of the split point, buy a little coinbase transactions from the mine pool UTXO, sent to your BCH wallet, and then all the disposable balance transferred to a new address. Only in a chain to do so once, you can completely separate.

Separation of two kinds of assets, the new OPCode you can use, not to have the new OPCode security risks in BCH on the chain caused by replay.

This aimpil (SECBIT) laboratory to remind the BCH holder and support ABC/BSV exchange, before the separation of you / your user BSV, to avoid losses replay, cautious use of the new OPCode in the transaction.

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