A popular Hong Kong cryptocurrency exchange, Gatecoin, announces its plans regarding SegWit2x hardfork. According to the company, it will not be supporting the upcoming SegWit2x (B2X) har fork in November "due to the lack of two-way transaction replay attack protection coded into this proposed software upgrade”.
— Gatecoin (@Gatecoin) 23 октября 2017 г.
As detailed by the exhchange, not supporting B2X means that Gatecoin will:
- NOT distribute any B2X to the clients
- NOT process any B2X sent to the Bitcoin wallet addresses
- NOT list any B2X coin on the exchange
Therefore, Gatecoin clients hoping to claim newly minted B2X coins equivalent to their Bitcoin holdings at the time of the hardfork, will need to withdraw their Bitcoin from the exchange at least 12 hours before the hardfork occurs at block 494,784 (expected sometime in November, exact date TBC).
We will however be running B2X nodes in case the software’s developers decide to add replay attack protection in the future.
The company also sheds light on the two-way transaction replay attack protection, that prevents you from “double spending” your coins after the hardfork. Thus, without replay protection, new transactions will be equally valid on both the Bitcoin blockchain and the B2X blockchain as they will be identical to one another. This means that any new Bitcoin or B2X transaction can be copied or “replayed” from one chain to the other, hence the term “replay attack.”
To prevent this from happening, B2X should update their software so that new transactions are valid on one chain but not the other. This would be known as replay attack protection. For instance, Bitcoin Cash successfully implemented this as part of their chain split in August and is why Gatecoin was able to support it.