In a previous article we talked about the Alert key retirement plan, the retirement plan originally included releasing the private key to the public but this was only done recently. Any node running Bitcoin 0.12.x or more should have the alert system disable, while this is an ancient version of Bitcoin, about 4% of the current network is still vulnerable.
This made the Bitcoin Core developers create a final alert that overrides any previous alert and shows a warning message to all vulnerable nodes for wich an update is required. Unfortunately this didn’t turn out to be an optimal solution as this alert itself can be cancelled if another alert was to arrive at the node first. There were also fears that some Altcoins could still have the Alert system integrated into their code as a lot of them are just Bitcoin forks, upon further investigation it was found that only a small amount of altcoins on github are vulnerable, and almost all of them are abandoned anyway. Bitcoin developers also offered Altcoin developers a patch that can fix most issues regarding the Alert System, if they still wish to use it in their coins.
The Bitcoin community has been recently talking about disclosing the Alert Key, a system that was used by Satoshi Nakamoto in the starting days of Bitcoin as a network wide alert for important updates and network events, but as the developer circle of Bitcoin increased it was noticed that this system was a source of centralization as holders of the alert key can use it at any time to send out dangerous alerts that could disrupt the whole network.
The Alert system was deprecated in late 2016 with the release of bitcoin 0.12.1+ but the Alert key was never disclosed, this Alert system may still be used on different Altcoins forked from Bitcoin and so there was a call to all developers to immediately deprecate the system if it wasn’t already.