We’ve got some good news, and we’ve got some bad news.
Bad news first: Following a hard fork of a blockchain, there is a risk of what is known as a replay attack if the blockchain does not implement replay protection on the fork itself.
The good news is that there is an opportunity to insulate against replay attacks by going through a process called replay protection.
While there is not one single kind of replay protection process, the concept and tools for post-fork replay protection are getting better all the time.
What is a replay attack?
Following a blockchain hard fork, two ledgers that both contain historic transaction and public signature information exist.
For instance, following the bitcoin/bitcoin cash hard fork, there were two publically auditable chains both containing copies of the same information from confirmed bitcoin transactions prior to the split.
A replay attack in the crypto context is when someone copies and uses signature information from one blockchain to perform transactions on the other blockchain without the knowledge or consent of the original signature holder.
In simple terms, the attacker is duplicating or “replaying” one transaction on the other compatible blockchain.
This form of attack can result in the loss of assets. So, in order to reduce fraud and security issues following forks, it’s important to understand how to add replay protection to a crypto wallet.
What is replay protection?
Replay protection is a method of adding extra information to a blockchain transaction that essentially makes the transaction only compatible with that ledger. (It’s kind of like a blockchain version of the blue verified check mark on Twitter).
Replay protection is not automatically added to assets that are stored in wallets during the forking process. So following a fork, crypto holders interested in adding replay protection need to go through a transaction process that usually requires moving their assets through a wallet that does support replay protection. After that, the assets can be moved back to secure storage or preferred platform.
In the instance of the bitcoin/bitcoin cash hard fork, the team supporting bitcoin cash created a wallet to support replay protection and interested users could move their assets there to make them incompatible with the legacy bitcoin chain.
Adding replay protection to existing assets can in itself be a risky proposition because involves moving assets around, so proceed with caution.
What this means for Abra users
There have already been a number of significant hard forks in the crypto space. Forking is a useful governance tool and helps promote forward growth and innovation.
At the same time, hard forks also present turbulence that sometimes requires crypto users to perform some maintenance, or upgrade functions.
So far, Abra has not provided replay protection for assets inside our wallet. Instead, we direct Abra users to third-party tools that are specifically designed and built to perform the function of adding reply protection to recently forked blockchains.
As mentioned earlier, adding replay protection does require moving assets and should be done only after careful research, testing, and verification.