What’s the core of Blockd?
Blockd takes advantage of a blockchain’s Replace-By-Fee (RBF) protocol. RBF allows a user to replace an unconfirmed transaction with another with the same nonce as long as the replacement has a higher transaction fee. While blockchains like Ethereum do not have an explicit RBF protocol (unlike Bitcoin), I refer to theirs as an implicit RBF protocol. Bitcoin’s RBF is hardcoded into their system, requiring that transactions being generated must specifically opt-in, whereas Ethereum’s implicit RBF is a purely game theoretical system wherein miners choose between two transactions sent from the same account with the same nonce based on which has a higher gas price.
The other core strategy of (the first iteration of) Blockd is the use of pre-signed transactions. By having users generate and sign transactions but not broadcast them to the network immediately, it allows Blockd to broadcast the transactions at will, executing the wishes of the user whenever necessary. This maintains complete trustlessness because the only transaction that may happen from a user’s account is one they approve.
How does Blockd work on the inside?
Blockd consists of a frontend in which users sign their transactions or submit their transactions and select the criteria on when Blockd should block a transaction. This user data is then sent to our centralized database. No private account information is stored, only signed transactions.
Once saved, our monitor begins monitoring unconfirmed transactions for one originating from the user’s account. If one is seen, the system checks the user’s criteria to see whether it should be allowed, then acts accordingly.
If the transaction must be blocked, the system begins by checking which gas prices the user’s pre-signed transactions have. This is important because the blocker transaction must be sent with a higher gas price than the currently pending transaction.
If a pre-signed transaction with a higher gas price is found, the system immediately broadcasts it to the network. The system then continuously checks whether that transaction has succeeded or whether more action is needed.
What other products are on the roadmap?
The first addition to Blockd will be token support. Blockd currently only supports saving Ether balances but any ERC20 token may be supported. However, Ether and ERC20 tokens aren’t the only thing Blockd can protect.
We’ll have similar systems for dapps, whether that includes the owner signing a pause transaction or our service having special approval to withdraw/pause/save a dapp, in which we track pending transactions to the dapp, analyze their effects, and act accordingly. There is enormous security benefit from this system.
A security breach or experimentation could be spotted and avoided on a dapp. This can include everything from alerting the developer if a user is making suspicious transactions, to enacting a full shutdown if a transaction is analyzed that would withdraw all contents of the contract. In a world with so many targets attractive to hackers, this system is an absolute necessity.
The last (not necessarily in the roadmap but in discussion) big branching out, of course, is Blockd moving to more blockchains. There are other blockchains that use the same or similar RBF protocols and Blockd protocols currently in development may be able to secure almost any blockchain.
In an industry with security concerns greater than most any other, Blockd does and will provide more security than has ever before been available.