From signing to Superfinality.

TL;DR

• Bitcoin-Secure Sequencers build Hemi blocks.
• Proof-of-Proof miners secure these blocks to Bitcoin.
• Bitcoin Finality Governors facilitate communication with Bitcoin and relay Bitcoin finality to Hemi.
• Publishers update Ethereum on what’s happening.
• Challengers scan for misbehavior.

So you’ve signed a transaction. Now what?

After a transaction is signed, it goes to a Bitcoin-Secure Sequencer node, or BSS. The BSS’s job is to gather, sequence, and package transactions into a block.

Soon, a BSS node will create a new keystone block on top, and will send a notification to the Bitcoin Finality Governor (BFG) node of the new keystone. At this point, imagine the BFG as a student sitting between two friends passing notes in class. The BFG tells Proof-of-Proof miners there’s a new block to secure to Bitcoin. “Pssst. This is for you.”

The PoP miners pull data from the block and create a Proof-of-Proof transaction. Now the miners need a hand: “Put this proof on the Bitcoin blockchain so it knows the transactions up to this keystone have taken place.”

The BFG dutifully propagates the Bitcoin PoP transactions to the Bitcoin network. Then it waits to hear back. “Hey, Bitcoin, did you get my message?”

As Bitcoin miners create new blocks, this PoP transaction is soon included in the chain. When it is, the BFG updates its view of Hemi chain publication to Bitcoin, which it can use to serve Bitcoin Finality information to third-party applications like exchanges and wallets.

Independently, each BSS node is connected to the Bitcoin network via P2P, and will have also heard about this new Bitcoin block. Now, when a BSS node creates a new Hemi block, it will include a reference to this new Bitcoin block, and update the Bitcoin node running inside its Hemi Virtual Machine (hVM) before passing the new Hemi block along to other BSS nodes who will do the same. Now, each BSS node has full visibility of Hemi’s new PoP publications to Bitcoin which will be used for protection if a network fork is ever proposed.

How will all this get passed along to Ethereum? Publishers. These nodes are rewarded in native tokens for communicating the network’s consensus data to smart contracts on Ethereum. If they send bad intel, a Challenger, who is also incentivized with native tokens, will call them out and prove their misbehavior. The protocol will slash the Publisher’s stake, and those native tokens will go to the Challenger.

Unless an attacker creates an alternate Hemi chain and publishes it to Bitcoin, Hemi blocks become final after just nine Bitcoin blocks. After that, an attacker would need to simultaneously control at least 51% of Bitcoin’s computing power and Hemi’s native consensus power to alter them. Thanks to the additive nature of PoP, Hemi transactions reach Superfinality not long after, making an attack even harder. In short, your transaction has gone through and won’t be reversed.

To see how you can get started making your own decentralized apps, read the whitepaper and the relevant documentation or stop by the team’s Discord.