Poseidon — Provable Fast Track Consensus by Partisia Blockchain

There are 7 proprietary innovations that deliver Partisia Blockchain’s complete Layer 1+2 Blockchain. In this blog, we present the first innovative feature — the consensus model — we call it, Poseidon.

For an overview of all of the 7 features see the Zeus blog. We present each of the 7 innovations with a unique post leading up to TGE on May 31, 2022.

Poseidon — Provable Fast Track Consensus

A core requirement for any blockchain is to establish trustworthy consensus about the shared distributed ledger holding information like transactions ordering and smart contracts. Only this way can blockchain replace intermediators in the economy and simplify coordination of tasks, data and trades. Establishing consensus in distributed computing systems has been studied for decades. Although there is no perfect game theoretical solution, the most trusted approach is the so-called Byzantine Fault Tolerance model (BFT). The name comes from the “Byzantine generals problems” where independent generals need to establish common knowledge to succeed. The main problem with naïve BFT is that it is too slow and hampers scalability. Partisia Blockchain, however, provides scalability with BFT through an Eager FastTrack consensus model.

On Partisia Blockchain, transactions are added to the ledger via immediate block creation and executed node by node immediately after signing. Consensus is established in the P2P network where signatures are propagated and aggregated. When a node achieves signatures from ⅔ of all nodes or more, a Proof-of-Justification (PoJ) is established, and the node moves on to evaluate the next block immediately. PoJ also finalizes the transactions in the previous block. Since this process happens as fast as information travels through the P2P network, we call it lightning fast finalization. In rare cases, the FastTrack approach may fail to reach consensus. If this happens, the protocol reset the blockchain through a full BFT style consensus and restart the FastTrack consensus, as illustrated below. This way, the consensus protocol achieves finalization among ⅔ of all nodes as fast as possible, while still backed by a BFT style consensus.

Combined with sharding, scalability is complete as a reset on one shard happens independent of the other shards, but more about that in the next blog on “Iris — complete sharding”.

Another core problem solved by Partisia Blockchain is to ensure that the validators actually construct and validate transactions. This is a general problem for validation based consensus like Proof-of-Stake, which was solved in the Proof-of-Work protocol where miners don’t get paid if they work on a wrong version of the blockchain. A validator on the Partisia Blockchain, however, has to construct a cryptographic proof prior to signing a block. The cryptographic proof is node-specific and proves that the node has signed the executed version of the blockchain.

For more details, please checkout the yellow paper and the software documentation.

Please let us know what you think and stay tuned for the next blog post about our Sharding technology, called Iris.

Thank you to everyone in our community for your support!

Partisia Blockchain Team