Platform Chain

Distributed ledger for tracking state transitions

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Overview

The platform chain is the Drive component responsible for replicating the platform state across all masternodes participating in the network. Masternodes operate this Proof of Service (PoSe) chain to provide layer 2 consensus and support Dash Platform-specific requirements without impacting layer 1 functionality. Although the platform chain can read from the Dash layer 1 core blockchain, the core blockchain is not dependent on it or aware of it.

Details

Evolution of design

Early designs of Drive were based on using on the layer 1 core blockchain and IPFS to replicate layer 2 data. As the design matured, a number of challenges led to a re-evaluation of how to efficiently secure, propagate, and finalize this data. Ultimately, meeting the requirements for a trustless, decentralized system led to choosing a blockchain-based solution over some seemingly obvious choices that work fine in a centralized setting.

Characteristics

In order to support Dash Platform's performance requirements, the platform chain has the following design characteristics:

• Relies on masternode Proof of Service, not miner Proof of Work (PoW)
• Hosted exclusively on masternodes
• Uses a practical Byzantine Fault Tolerance (pBFT) consensus algorithm
• Has a deterministic fee structure
• Provides fast (< 10 seconds) and absolute block finality (no reorgs)

Blocks and Transitions

Similar to transactions on the Dash core chain, state transitions are aggregated and put into blocks periodically on the platform chain. Each block has a header that points back to the previous block, thus forming a chain of blocks that is shared among all masternodes. The platform's pBFT consensus algorithm is responsible for ordering the state transitions into a block and then committing the block. As soon as a block is accepted by a ⅔ + 1 majority of validators, it becomes final and cannot be changed. Thus, the platform chain is not susceptible to blockchain reorganizations.