Overview

Plasma Next is a Zero-Knowledge Proofs (ZKP) based Plasma that eliminate the need for online requirement of users. In Plasma Next, transfers from senders to recipients are facilitated through an operator. Here are the detailed mechanisms:

Payment Channel

The core of Plasma Next is its payment channel, a protocol for executing off-chain transfers between two parties. When making a transfer, both parties sign a structure called a payment that records their balances. Traditionally, both parties needed to continuously monitor the blockchain to prevent fraud. Plasma Next eliminates the online requirement for the user by focusing on one-way payments from the user to the operator.

Airdrop

To facilitate payments from the operator to users, Plasma Next employs airdrops. The operator can distribute funds to multiple users at once using a Merkle Tree, significantly reducing on-chain costs. This process includes the operator creating a ZKP to prove that funds for the airdrop have already been deposited, allowing users to confidently withdraw their funds at any time. Furthermore, users can prove the aggregate amount of multiple airdrops using ZKP and withdraw them at a constant gas cost. Additionally, the funds from airdrops can be deposited off-chain into a payment channel.

ZKPTLC (Zero-Knowledge Proof Time-Lock Contract)

The transfer from the sender to the operator via the payment channel, and from the operator to the recipient via airdrop, must be conducted atomically. If the transfer is not executed atomically, there is a potential for loss either by the sender or the operator. Plasma Next addresses this atomicity by introducing ZKPTLC (Zero Knowledge Proof Time-Lock Contract). ZKPTLC specifies additional conditions for the settlement of payments in a smart contract. By default, Plasma Next utilizes ZKPTLC to verify the evidence of airdrop from the operator to the recipient. This ensures that if the operator does not perform the airdrop to the recipient, the transfer from the sender to the operator cannot be settled, preventing the operator from receiving money from the sender.