Example Trustless NEAR Light Client Implementation

Overview

An implementation of a trustless NEAR light client (LC) in plonky2(https://github.com/0xPolygonZero/plonky2). Proves the finality of a block based on the existing final block of the previous epoch.

Block Integrity and Finality Proof

1. Operating Fields: The NEAR zk-light-client operates on several critical fields within the blockchain ecosystem. These fields include the validators, the next_bp_hash (next block producers' hash), and the block hash itself.

2. Formation of next_bp_hash: The next_bp_hash is a crucial component in this process. It is derived from the set of validators responsible for producing the next block. This hash serves as a cryptographic representation of the validators' identity and their role in the upcoming block production.

3. Calculation of the block hash: The block hash is then calculated based on the data of the current block. This data includes the next_bp_hash. By incorporating the next_bp_hash into the block hash calculation, there is a direct cryptographic link between the validators of the next block and the current block's integrity.

4. Core Idea: The core idea is to establish a traceable and verifiable chain of custody for block creation. By proving that the next_bp_hash (derived from the validators) is a part of the current block's data, which in turn is used to calculate the block's hash, a secure chain is formed. This chain ensures that each block is not only a product of its immediate data but also carries a cryptographic signature of its contextual environment, i.e., the validators for the next block.Therefore, verifying a block's authenticity involves confirming that the set of validators is valid (thus legitimizing the next_bp_hash) and ensuring that the block hash is correctly derived from the data, including this next_bp_hash.

defined set of validators ======> defined next_bp_hash ======> defined block hash

Figure: Illustrative Scheme for Block Proving.

Input parameters for proof generation

1. Block for which the proof is generated (epoch N) Example

2. Block of the previous epoch (epoch N-1) Example

3. List of block producers for epoch N Example

Near State Proofs

• Proof of Inclusion for the NEAR Blockchain involves identifying a specific data slot in a smart contract and verifying its contents.
• Upon any data mutation, a Merkle tree is constructed using code from the NEAR core, ensuring the data's integrity.
• This process confirms the accuracy of the data in the slot and checks that the corresponding Merkle root is recorded in the blockchain.
• The result of this verification is typically formatted to display key information like the data's key, value, state root, and associated block hash.
• This ensures the data's validity and its presence in a specific blockchain state.

Tip

Read the example here NEAR_STATE_PROOFS.md

Developed by Zpoken Cryptography Team