Before diving into the task, we recommend familiarizing yourself with the basics of the Cosmos SDK. An understanding of its key concepts and architecture will greatly aid in the successful completion of this assignment.
If you're new to the Cosmos SDK, you might find the following resources helpful:
We understand that getting started with Cosmos SDK can be complex within a limited timeframe but the task doesn't require to understand all the concepts. Our suggestion is to familiarize with the fundamental, especially messages and modules:
Typically a module can be seen as a smart contract in the context of a Cosmos chain, and a message, a state transition, like an external function.
Develop a prototype of a light client that operates on top of a blockchain. This blockchain should verify proofs of state or transactions without needing the complete external blockchain data.
The source code provided is based on Cosmos SDK and represents a blockchain named foochain. The main components
within foochain are two modules: foo and lightclient (located under x/ directory)
Purpose: The core responsibility of the lightclient module is to store data that facilitates the proof of
transaction data for an external chain. The data stored by this module can be used to verify the authenticity and
correctness of a transaction without needing the entire state of the external chain.
Key Functionality: The module exposes a method VerifyTx in x/lightclient/keeper/lightclient.go, which can be
used to verify a particular
transaction. VerifyTx signature has a Proof and TxData types. Both types are empty structs defined in
proto/foochain/lightclient/lightclient.proto.
Purpose:
The foo module acts as a utility module that leverages the capabilities of the lightclient module. It consumes the
verified transaction data provided by the lightclient module to execute various application-specific logic
pertaining to foochain.
Interactions:
In the provided setup, the foo module calls the VerifyTx method from the lightclient module to get the verified
transaction data, which it then uses for its operations.
The codebase has been structured to separate concerns, where the lightclient module handles the lower-level logic of
transaction verification, and the foo module uses this verification in higher-level application logic.
Transaction Verification:
Implement the VerifyTx Function: This is the heart of the light client operations. The exact structure and design
of Proof and TxData types are left to your discretion.
Header Management: Implement logic that facilitates the addition of headers into the blockchain store.
Create a test application that leverages the VerifyTx function to validate transactions.
When it comes to populating the system with test data, such as headers, proofs, and transactions, you have full flexibility. Whether you choose to manually source and store this data in files or develop a utility to autonomously retrieve headers and Merkle proofs from a blockchain, the approach is entirely up to you.
This project was scaffolded using the Ignite CLI. If you wish, you can download and utilize the tool to aid in adding new state variables, messages, and for testing with a local network. However, if you prefer, you are also welcome to implement everything manually and provide a Makefile for building, setting up the local network, and other related tasks. The choice is yours.
Note: version 0.27.2 should be used
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