Week 3 was the DeFi week and we were tasked with learning the real-world applications of Ethereum.

During the week, we were tasked with constructing a minimum viable decentralized exchange (DEX), which involved gaining insight into how liquidity pools maintain their liquidity using the curve function. By adding reserves to the pools, we were able to determine the number of tokens that could be exchanged for a particular token, and the curve function ensured that the liquidity pool remained solvent. For further information on the DEX, refer to the uniswap-solidity resource.

https://sepolia.etherscan.io/address/0x6a60210936E1C4dee2F421DA7ede5087bb631c80

https://bright-existence.surge.sh/

The second challenge familiarizes us with the blockchain trilemma, a significant issue in the world of blockchains. A trilemma refers to a scenario in which three options are available, but only two of them can be accomplished simultaneously at best. The blockchain trilemma comprises three options: security, scalability, and decentralization.

State channels really excel as a scaling solution in cases where a fixed set of participants want to exchange value-for-service at high frequency. Building the state channel application introduces all the core aspects of such layer 2 solutions. Building an application where a client/user could get off-the-cuff services in exchange for payment only for the services received was a great way to see these solutions in action. The challenge also urged me to look into other L2 solutions and how those compared to state channels.

https://sepolia.etherscan.io/address/0xF7916C2784ee17baA3ED0530071219384A4A809C

https://lowly-prison.surge.sh/

Week 4 was about understanding how multisig wallets and SVG NFTs work.

Typically, we process transactions directly on-chain, but this being a shared wallet with multiple addresses, we use Off-Chain Signature-Based Multi-Sig-Wallet. The process of a multisig wallet works by requiring multiple signatures from a set of predetermined addresses, and if any one of these signatures is missing, the transaction will not be able to go through. The contract will keep track of transactions in an array of structs and owners will confirm or reject each one.

https://www.alchemy.com/best/multisig-wallets

The contract uses recover() to retrieve the public addresses and verify the signatures. It also has duplicateGuard which avoid any duplicate entries from the signers.

https://github.com/scaffold-eth/scaffold-eth-challenges/tree/challenge-5-multisig

The objective of this task involved designing On-Chain SVG NFTs. Typically, NFTs are stored on IPFS, meaning that solely the link is saved on the blockchain while the metadata is kept on IPFS.

By examining the tokenURI of the NFT contract, we can observe this. The information in On-Chain SVG NFTs is entirely kept on the blockchain within the smart contract. Rather than a link, the tokenURI provides encoded json data that contains SVG information that can be shown in a browser.

https://github.com/scaffold-eth/scaffold-eth-challenges/tree/challenge-6-svg-nft

Working on speedrunethereum taught me a great deal about the potential of blockchain technology and how it can be applied to real-world scenarios. Overall, my experience with speedrunethereum was both educational and rewarding, and I look forward to applying the knowledge I gained to future projects in the blockchain space.

That’s all for this week. See you all in the build phase!

A little late to the party, but I just wrapped up my next week at the ETHIndia Fellowship. This week we had to complete the Token Vendor Challenge and the Dice Game Challenge of speedrunethereum.

Challenge 2: 🏵 Token Vendor

In this task, we made a decentralized, digital currency. And a vendor contract that basically deals with the buying and selling of this token. This challenge strengthened my understanding of ownership and transfer of ether / ERC20 tokens between contract and user addresses.

The first step in the challenge was to create the YourToken.sol contract, which inherits the ERC20 token standard and is responsible for minting 1000(*10**18) tokens for the Vendor.sol contract. On the YourToken contract, we could now use all of the ERC20 contract functions.

The second step is to write the Vendor.sol contract - the buyTokens() public function allows anyone to purchase the token in exchange for ETH by invoking the yourToken.transfer() function. The withdraw() function allows the contract's owner to withdraw the entire ETH balance of the Vendor contract.

The approve() pattern in ERC20 is another important pattern learned from this challenge. When a user needs to sell their tokens to the Vendor, they cannot simply send them and receive ether in exchange. They must first approve the Vendor contract before they can sell these tokens to the Vendor in exchange for ether.

This challenge was a great way to brush up on the ERC20 token standards, especially the approve pattern. These fundamentals are critical for understanding and writing DeFi contracts.

https://exciting-system.surge.sh/

Challenge 3: 🎲 Dice Game

The challenge was to exploit the randomization feature of the Dice contract so that we win every single time. Dice Game is a contract that allows users to roll the dice to try and win the prize. Players who roll either a 0, 1, or 2 will win the current prize amount.

We had to create a rigged contract that only calls a roll from the Dice Game contract when the player is certain to win. Predictable randomness is a challenge because the contracts are immutable and have real value. We were able to exploit the dice game contract by using the same randomness logic and only throwing winning rolls.

In real-world applications, this problem is solved in one of two ways; produce randomness off-chain or use chainlink VRF (Verifiable Random Function).

https://harsh-chin.surge.sh/

That’s about my second week at the fellowship. Thanks for sticking till the end. Let’s see what the next 6 weeks have for us.

Adios 👋

I was selected for the program, and let me tell you, I was ecstatic! The first week began with an onboarding session where I met the other fellows, a diverse group of individuals from movie geeks to music aficionados. I couldn't wait to get to know each of them and learn more about the technology we would be exploring.

The first four weeks of the cohort are dedicated to making our knowledge of solidity stronger. We started off the first week with 2 projects from the speedrunethereum challenge. The first project was an NFT minting smart contract, which was more of an intro on how to set up scaffold-eth and how to deploy the smart contracts.

Simple NFT Example:

https://straight-property.surge.sh/

https://goerli.etherscan.io/address/0xD9C3Ea65DFD0071e680Af284bdE488B2Fd2f2aAd

The second project was a Decentralized Staking app. With the help provided, I was able to write the contract which successfully passed all the tests. I accomplished my weekly Ethereum speedrun challenges, and I was thrilled with my achievements.

🥩 Decentralized Staking App:

https://wary-silver.surge.sh/

https://goerli.etherscan.io/address/0xd7899ad3e4c206065fe2f603897a7e0c8c13cd4e

So far, the ETHIndia Fellowship has been an incredible learning journey, and I am excited to continue exploring decentralized technologies and honing my skills in Solidity. I can hardly wait to see what the next seven weeks have in store for me.

I am grateful for the opportunity to learn about decentralised technologies and network with participants from across India. I'm excited to see where the future of web3 will take me.