As Jayendra Madaram, a final year student from Hyderabad, I've long been immersed in the crypto space, primarily focusing on Ethereum and Web3 technologies. However, my journey took an unexpected and exciting turn when I was introduced to the Summer of Bitcoin 2024 internship program by my friend, Ayeman Mahamad. This opportunity opened a new chapter in my blockchain journey, allowing me to dive deep into the world of Bitcoin and contribute to groundbreaking projects.

The Selection Process

The Summer of Bitcoin (SOB) 2024 was highly competitive, with over 5,000 applicants from across the globe vying for spots. Against these odds, both Ayeman and I were thrilled to be selected. This achievement marked the beginning of an intense and rewarding experience.

Our initial phase was structured around weekly Friday sessions, where we delved into "Grokking Bitcoin" and explored fundamental Bitcoin concepts. These sessions were comprehensive, covering crucial topics such as Taproot

• SegWit

• Transaction structures

• Wallet technologies

• Block composition

• Coinbase transactions

• Proof of Work consensus

• And many more..

The program emphasized consistent engagement, requiring a minimum 75% attendance. This structure ensured we remained committed and made the most of every learning opportunity. The supportive community of like-minded Bitcoiners we encountered during these sessions was invaluable, pushing us to excel in every meet.

The Mini Bitcoin Miner Challenge

After successfully navigating the initial learning phase, we faced our first significant challenge: building a mini Bitcoin miner within a month. The objective was to create a block from given transactions, optimizing for the highest fee collection within a specified space.

For this task, I chose to work with Go, leveraging the btcd library maintained by the Lightning Network team. This decision proved crucial, as it allowed me to dive deep into production-grade Bitcoin code. After three intense days of coding and studying the btcd codebase, I successfully built a mini miner that exceeded expectations.

Key aspects of my implementation included:

• Use of SQLite3 for efficient data management

• Optimized algorithms for transaction loading and block building

• Comprehensive documentation and benchmarking results

My hard work paid off, resulting in a score of 110 out of 100, far surpassing the passing score of 60. This achievement was a significant confidence booster and validated my growing expertise in Bitcoin development.

For those interested in the technical details, I've open-sourced my implementation on GitHub: Summer of Bitcoin 2024 Code Challenge - Jayendra Madaram

The repository includes:

• A quick setup guide

• Detailed implementation explanations

• Workflow breakdowns for transaction loading, block building, and mining

• Rationale for using SQLite and its implementation

• Benchmarking results and a comprehensive score card

Choosing a Project

With renewed confidence from the mini miner challenge, I began exploring potential projects for the main internship phase. After careful consideration, I identified three top-tier organizations and projects:

1. Braidpool: A decentralized mining pool implementing the FROST scheme and UHPO transactions

2. CoinSwap: A privacy-enhancing swapping mechanism based on atomic swaps

3. python-bitcoin-utils: A Python library for Bitcoin operations, needing block parsing functionality

Braidpool particularly caught my attention due to its innovative approach. The project involved implementing eltoo-style UHPO (Unspent Hasher PayOut) transactions, similar to those used in the Lightning Network.

CoinSwap was also appealing, as it aligned with my previous experience in building a decentralized exchange based on atomic swaps.

For each project, I crafted detailed proposals:

• Braidpool Proposal

• CoinSwap Proposal

The Braidpool project required an additional competency test: implementing Taproot transactions in Rust. I successfully completed this challenge, further strengthening my proposal.

The Braidpool Project

After an anxious wait, I was ecstatic to learn that I had been selected for the Braidpool project. I immediately began collaborating with my mentor, diving deep into the project's goals and technical requirements.

Braidpool is a decentralized mining pool for Bitcoin, utilizing a short-lived Directed Acyclic Graph (DAG)-based layer-1 blockchain for producing Bitcoin blocks. It aims to decentralize share accounting, payout, and transaction selection.

My primary focus has been on implementing the Unspent Hasher PayOut (UHPO) mechanism, which aims to:

1. Reward all miners for their share of Proof of Work contributed

2. Scale sub-linearly with the number of participating miners

3. Allow miners to cash out unilaterally without requiring permission

The UHPO mechanism involves three main transaction types:

1. Coinbase Tx: Included by miners in their block templates

2. Payout Update Tx: Spends the previous confirmed payout update transaction and the latest coinbase transaction

3. Payout Settlement Tx: Spends the single output from the payout update transaction, with a time lock mechanism

My Contributions

Throughout my internship, I've made significant progress on the Braidpool project:

1. Initiated the project by thoroughly studying eltoo-style UHPO transactions

2. Successfully implemented UHPO transactions in Bitcoin DSL, a Ruby-based language developed by my mentor

3. Contributed the UHPO transaction implementation to the official Bitcoin-DSL repository, which was reviewed and merged

4. Developed a prototype SPEC Rust crate for UHPO transactions

5. Created and obtained review for a comprehensive specification document

6. Completed a full implementation of UHPO transactions within the Rust crate

7. Achieved partial code review and merger of the crate, specifically for the PayoutUpdate component

8. Finalized the implementation of PayoutSettlement, pending review and merge

9. Developed unit and integration tests for the entire crate

10. Prepared integration tests, awaiting review and merger

Looking Ahead

As I continue my internship, I'm excited to further refine and expand the UHPO implementation. My next steps include:

• Submitting pull requests for the remaining components of the crate

• Collaborating with the team to integrate my work into the larger Braidpool ecosystem

• Continuing to learn and adapt to the evolving needs of the project

This Summer of Bitcoin 2024 internship has been an incredible journey of growth, learning, and contribution. It has not only deepened my understanding of Bitcoin and blockchain technology but also allowed me to work on cutting-edge projects that have the potential to reshape the mining landscape.

I'm grateful for this opportunity and the guidance of my mentors - Adi Shankara, Stratospher, and Anmol Sharma. Their support, along with the collaborative spirit of the Bitcoin community, has been instrumental in my progress.

As I look to the future, I'm excited about the potential impact of projects like Braidpool and the continued evolution of Bitcoin. This internship has reinforced my passion for decentralized technologies and their potential to create a more open and accessible financial system for all.