Tomer Weiss
May 23, 2018 · 9 min read

bitemBassy Hackathon 2018

The article was written in collaboration with Leonid Beder, VP R&D of Orbs and one of the Hackathon Judges.

The hackathon of the Bitcoin embassy is the main and biggest event of the organization.

This year, as an ambassador of the Bitcoin embassy, I got the opportunity to lead the organizational efforts of the event alongside fellow embassy’s volunteers Sarah Wiesner, Roei Levav, Oria Halevi and Lior Zysman. The preparations for the event took several months, while in their peak, two months before the hackathon itself, we conducted a registration and learning meeting which included workshops on Lightning Network and developing smart contracts on Ethereum. Additionally, 90 developers joined forces to become 20 separate teams. The majority of the participants didn’t know each other beforehand and included new and veteran members of the community. What characterized the participants as a whole was their passion for decentralized technology and their desire to contribute to this ecosystem.

The Goal:

The goal of the hackathon was to bring new and veteran members of the community together, into this existing decentralized technology ecosystem. Together, they executed meaningful projects that will make bitcoin, and the rest of decentralized protocols, scalable and accessible to future bitcoin users.

The rules:

  • 31 hours of hacking.
  • Teams of 1–6 participants are allowed. All team members had to attend the Hackathon preparation meetup.
  • Teams weren’t allowed to begin their projects until the competition officially begins. Teams were allowed to use your own projects if they were online in the past two months, and could’ve built on top of previous projects whose code exists online.
  • The aim was create a useful and usable hacks with a working POC (or better). Any open blockchain was ok, but the the organizers reserved the right to reject projects ideas that didn’t align with the core design values of the judicial staff.
  • Teams had to use Git to track their code and progress in a publicly open repository. Teams that wouldn’t open their repos were disqualified.
  • Teams had the full ownership of everything they built and are free to do with it as they wish.

The Judges:

The hackathon was judged by Meni Rosenfeld the chairman of the Israeli bitcoin association, Ofer Rotem an angel investor in the crypto field, Nadav Ivgi one of the senior official programmers of bitcoin around the world and the founder of Bitrated, Ken Timsit the head of the ConsenSys office in Paris, Yuval Rouach the CEO of Bits of Gold, Udi Wertheimer a world renowned bitcoin developer, Sarah Wiesner a Bitcoin Ambassador and Leonid Beder the VP R&D of Orbs.

The Judging Criteria

  • Demo / Executions — 55%
  • Technology — 13%
  • Contribution to the Decentralized Ecosystem — 13%
  • UX — 13%
  • Liberté — 6%

The last category is a major characteristic of the bitcoin embassy. Bitcoin can be a part of a more liberated, free and peaceful society. Our goal, in this criterion, was to examine whether or not the project supports or promotes this idea.

The Winners

Top 3 + ConsenSys winners curated by Leonid Beder, one of the Hackathon Judges and VP R&D of Orbs.

All the competing teams were great and all of them should be proud of what they were able to achieve in these two days.

The winners selection wasn’t especially hard and we’ve spent more than a couple of hours of inspecting and evaluating the different projects.

… and the winners are:

Drum roll

1st Place: Team “BrainSeed”, 1 BTC Prize

The winning team set the goal to improve both the security and usability of brainwallets.

BrainSeed aims to improve on top of regular brainwallets in the following ways:

These days, almost every application is using BIP32/BIP39/BIP44 standards for wallet generation. For backup, the (extended) master private key is most commonly serialized to a either 12 or 24 words, which can be later used to restore it. Even though 12/24 words are much easier to remember than a 128/256 bit key, it’d be still extremely challenging to do so. After all, we keep forgetting our passwords — how are we supposed to remember 12/24 nonsensical words?

Instead, BrainSeed only asks you to remember:

  • Only 6 words.
  • A simple salt (which can be your email, for all sakes and purposes).

It also allows you to select a difficulty setting of either: Normal (3 seconds), Hard (30 seconds), and Brutal (1 Hour), which you don’t need to remembers, since it’s encoded in a version byte.

How does it compare to BIP32 in terms of security?

Instead of performing 2048 key stretching iterations, BrainSeed utilizes scrypt to perform much stronger key stretching instead, translating the difficulties above to:

  1. Normal (3 seconds): N=1048576, r=8, p=1 (can take a few seconds to hash).
  2. Hard (30 seconds): N=4194304, r=6, p=4 (can a couple of minutes to hash).
  3. Brutal (1 Hour): N=4194304, r=600, p=4 (can take a couple of hours to hash).
  4. This technique will make brute force seed cracking extremely hard, since for every guessing attempt, the attacker would also need to perform the lengthy key stretching (e.g., imagine having to spend one hour for every attempt).

You can read more about scrypt parameters here.

The aforementioned dictionary is also designed to include easier to remember words (such as nouns and verbs), and shouldn’t contain words that will lose meaning over the years (e.g., in 2100 the words “lawyer” and “banker”, hopefully, will disappear from the vocabulary). This makes remembering the words even easier.

In order to compensate for selecting fewer words (6 words, compared to the usual 12/24 words), BrainSeed can consider to extend the popular 2048 words dictionary with additional words (in their POC, the team were only using a dictionary 1024 words). There are about 170,000 words in the English dictionary, so it’d be trivial to find additional easy to remember words.

In overall, we really liked the elegance and the simplicity of the idea, as well as a really smooth and intuitive UX.

(left to right): The winners, Alon Go, Matan Shapira, and Ori Newman

2nd Place: Team “KaPow” — 0.5 BTC Prize

A 500tech team which have created a Chrome Extension provided one-click payments utilizing the Lightning Network. For example, merchants could embed a tiny JavaScript in their web applications, which could then automatically convert a Bitcoin “buy” button to a Lightning Network powered payment. The interaction itself is very similar to MetaMask.

Team “KaPow” at work

3rd Place: Team “Lighnting Dragons”, 0.3 BTC Prize

The project implements a Texas hold ’em poker game over the Lightning Network. The innovation of their project is that while the game is conducted by a server, only the funds of the current hand is ever at (a counter-party) risk — the chip stack of users are always in their possession. Moreover, the randomness of each hand is collected from all active participants and is verifiably fair.

Alon Elmaliah presents the project LNPoker — A Bitcoin Lightning Network Poker game

Special ConsenSys Award Winner:

ConsenSys was founded by Joseph Lubin, a co-founder of Ethereum, in 2014, as a start-up venture production studio. Today it is one of the largest blockchain technology companies globally, with 900 staff in 28 countries.

The company believes in the Israeli unique ecosystem and chose to establish here a new operation center. As part of the preparation and getting to know the community event, ConsenSys chose to help funding the Bitcoin embassy Hackathon 2018. The company awarded a 2 Ether worth special prize for the Ethereum project and an opportunity to present the winning project to the CEO of the company, Joe Lubin.

Team “HashBounties” — The ConsenSys Award Winner


The team has implemented a crowd-sourced cryptographic hash cracking and were even able to launch it as a web service at:

Basically, it goes like this: imagine that you have a hash whose pre-image you terribly require (let’s say, its pre-image is a private key you need). Using HashBounties Smart . Contract, you could create a bounty, which will automatically release the funds to whoever can present you with the right pre-image (in which case, it would be now visible on the blockchain and you should be quick to utilize it).

Haim Bender presents the project

Team Yuki — The judges’ honorable award.


The judges’ honorable award was presented to Team Yuki — Yona Segev, Gitai Zach, Lior Or and Yuki Dvir. The team members are community veterans and co-founders of the embassy. They have decided to examine some interesting applications of the Lightning Network, which could improve itcoin adoption. As part of their research, they reached to various conclusions about how the Lightning Network can support a model of financial conflict resolution, multi-party smart contracts implementation, currency stabilization and even implementation of a decentralized oracle (an external party that provides data to the system). In favour of the hackathon, the team have chosen to focus on a specific aspect, and have presented a case where multiple entities want to establish gates with potential customers who wish to pay in Bitcoin, yet are not interested to be exposed to its volatility. In order to tackle the problem, the team have built a smart decentralized contract on the Lightning Network for fiat hedging (i.e., a stable coin). The smart contract enables separate parties to interact, while holding conflicting positions: one is looking to receive fiat while the other is interested in hodling to Bitcoin. An open and decentralized Lightning channel would regularly offset the arbitrage (i.e., rapid settlement) resulting due to the volatility of the currency. By doing so, it would hedge the risk in which a business, that wants to accept bitcoin, is exposed to. The team were able to reproduce this interaction, while simulating Bitcoin prices, as a proof of concept In conclusion, even though the Lightning Network is still in its early days,it was certainly shown that Lightning applications, of similar kind, are a meaningful step towards bitcoin mainstream adoption.

Team Yuki at work

We will continue our efforts for the community and the decentralized technology:

It is the first time I am taking part in organizing the hackathon. Turns out it is not a simple task at all. The job included raising sponsors, reaching the participants, building a schedule for the event, working with suppliers, budget management etc. however, a fun task nonetheless. It was a satisfying opportunity to be a part of a platform that generated friendships and innovative technology. It was exciting to see how a bunch of people came together to become separate groups that converged applicable ideas, which took shape and became working applications that promotes bitcoin and its ecosystem.

The bitcoin embassy and its volunteers will continue their endeavors for the community and its decentralized technology. Stay updated and visit our website.

Many thank to all the sponsors that contribute to the event and helped to make it happen: Bits of Gold, Orbs, Proton, Blockstream, ConsenSys, Yerugo, Zen Protocol, Edmond De Rothschild bank, chiliz, Blox, Wemark, Israeli Bitcoin Association & ZAG-S&W law firm

Bitcoin emBassy TLV

The Bitcoin emBassy TLV is a grassroots mission to offer a…

Bitcoin emBassy TLV

The Bitcoin emBassy TLV is a grassroots mission to offer a location where the community and all the enthusiasts can use, and organizes a variety of events and projects for the community. At the Bitcoin emBassy TLV all are welcome to share and talk about the decentralized digital

Tomer Weiss

Written by

Bitcoin emBassy TLV

The Bitcoin emBassy TLV is a grassroots mission to offer a location where the community and all the enthusiasts can use, and organizes a variety of events and projects for the community. At the Bitcoin emBassy TLV all are welcome to share and talk about the decentralized digital