Haseeb-Qureshi

Urkel Trees: An optimized and cryptographically provable key-value store for decentralized naming

Boyma Fahnbulleh (Handshake)

• Merkle Trees are great, but can we do better?
• Ethereum's Wish List on better Merkle Trees:
  • Wanted a key-value store for the state
  • Allow updates without having to reconstruct the entire tree
  • Has bounded depth
  • History independent: root hash doesn't depend on ordering among updates (i.e., commutative updates)

• Merkle Patricia Tree is basically a fancy radix hash tree

Haseeb-Qureshi

Transparent Succinct Arguments

Alessandro Chiesa (UC Berkeley, Starkware, Zcash)

What are succinct arguments?

• Proofs of computational integrity
• Game between prover and verifier
• Prover knows an input to a F(x) that would make it return y
• Prover could trivially prove this by providing x
  • This convinces the verifier for sure!
• Being able to convince the verifier of a true claim is the property of completeness

Haseeb-Qureshi

require 'faraday'

class PasswordCracker
  ALPHABET = (('a'..'z').to_a + ('0'..'9').to_a).shuffle
  SUBJECT = 'password'

  def initialize(api)
    @api = api
    @password = ''
  end

Haseeb-Qureshi

Fast Multiparty Threshold ECDSA with Fast Trustless Setup

Steven Goldfeder

Digital signatures authorize transactions in cryptocurrencies

• Alice's device, containing her private key, is a single point of failure

Multiparty authentication

• Instead of having a single device store your key material...
  • You can split it into multiple devices

• Designed your address as protected by multiple keys

Haseeb-Qureshi

interface Lender {
  function goWild() external;
}

contract FlashERC20 is ERC20 {
  using SafeMath for uint256;
  
  function flash(uint256 amount) external {
    balances[msg.sender] = balances[msg.sender].add(amount);
    Lender(msg.sender).goWild();

Haseeb-Qureshi

Ethereum 2.0 and beyond

Vitalik Buterin (Ethereum Foundation)

• Ethereum 2.0 spec pre-release
  • Released yesterday!
• Proof of stake and sharding have been part of the ETH roadmap since 2014
  • Started with Slasher in 2014, which is totally broken
  • But since then have made a lot of progress
  • Casper FFG devised and formally verified

• Sharding is now better specified

Haseeb-Qureshi

Cryptoeconomics Mental Model

Vitalik Buterin, Joseph Poon, Karl Floersch

What's new?

• Karl: A lot of recent progress in Plasma Cash.

• Vitalik: Ethereum core has basically had most of the hard problems essentially solved. Only a few details that need to be hammered out—more efficient Merkleization, how to rotate validator sets, etc.

• Joseph: how to coordinate inter-chain communication? How to coordinate faucets, airdrops, to enable different kinds of social coordination.

Haseeb-Qureshi

Arbitrum: Scalable, Private Smart Contracts

Ed Felten

Ethereum smart contracts

• Have issues with scalability:
  • Every miner needs to emulate every execution step for the VM
  • Thus, charges gas for those who want to advance state of VMs
    • To compensate miners
  • The complexity of contracts is capped by the global gas limit

• All contract code and data can only be public

Haseeb-Qureshi

Betting on Blockchain Consensus with Fantômette

Speaker: Sarah Azouvi

• Bitcoin vs Traditional Consensus
  • Bitcoin is open memberships, participants unknown
  • One message broadcast per round
  • Incentives are at the core of its security
  • High energy consumption!
  • Slow...
• Blockchain without PoW?

Haseeb-Qureshi

Quisquis: A New Design for Anonymous Cryptocurrencies

Speaker: Prastudy Fauzi

• Bitcoin and Anonymity
  • "Bitcoin is like Twitter for your bank account" — Ian Miers
• Current Anonymous Cryptocurrencies and Their Limitations
  • Dash, Monero, Zcash
  • What technologies do they use?
  • Tumblers (Dash), Ring signatures (Monero), SNARKs (Zcash)

• Questions you should ask yourself: