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

// From: https://github.com/bitcoin/bitcoin/blob/master/src/chainparams.cpp

        vSeeds.emplace_back("seed.bitcoin.sipa.be"); // Pieter Wuille, only supports x1, x5, x9, and xd
        vSeeds.emplace_back("dnsseed.bluematt.me"); // Matt Corallo, only supports x9
        vSeeds.emplace_back("dnsseed.bitcoin.dashjr.org"); // Luke Dashjr
        vSeeds.emplace_back("seed.bitcoinstats.com"); // Christian Decker, supports x1 - xf
        vSeeds.emplace_back("seed.bitcoin.jonasschnelli.ch"); // Jonas Schnelli, only supports x1, x5, x9, and xd
        vSeeds.emplace_back("seed.btc.petertodd.org"); // Peter Todd, only supports x1, x5, x9, and xd
        vSeeds.emplace_back("seed.bitcoin.sprovoost.nl"); // Sjors Provoost
        vSeeds.emplace_back("dnsseed.emzy.de"); // Stephan Oeste

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

Zexe: Enabling Decentralized Private Computation

Speaker: Pratyush Mishra

• How can we do computing on distributed ledgers?
  • Many existing systems for smart contract execution
    • Ethereum, Tezos, EOS, etc.
  • They all work through re-computation—every party redundantly performs the computations to agree on state
  • This comes with scalability tradeoffs
    • Recomputing all of these programs is costly

• Weakest computers (e.g. cell phones) can't keep up recomputing all transactions

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

Formal verification: the road to complete security of smart contracts

Martin Lundfall (MakerDao)

• What is formal verification?
  • Process of specifying and verifying the behavior of programs
  • Specification: mathematical description of intended program behavior
  • Verification: operational semantics of a language -> spec -> proof
  • There are 4 different "flavors" of assurances that formal verification can provide
    • 1. Smart contract bytecode verification - "Full description of EVM behavior"

• What can happen over the course of one transaction?

Haseeb-Qureshi

Privacy-preserving Multi-hop Locks for Blockchain Scalability and Interoperability

Speaker: Pedro Monero-Sanchez

• Payment channels are a widely pursued layer 2 scaling solution
  • But they only solve for bidirectional payments (between the two parties who open the channel)
• What if we build a payment channel network?
  • Naive solution—every pair of parties (N^2) opens a channel with each other
    • But then we need to lock up an exorbitant amount of capital in all these channels
  • Instead, let's open a few channels for each party

• And rely on other intermediary channels to reach the intended receiver

Haseeb-Qureshi

New and Simple Consensus Algorithms for ThunderCore’s MainNet

Speaker: Elaine Shi

• Synchronous, with a change of partition tolerance
• State machine replication (e.g., blockchain consensus)
  • Requires safety (nothing bad ever happens), and liveness (eventually something good happens)
• Thunderella
  • If you don't know Thunderella, go look it up (check out the BPASE '18 talk)
• Wait, there's a flaw in Thunderella?!

• A confirmed transaction can be undone, even in a somewhat benign setting

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

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: