The Six Grand Challenges

IC3 has many projects underway to address what we identify as six “Grand Challenges” to widespread blockchain adoption. A number of examples are given below.

The six Grand Challenges outlined above serve as a motivation and a project map for the following IC3 projects.

Projects

Honey BadgerBFT: The Honey Badger of BFT Protocols
Support Grand Challenges:
Scaling and Performance

HoneyBadgerBFT is the first practical asynchronous BFT protocol, which guarantees liveness without making any timing assumptions. We base our solution on a novel atomic broadcast protocol that achieves optimal asymptotic efficiency. We present an implementation and experimental results to show our system can achieve throughput of tens of thousands of transactions per second, and scales to over a hundred nodes on a wide area network. We even conduct BFT experiments over Tor, without needing to tune any parameters. Unlike the alternatives, HoneyBadgerBFT simply does not care about the underlying network. For more info, please see our paper (https://eprint.iacr.org/2016/199.pdf).

Teechain
Support Grand Challenges:
Scaling and Performance

Teechain is the first asynchronous second layer payment network that allows users to execute immediate payments while not requiring parties to constantly monitor the blockchain. Teechain leverages trusted execution environments (TEEs) and uses a new variant of chain replication to ensure security against TEE compromise and side-channel attacks. Teechain achieves at least 33x better throughput than other existing payment networks. For more info, please see https://www.teechain.network.

Charlotte
Support Grand Challenges:
Scaling and Performance

Charlotte is a new open framework for building parallel, interoperable blockchainsystems. It supports a variety of consensus mechanisms including proof of work as well as more classic distributed consensus protocols.

VyperFlow
Support Grand Challenges:
Correctness by Design and Construction

VyperFlow is a new programming language for blockchain-based smart contracts based on Vyper. It incorporates information flow control into its type system to maintain the integrity of data within a contract and avoid performing dangerous operations as a result of untrustworthy inputs. These techniques allow for static analysis that provably eliminates large classes of vulnerabilities, including the bugs that allowed attackers to extract and freeze tens of millions of dollars in the two Parity Wallet incidents, as well as some reentrancy bugs like those that doomed the DAO.

Selfish Mining Re-examined
Support Grand Challenges:
Safety and Compliance

This project revisits the selfish mining (SM) strategy in two ways. First, we present a modified SM strategy, convert selfish mining, that, perplexingly, is more profitable than Nakamoto even when the attacker performs no selfish mining after a difficulty adjustment. This strategy has the added benefit that it is even harder to detect than pure SM, and may additionally increase token value through deflation. Second, we analyze the profitability of SM under several difficulty adjustment schemes.

Autonomous Blockchains
Support Grand Challenges:
Scaling and Performance

Autonomous blockchains are a new blockchain architecture based on free-standing, immutable, eidetic databases that implement independent timelines, linked together through interactions. Autonomous blockchains can be realized inside trusted execution environments, to provide not only blockchain-like integrity and auditability guarantees, but also support the storage and querying of private data. For more info, please see https://credb.systems/

T-Rex
Support Grand Challenges:
Correctness by Design and Construction
Scaling and Performance

This project proposes a real-time and trust-free cryptocurrency exchange based on Intel SGX. It can effectively prevent eclipse attacks without assuming trusted clocks. It also prevents a malicious trader who colludes with the server from reneging on a trade after observing the price fluctuations.

Saber
Support Grand Challenges:
Correctness by Design and Construction
Scaling and Performance

This project proposes the paradigm for parallel and asynchronous smart contract execution. Our paradigm distinguishes between consensus nodes and execution nodes. It allows different groups of execution nodes to execute transactions in parallel, and meanwhile, consensus nodes can continue ordering transactions and processing execution results in a non-blocking way. Due to our new dispute resolution strategy, it (empirically) only requires 10 execution nodes in each group. Moreover, it requires no coordination among execution nodes and can effectively prevent livelocks.

monoCash
Support Grand Challenges:
Correctness by Design and Construction

This project proposes the first off-chain payment network that is channel-free, thereby it is a one-hop, routing-free, concurrency-friendly, rebalancing-free, and fully decentralized.

HiveMind
Support Grand Challenges:
Confidentiality

HiveMind is a blockchain-based machine learning platform allowing participants to contribute data and train models in a fully decentralized way. It leverages federated learning to reduce overhead both in communication and computation. It combines a novel blockchain-based secure aggregation protocol with client-level differential privacy to prevent information leakage from the model parameters.

TxProbe
Support Grand Challenges:
Scaling and Performance

TxProbe is a mechanism for inferring the topology of the Bitcoin P2P network, making use of how nodes process out-of-order (or ("orphan")) transactions. It can be used to take snapshots of the network over a period of minutes. For more info, please see https://arxiv.org/abs/1812.00942

SaUCy
Support Grand Challenges:
Safety and Compliance

Universal Composability (UC) is a unifying framework for cryptography theory. SaUCy is a process calculus and programming language that aims to use UC as the foundation for modular protocol implementations.

Avalanche
Support Grand Challenges:
Scaling and Performance

BFT consensus used by cryptocurrencies consists of two families, traditional consensus and Nakamoto's consensus. The former is usually leader-based, quadratic in message complexity. It requires precise membership knowledge, and suffers from leader bottleneck as it scales up in size. While the latter does not require membership, it is poor in performance and wasteful in energy due to PoW. This project proposes the third, new category of consensus protocols that is PoW-free, leader-less, committee-less, permission-less. It exerts the powerful meta-stability inspired by epidemic protocols, and operators as fast as the network propagates. For more info, please see https://avalanchelabs.org/QmT1ry38PAmnhparPUmsUNHDEGHQusBLD6T5XJh4mUUn3v.pdf

HoneyBadgerMPC
Support Grand Challenges:
Scaling and Performance
Confidentiality
Safety and Compliance

Multi-Party Computation (MPC) is a flexible paradigm for computing on confidential data. HoneyBadgerMPC is an asynchronous MPC protocol and implementation that scales to large networks and provides blockchain-grade fault tolerance and availability guarantees. For more info, please see https://github.com/initc3/HoneyBadgerMPC/

I Can't Believe It's Not Stake
Support Grand Challenges:
Scaling and Performance
Correctness by Design and Construction

Dozens of Proof-of-Stake cryptocurrencies are vulnerable to resource exhaustion attacks due to incomplete validation of blocks prior to allocating storage resources (disk, memory) to data from untrusted peers.

PISA Outsourcing
Support Grand Challenges:
Scaling and Performance
Safety and Compliance

The security guarantees of Payment Channel Networks (PCNs) rely on the availability of an online party to defend honest nodes in cases of a spurious disputes. PISA is a protocol for outsourcing this task to a limited third party while receiving a fair exchange receipt. For more info, please see https://eprint.iacr.org/2018/582.pdf

Sprites and State Channels
Support Grand Challenges:
Safety and Compliance
Scaling and Performance

Off-chain payment channel networks (PCNs) are a leading approach for improving the scalability of blockchains. Sprites is an innovative construction that reduces the worst-case lockup time during which, funds must be held in escrow for a PCN payment. For more info, please see https://arxiv.org/abs/1702.05812

Bone Crusher 2.0
Support Grand Challenges:
Safety and Compliance

The late legal scholar Greg Lastowka wrote about law, property, and self-government in virtual worlds like Ultima Online. His observations are relevant to blockchains and their communities of users.

All Smart Contracts Are Ambiguous
Support Grand Challenges:
Safety and Compliance

Legal contracts are written in natural language, which can introduce ambiguity as to their meaning. Blockchain-based smart contracts are written in programming languages, which seems to give them precise, objective meanings. But because the semantics of a smart contract can change if participants fork the underlying blockchain or revise its protocol, the meaning of a smart contract is always subject to this latent ambiguity.

Disrupting Blockchain Voting
Support Grand Challenges:
Safety and Compliance

Check back later for more info.

CHURP (CHUrn-Robust Proactive secret sharing)
Support Grand Challenges:

CHURP enables secure secret-sharing in dynamic settings where the committee of nodes storing a secret may change over time. Designed for blockchain settings, CHURP has communication complexity much lower than previous schemes; O(n) on-chain and O(n^2) off-chain in the optimistic case of no node failures.

Paralysis Proofs
Support Grand Challenges:

A (3, 3)-multisignature cryptocurrency wallet experiences access-control paralysis upon loss of a single key, but a (2, 3)-multisig allows any two players to collude and steal funds from the third. Paralysis Proofs address this conundrum and others by allowing multisig parameters to be changed *securely* if users become unavailable. For more info, please see https://eprint.iacr.org/2018/096.pdf

Tesseract
Support Grand Challenges:
Confidentiality

We propose Tesseract, a secure real-time cryptocurrency exchange service. Existing centralized exchnge designs are vulnerable to theft of funds, while decentralized exchanges cannot offer real-time crrosschain trades. All currently deployed exchanges are also vulnerable to frontrunning attacks. Tesseract overcomes these flaws and achieves a best-of-bothworlds design by using Intel SGX as a trusted execution environment. For more info, please see https://eprint.iacr.org/2017/1153.pdf

Ekiden
Support Grand Challenges:
Confidentiality

Ekiden is a system that addresses these critical confidentiality and performance gaps in smart contracts by combining blockchains with Trusted Execution Environments (TEEs). Ekiden leverages a novel architecture that separates consensus from execution, enabling efficient TEE-backed confidentiality-preserving smart-contracts and high scalability. Our prototype (with Tendermint as the consensus layer) achieves example performance of 600x more throughput and 400x less latency at 1000x less cost than the Ethereum mainnet. For more information, please see https://arxiv.org/abs/1804.05141

Public Incompressible Encodings (PIEs)
Support Grand Challenges:
Authenticated Data Feeds

We present a provably secure approach to proving file replication (or other erasure coding) in distributed storage networks (DSNs). Storing multiple copies of a file F is essential in DSNs to ensure against file loss in the event of faulty servers or corrupt data. The public nature of DSNs, however, makes this goal challenging. Files must be encoded and decoded using public coins - i.e., without encryption or other secret-key operations - and retention of files by servers in the network must be verifiable. For more info, please see https://eprint.iacr.org/2018/684.pdf

Ostraka
Support Grand Challenges:
Scaling and Performance

Currently, the capacity of a blockchain node can only scale by replacing hardware. For better performance, one must obtain newer hardware. Node capacity effects both initial sync time and block propagation time in the network. We utilize the parallel nature of the UTXO set to build a scalable node architecture.

The Gap Game
Support Grand Challenges:

Incentive analysis in a PoW cryptocurrency, where transaction fees play a dominant role. We analyze suck systems as a game and show ("mining gaps") occur - periods of time where miners are incentivized to be idle instead of actively mining. We also show in such systems, miners are better off forming coalitions, which leads to a centralized system. For more info, please see https://dl.acm.org/citation.cfm?id=3243737

The Hydra Project
Support Grand Challenges:
Correctness by Design and Construction

Hydra is a cutting-edge Ethereum contract development framework for decentralized security and bug bounties rigorous cryptoeconomic security guarantees mitigating programmer and compiler error.

Solidus: Confidential Financial Transaction Settlement on a Distributed Ledgers
Support Grand Challenges:
Scaling and Performance
Confidentiality

Solidus is a cryptocurrency ("blockchain") that can be run by a confederation or consortium of trustworthy entities-- -banks, governments, auditors, etc. While it retains some of the benefits of decentralization, Solidus offers higher performance and tighter governance and control than existing cryptocurrencies such as Bitcoin. Many successful peer-to- peer technologies have historically been eclipsed or supplanted by centralized or commercial systems (e.g., in the online music industry). Solidus addresses the possibility and desire by many financial institutions that cryptocurrencies and contracts will follow a similar path. For more info, please see the Solidus presentation at our 2016 IC3 Retreat (https://tinyurl.com/ic3retreat) in NYC.

Bitcoin-NG: A Next-generation Blockchain Protocol
Support Grand Challenges:
Scaling and Performance

Bitcoin-NG is a new protocol pioneered by IC3. It addresses the scalability bottleneck of Bitcoin by enabling the Bitcoin network to achieve the highest throughput allowed by the network conditions. Paradoxically, not only does it improve transaction throughput, it also reduces transaction latencies -- it is possible to get an initial transaction confirmation in seconds rather than in minutes. And it does so without changing Bitcoin’s open architecture and trust model. Our blockchain test bed Miniature World simulated Bitcoin-NG at 15% the size of the operational Bitcoin system, where we showed that Bitcoin–NG is only limited by the network. For more info, please see our paper (http://arxiv.org/abs/1510.02037).

Miniature World: A Test Bed for Simulating Real World Blockchain
Support Grand Challenges:
Scaling and Performance

Miniature World is a large blockchain emulation test bed at Cornell University consisting of ~1000 nodes. This test bed enables us to run experiments on different blockchains, and a variety of use cases, using realistic internet latencies to evaluate real world scenarios (as referenced above for Bitcoin-NG). We make Miniature World available for our Industry Sponsors to evaluate various block chains and their use cases. For more info about becoming an IC3 Industry Sponsor, please see http://www.initc3.org/partners.html.

Fruitchain: A new Approach for Incentive Compatible Blockchains
Support Grand Challenges:
Scaling and Performance

Most of today's blockchains, such as Bitcoin, are not "incentive compatible", meaning they are quite vulnerable to strategic gaming by dishonest adversaries. For example, IC3 has proven that the Bitcoin blockchain can be compromised by miners or mining pools with much less than 50% of the mining hash power. Fruitchain is an innovative blockchain methodology that discourages dishonest gaming, by making it extremely unprofitable for an adversary with less than 50% of the hash power, achieving an epsilon-equilibrium or near-Nash equilibrium. For more info, please see the Fruitchain presentation by IC3 co-director Professor Elaine Shi at our 2016 IC3 Retreat (https://tinyurl.com/ic3retreat) in NYC.

Falcon Network: A High-Performance, Wide Area Interconnect for Blockchains
Support Grand Challenges:
Scaling and Performance

The Falcon Network achieves gains over current approaches through minimal validation and cut-through routing. No special software is required on clients, and it is fundamentally faster than all other known techniques. For more info, please see http://www.falcon-net.org.

FLAC: A Calculus for Flow-Limited Authorization
Support Grand Challenges:
Correctness by Design and Construction

Real-world applications routinely make authorization decisions based on dynamic computation. Integrity of the system might be compromised if attackers can improperly influence the authorizing computation. Confidentiality can also be compromised by authorization, since authorization decisions are often based on sensitive data such as membership lists and passwords. Flow-Limited Authorization Calculus (FLAC) is both a simple, expressive model for reasoning about dynamic authorization and also a language for securely implementing various authorization mechanisms. FLAC provides strong end-to- end information security guarantees even for programs that incorporate and implement rich dynamic authorization mechanisms. For more info, please see the presentation by Professor Andrew Myers “Verifying Information Security of Code in Dynamic Systems” at our 2016 IC3 Retreat (https://tinyurl.com/ic3retreat) in NYC.

Theoretical Foundations for Secure Decentralized Systems
Support Grand Challenges:
Correctness by Design and Construction

This work explores the theoretical basis for the security and stability of open decentralized systems. The benefits of decentralization include resistance to many kinds of attacks, diversity, and diffusion of power. The novelty and inspiring success of Bitcoin has provided new evidence that secure decentralized systems are more feasible than once thought. On the other hand, even Bitcoin risks becoming centralized if thrown off-balance, e.g. due to mining pools, ASIC farms, or political schisms. Furthermore, IC3 and collaborators just released a research paper that analyzed The Digital Autonomous Organization (DAO) and its voting mechanism. This paper identifies problems with The DAO's mechanism design that incentivize investors to behave strategically; that is, at odds with truthful voting on their preferences. We then outline potential attacks against The DAO made possible by these behaviors. For more info, please see http://hackingdistributed.com/2016/05/27/dao-call-for-moratorium.

Hawk: Privacy-Preserving Blockchain & Smart Contracts
Support Grand Challenges:
Correctness by Design and Construction
Confidentiality

Existing blockchain-based cryptocurrencies such as Bitcoin and Ethereum store all financial transactions in the clear on the blockchain. This compromises the privacy of financial transactions, which is essential in numerous applications. Hawk is a blockchain-based smart contract system that stores encrypted transactions on the blockchain, and relies on cryptography to retain the security of the cryptocurrency. For more info, please see http://oblivm.com/hawk.

Town Crier: Authenticated Data Feeds for Smart Contracts
Support Grand Challenges:
Confidentiality
Authenticated Data Feeds
Sound Migration

In order to reason about the real world, smart contracts in cryptocurrency systems will rely on informational input from what we call authenticated data feeds (ADFs); such information can include stock prices, meteorological reports, news, and other current events. It is therefore important that an ADF be trustworthy, in the sense of providing security against manipulation by an attacker attempting to influence the outcome of a contract. By utilizing trusted hardware to provide reliable, digitally signed attestations on data to client contracts, the Town Crier system can serve as a trustworthy ADF under minimal trust assumptions about its operator. For further details, please see our paper (http://www.initc3.org/files/tc.pdf).

Virtual Notary: A Free and Secure Electronic Attestation Service
Support Grand Challenges:
Authenticated Data Feeds

Virtual Notary is a service for attesting to online factoids. Virtual Notary issues both freestanding certificates as well as immutable records on the Bitcoin blockchain. It has been operational for more than 3 years, and certified more than 600,000 factoids. For more info, please see http://virtual-notary.org.

EtherScrape: A Complementary Block Explorer for the Ethereum Blockchain
Support Grand Challenges:
Authenticated Data Feeds

Smart Contracts in Ethereum are written in a high-level programming language (typically Serpent or Solidity) and then compiled down to bytecode for the Ethereum virtual machine. This compilation step removes a lot of the useful information found in the high level source code, such as comments, names of variables, etc. If you can identify the high-level source code for a contract, you have a better chance of figuring out what it does. EtherScrape uses fingerprinting to match each smart contract on the blockchain (that is, the compiled bytecode) to the high-level source code that created it. For more info, please see http://etherscrape.com.

Gyges: Crime in Decentralized Smart Contracts
Support Grand Challenges:
Safety and Compliance

Two of the most widely desired goals for "Bitcoin 2.0" are privacy and more expressive smart contracts. Many uses of cryptocurrency have a clear and legitimate need for privacy (e.g., financial service companies are expected to protect the privacy of their clients' transactions). General purpose smart contract programming frameworks make it easy to tinker, prototype, and search for the next "killer application" for cryptocurrencies. These two directions seem to be at odds with each other; however, through the use of sophisticated cryptography (like zero knowledge proofs and multi-party computation), we explore how to achieve both goals at once. For further details, please see our paper at http://www.initc3.org/files/Gyges.pdf.