Alexander Chepurnoy

The Web of Mind

Towards a New Frontier of the Smart Contracts: Hawk and Enigma

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Introduction

After the AT Project(incorporated into Burst and Qora) and then Ethereum launch we got the ability to store programmable logic of potentially arbitrary complexity on the blockchain and then execute it on an each node. The “world computer” approach has some very obvious problems though:

  • scalability - executing a code on an each node in a network is just impractical. With tens (or hundreds) of companies planning to build something atop of the Ethereum, the reality is all those projects can’t fit into a single blockchain probably

  • privacy - in many real-world scenarios contractors are not willing to disclose some of data or code details to the public. Current smart contracts solutions are not preserving privacy in any way

Research units around the world are trying to solve the issues. In this review first two well-known approaches, namely Hawk and Enigma will be covered.

Language-Based Approach

Both projects offer the same approach to develop contracts, a language to be compiled into a privacy-preserving onchain + offchain cryptographic protocol.

Scalability

In both projects a contract is executed as on-chain + off-chain protocol so only reasonable minimum of data is going into a blockchain. Probably time will define a special kind transactional design for a blockchain better suited for storing a lot of certain factual information. At the moment both papers don’t imply blockchain implementation details.

Privacy

Approach to preserve privacy is different. Enigma uses [secure multi-party computations] (https://en.wikipedia.org/wiki/Secure_multi-party_computation)(SMC) based on Shamir’s secret sharing with MACs and commitments stored on the blockchain. A Hawk contract requires minimally trusted manager which cannot change outcome of a contract and also cannot aborts a protocol without losing its security deposit(but it can disclose private information involved).

Enigma vs. Hawk

Pretty short and concise Enigma whitepaper describes a platform concept consisting of blockchain, DHT(acting as general-purpose database) & SMC. Some practical aspects of the system e.g. fees & deposits are not well described yet though.

In contrast, much bigger Hawk paper isn’t about platform description mostly, but about a solid and proven approach to construct a compiler translating high-level programs written within ideal world model into real-world cryptographic protocol. I hope a whitepaper with a platform description will be released as well. From the paper, they have working compiler already at least.

Conclusion

It seems Enigma team is going to release more or less concrete smart contracts platform aiming to solve the most painful problems of nowaday solutions, namely scalability and privacy. Hawk team is going to open-source the framework, though it’s not clear at the moment what will be there except of a compiler.

Both projects are very exciting and will move us to a next frontier in building a decentralized economies. So have luck both of the teams!

White Papers:

  1. Hawk: The Blockchain Model of Cryptography and Privacy-Preserving Smart Contracts. Available online at https://eprint.iacr.org/2015/675.pdf.

  2. Enigma: Decentralized Computation Platform with Guaranteed Privacy. Available online at http://enigma.media.mit.edu/enigma_full.pdf.

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