Dusk Network Development Update — February 2020

Mar 06, 2020

By: Toghrul Maharramov

A monthly development update series created to embrace the transparency and inclusivity that we strive for at Dusk Network

Development

The team has finalized the specification of Confidential Security Contract Standard 2.0 (XSC 2.0). This overhaul of the original XSC standard is a result the consultation and feedback from our partners. XSC 2.0 drastically expands on the functionality of the original, providing issuers with a much more customizable framework. The improved standard ships with a more granular control of contract governance, inter-contract interaction functionality (including whitelisting contracts), a revised dividend payout methodology and more.

Dusk Network Enhancement Recommendation (DER) is a documentation standard for protocol enhancement proposals, that we are planning to make public soon. Our DER standard is inspired by Bitcoin’s BIP and Ethereum’s EIP. The publication will coincide with the release of a set of preliminary DERs already implemented and DERs recommended to be made standard. Most notable are DER-2 (Confidential Token Standard) and DER-7 (Confidential Security Contract [XSC 2.0] Standard).

We have made intense software improvements on the world’s first Rust-based PLONK implementation. The codebase has been migrated to use BLS12-381 elliptic curve. BLS12-381 is a pairing-friendly elliptic curve which has a ≈2^128 industry-standard security level, in-line with other cryptographic primitives utilized by the Dusk Network protocol. The team has also continued working on a domain-specific language (DSL) for circuit building, which should simplify the technical overhead of designing custom circuits. An arithmetic circuit is a model for computing polynomials (a mathematical expression consisting of variables and coefficients). Arithmetic circuits are utilized in zero-knowledge proofs to convince the verifier that the prover is capable of satisfying the circuit (i.e. knows the correct solution to the polynomial in question).

Research

In light of the recent publication on utilization of cryptographic constructions to improve timestamping capabilities of Proof-of-Stake (PoS) protocols, and by conducting our own internal theoretical experimentations, the team is further researching new techniques to improve on the current prevention methods for “long-range” attacks.

In a “long-range attack”, an adversary obtains the secret keys associated with the expired stakes (for example through bribing) and attempts to rewrite the chain history from that particular point in time, in a so-called “costless simulation attack”. The main goal of the adversary is to create a new chain history, and have this chain accepted as the main branch. As opposed to Proof-of-Work (PoW) protocols, and as the name of the attack implies, this block generation process bears negligible cost for the attacker in Proof-of-Stake protocols.

Currently, the go-to method to combat the long-range attack vector is to introduce sporadic checkpointing. This way, the blockchain’s history up until the latest checkpoint cannot be rewritten by an attacker. One condition for the aforementioned method is that it requires additional trust assumptions to be imposed on nodes joining the network (i.e. bootstrapping). More specifically, this assumption asserts that at any given point in time, up until the latest checkpoint, 51% of the node peers (i.e. connections) are to be honest.

Instead, the aforementioned paper above proposes the use of Verifiable Delay Functions (VDFs) to prevent long-range attacks. Verifiable Delay Functions represent a family of mathematical algorithms, which are computed in a predefined number of sequential steps, meaning that the computation of the solution cannot be parallelized. Unlike hash functions, utilized in the majority of Proof-of-Work protocols including Bitcoin’s Nakamoto consensus, there is constant bound imposed on the advantage that the attacker can have in terms of the time taken to compute the solution. Meaning that in classic Proof-of-Work protocols, the attacker can effectively halve the time required to compute a given solution by doubling his computational power, however, with the use of VDFs, the attacker advantage is limited by a certain constant, no matter the amount of computational power at his disposal.

The use of VDFs in Proof-of-Stake protocols, including Segregated Byzantine Agreement utilized by Dusk Network, means that in order to commit a successful long-range attack, an attacker is required to spend time proportional to the time difference between the point in the chain where the attack was commenced and the latest available block computing the VDF solutions. For example, if an attacker wants to rewrite the chain history for the previous year and the constant bound is set at 2, then the time taken for the attacker to compute the VDF solutions for the previous year-worth of chain history would be at least 6 months, meaning that by the time the computation has been finished, the original chain would have progressed another 6 months further. The utilization of a VDF construct implies that the checkpointing and the 51% peer honesty assumptions no longer need to hold for nodes joining the network and to successfully rebuild the correct chain.

Community

On february 27th, we co-hosted the Blockchain beyond the hype event at LTO Network office in Amsterdam. At the event we shared the exciting news of tokenizing thousands of Dutch corporations with Netherland’s leading incorporation platform Firm24. This news has been revealed in an exclusive story by CoinDesk.

Earlier this month, Jelle Pol presented and led the 2Tokens session at CMS head office Amsterdam on Building Token Finance, further expanding our collaboration with the key players in the DeFi scene.

Dusk Network expands its marketing team in response to brand growth. The team has recruited a PR-executive and a Marketing Strategist to help lead its online and offline marketing activities, as the company seeks to connect the global financial sector. Mels Dees, Co-Founder and Marketing Lead at Dusk Network added: “I am happy to welcome Robin and Sabine to the team. Their experience and skills have already proven itself on multiple occasions when we needed to explain the complexities of Dusk Network to a diverse audience.


About Dusk Network

Dusk Network is an open-source and privacy-oriented blockchain based on years of academic research. You can use Dusk Network to create smart contracts that control digital assets and securities.

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