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Adelie: Detection and prevention of Byzantine behaviour in DAG-based consensus protocols

Andrey Chursin

TL;DR

The paper tackles the vulnerability of uncertified DAGs in DAG-based BFT consensus by introducing Adelie, a protocol that adds the block_view and critical_block rules to Mysticeti’s uncertified DAG framework. It leverages Shoal++-style leadership and a production-ready implementation (bftd) to achieve low latency around 0.5 RTT per element and high throughput, while actively detecting and curbing Byzantine equivocation. Key contributions include formalized validity and liveness mechanisms (block_view, critical_block, unlock), a practical architecture with efficient state management and networking, and an empirical evaluation showing up to 450K TPS with 630 ms finality under realistic deployment. The work demonstrates that high-performance DAG-based BFT is feasible in practice, offering significant potential for scalable, robust distributed ledgers.

Abstract

Recent developments in the Byzantine Fault Tolerant consensus protocols have shown the DAG-based protocols to be a very promising technique. While early implementations of DAG-based protocols such as Narwhal/Bullshark trade high throughput for a low latency, the latest versions of DAG-based protocols such as Mysticeti and Shoal++ show that indeed a latency comparable to that of traditional consensus protocols such as HotStuff can be achieve with the DAG-based consensus protocols while still maintaining high throughput. Mysticeti in particular achieves a low latency by implementing a novel approach of using an uncertified DAG - a significant breakthrough comparing to the certified DAG used in the previous generations of the protocol. However, the uncertified DAG exposes the system to new vectors of attacks by Byzantine validators that did not exist in the certified DAG protocols. In this paper we describe those issues and present the Adelie protocol, that addresses issues that comes with an uncertified DAG. We also incorporate some of the techniques from the Shoal++ to reduce latency even further. This paper also presents an implementation of Adelie protocol - bftd that demonstrates yet another breakthrough in the maximum achieved TPS and low latency.

Adelie: Detection and prevention of Byzantine behaviour in DAG-based consensus protocols

TL;DR

The paper tackles the vulnerability of uncertified DAGs in DAG-based BFT consensus by introducing Adelie, a protocol that adds the block_view and critical_block rules to Mysticeti’s uncertified DAG framework. It leverages Shoal++-style leadership and a production-ready implementation (bftd) to achieve low latency around 0.5 RTT per element and high throughput, while actively detecting and curbing Byzantine equivocation. Key contributions include formalized validity and liveness mechanisms (block_view, critical_block, unlock), a practical architecture with efficient state management and networking, and an empirical evaluation showing up to 450K TPS with 630 ms finality under realistic deployment. The work demonstrates that high-performance DAG-based BFT is feasible in practice, offering significant potential for scalable, robust distributed ledgers.

Abstract

Recent developments in the Byzantine Fault Tolerant consensus protocols have shown the DAG-based protocols to be a very promising technique. While early implementations of DAG-based protocols such as Narwhal/Bullshark trade high throughput for a low latency, the latest versions of DAG-based protocols such as Mysticeti and Shoal++ show that indeed a latency comparable to that of traditional consensus protocols such as HotStuff can be achieve with the DAG-based consensus protocols while still maintaining high throughput. Mysticeti in particular achieves a low latency by implementing a novel approach of using an uncertified DAG - a significant breakthrough comparing to the certified DAG used in the previous generations of the protocol. However, the uncertified DAG exposes the system to new vectors of attacks by Byzantine validators that did not exist in the certified DAG protocols. In this paper we describe those issues and present the Adelie protocol, that addresses issues that comes with an uncertified DAG. We also incorporate some of the techniques from the Shoal++ to reduce latency even further. This paper also presents an implementation of Adelie protocol - bftd that demonstrates yet another breakthrough in the maximum achieved TPS and low latency.
Paper Structure (15 sections, 6 figures)

This paper contains 15 sections, 6 figures.

Table of Contents

  1. Introduction
  2. Uncertified DAG
  3. Flooding the DAG
  4. Phantom DAG
  5. Adelie protocol
  6. General assumptions
  7. Block structure
  8. Block validity rules
  9. Block view rule
  10. Critical block rule
  11. Unlock critical block support
  12. Implementation
  13. Architecture
  14. Evaluation
  15. Conclusion

Figures (6)

  • Figure 1: Block view detecting validator producing two different blocks at the same round
  • Figure 2: Block view detecting validator producing non-linear sequence of own blocks
  • Figure 3: Each red block is a critical block for a corresponding blue block
  • Figure 4: Latency with 100% validators up
  • Figure 5: Latency with 25% validators malfunctioning
  • ...and 1 more figures