🔰 Final Standard

PIP-26: Minimum Availability Score

Authors	B00f (@b00f)
Discussion	View Discussion PIP-26
Category	Core
Created	09-06-2024

Abstract
Motivation
Specification
Backward Compatibility
Security Considerations
References

Abstract #

This proposal suggests setting the Minimum Availability Score to 0.666667 for validators in the Pactus network. This score ensures that validators who fail to meet this threshold cannot propose a block, thereby maintaining the network’s stability and reliability.

Motivation #

Based on PIP-19 ¹, validators with an Availability Score below the Minimum Availability Score cannot propose blocks. Therefore, it is essential to set a fair and effective minimum threshold to ensure network performance and security.

Specification #

The Availability Score ($S_i$) is calculated by dividing the number of blocks that a validator has signed ($V_i$) by the number of times a validator could sign a block ($N_i$):

\[S_i = \frac{V_i}{N_i}\]

When a block is created, non-faulty validators should include all the signatures they receive in the block certificate. However, faulty validators may fail to do so, either intentionally or unintentionally.

Let’s assume a worst-case scenario where up to 1/3 of validators may be faulty (e.g., due to poor internet connections, unsynchronized clock, selfish behavior, etc.). As a result, a validator’s signature might only be included in 2/3 of the blocks they are supposed to sign:

\[V_i = \frac{2}{3} \times N_i\]

Therefore, the Minimum Availability Score $S_{min}$ is calculated as:

\[S_{min} = \frac{\frac{2}{3} \times N_i}{N_i} = \frac{2}{3} \approx 0.666667\]

Backward Compatibility #

Once the majority of nodes adopt this number, validators with lower scores will no longer receive rewards.

Security Considerations #

This proposal should improve the security of the protocol, as validators will tend to monitor their nodes to avoid falling below the minimum threshold.

References #

PIP-19 - Availability Score for Validators ↩