Streamlining validation logic across proposal lifecycle

[grarco]

Reported by Informal Systems.

Description

Several validations are redundantly executed across mempool validations, prepare proposal, process proposal, and finalize block. This redundancy is unnecessary because an invalid transaction will not be inserted into the mempool, and therefore, it will not be considered in the prepare proposal. Similarly, the relationship between process proposal and finalize block involves redundant validations.

#Problem Scenarios

Some of redundant validations:
• Redundant signature check in mempool validation (code) and prepare proposal (code),
• Redundant signature check in process proposal (code) and finalize block (code).
• Duplication of check_tx_allowed in mempool validation (code), process proposal (code), and finalize block (code).

Recommendation

Consolidate validation checks to occur only at the earliest appropriate stage (e.g., mempool validation and process proposal).