EIP-6988: Elected block proposer has not been slashed


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      Standards Track: Core
    
  
  
    
      EIP-6988: Elected block proposer has not been slashed
    
    
      
        
      
    
    
      
        
      
    
  

  Prevents a slashed validator from being elected as a block proposer

  	Authors	Mikhail Kalinin (@mkalinin)
	Created	2023-05-04
	Discussion Link	https://ethereum-magicians.org/t/eip-6988-elected-block-proposer-has-not-been-slashed/14349


  


  

  
    Table of Contents

    	Abstract
	Motivation
	Specification
	Rationale
    	Modifying get_beacon_proposer_index


  
	Backwards Compatibility
	Test Cases
	Reference Implementation
	Security Considerations
	Copyright



  


  
      
      
         Abstract
      
      
    


Introduces a modification to the consensus layer specification which ensures that slashed validator cannot be elected as block proposer.

  
    
      
      
         Motivation
      
      
    


A block proposed by a slashed validator is rejected by the corresponding validity check in the phase0/process_block_header function as defined in the consensus layer specification.


At the same time the definition of the phase0/compute_proposer_index allows for a slashed validator to be elected as a proposer. This contradiction effectively leads to a missed proposal if it is supposed to be made by a slashed validator.


The impact of the proposed fix in the case of a single slashing on Ethereum Mainnet is negligible but it becomes significant in the case of correlated slashings. For instance, a correlated slashing of 1/10th of a validator set can lead to 1/10th of missed proposals in a number of epochs after the slashing.

  
    
      
      
         Specification
      
      
    


Specification of the proposed change can be found in /_features/eip6988/beacon-chain.md.

  
    
      
      
         Rationale
      
      
    

  
    
      
      
         Modifying get_beacon_proposer_index
      
      
    


This function is modified to read a proposer index from a beacon state if a slot of a latest block header is the same as the state.slot.


This modification is done to make the function return correct proposer index in the case when the proposer of a given block is being slashed during processing of the block.

  
    
      
      
         Backwards Compatibility
      
      
    


This fix changes proposer election mechanism in a backwards incompatible way and requires a hard fork to be deployed.

  
    
      
      
         Test Cases
      
      
    


The following test cases were added to cover this change:


	test_slashed_proposer_rewarded_for_sync_aggregate_inclusion
	test_slashed_proposer_rewarded_for_attestation_inclusion
	test_slashed_validator_not_elected_for_proposal
	test_slashed_validator_elected_for_proposal


  
    
      
      
         Reference Implementation
      
      
    


Reference implementation is in the same place as Specification.

  
    
      
      
         Security Considerations
      
      
    


There are no observed security issues introduced by the proposed change.

  
    
      
      
         Copyright
      
      
    


Copyright and related rights waived via CC0.


  Citation

  Please cite this document as:

  
  Mikhail Kalinin (@mkalinin), "EIP-6988: Elected block proposer has not been slashed [DRAFT]," Ethereum Improvement Proposals, no. 6988, May 2023. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-6988.






      
    
  

  

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