EIP-4345: Difficulty Bomb Delay to June 2022


  Ethereum Improvement Proposals
        
        
          
            
              
            
          
        

        AllCoreNetworkingInterfaceERCMetaInformational

      



      
        
  
    

  
    
    
    
    
    
      Standards Track: Core
    
  
  
    
      EIP-4345: Difficulty Bomb Delay to June 2022
    
    
      
        
      
    
    
      
        
      
    
  

  Delays the difficulty bomb to be noticeable in June 2022.

  	Authors	Tim Beiko (@timbeiko), James Hancock (@MadeOfTin), Thomas Jay Rush (@tjayrush)
	Created	2021-10-05


  


  

  
    Table of Contents

    	Abstract
	Motivation
	Specification
	Rationale
	Backwards Compatibility
	Security Considerations
	Copyright



  


  
      
      
         Abstract
      
      
    

Starting with FORK_BLOCK_NUMBER the client will calculate the difficulty based on a fake block number suggesting to the client that the difficulty bomb is adjusting 10,700,000 blocks later than the actual block number.

  
    
      
      
         Motivation
      
      
    

Targeting for The Merge to occur before June 2022. If it is not ready by then, the bomb can be delayed further.

  
    
      
      
         Specification
      
      
    

  
    
      
      
         Relax Difficulty with Fake Block Number
      
      
    

For the purposes of calc_difficulty, simply replace the use of block.number, as used in the exponential ice age component, with the formula:

    fake_block_number = max(0, block.number - 10_700_000) if block.number >= FORK_BLOCK_NUMBER else block.number




  
    
      
      
         Rationale
      
      
    


The following script predicts a ~0.1 second delay to block time by June 2022 and a ~0.5 second delay by July 2022. This gives reason to address because the effect will be seen, but not so much urgency we don’t have space to work around if needed.


def predict_diff_bomb_effect(current_blknum, current_difficulty, block_adjustment, months):
    '''
    Predicts the effect on block time (as a ratio) in a specified amount of months in the future.
    Vars used for predictions:
    current_blknum = 13423376 # Oct 15, 2021
    current_difficulty = 9545154427582720
    block adjustment = 10700000
    months = 7.5 # June 2022
    months = 8.5 # July 2022
    '''
    blocks_per_month = (86400 * 30) // 13.3
    future_blknum = current_blknum + blocks_per_month * months
    diff_adjustment = 2 ** ((future_blknum - block_adjustment) // 100000 - 2)
    diff_adjust_coeff = diff_adjustment / current_difficulty * 2048
    return diff_adjust_coeff


diff_adjust_coeff = predict_diff_bomb_effect(13423376,9545154427582720,10700000,7.5)
diff_adjust_coeff = predict_diff_bomb_effect(13423376,9545154427582720,10700000,8.5)




  
    
      
      
         Backwards Compatibility
      
      
    

No known backward compatibility issues.

  
    
      
      
         Security Considerations
      
      
    

Misjudging the effects of the difficulty can mean longer blocktimes than anticipated until a hardfork is released. Wild shifts in difficulty can affect this number severely. Also, gradual changes in blocktimes due to longer-term adjustments in difficulty can affect the timing of difficulty bomb epochs. This affects the usability of the network but unlikely to have security ramifications.


In this specific instance, it is possible that the network hashrate drops considerably before The Merge, which could accelerate the timeline by which the bomb is felt in block times. The offset value chosen aimed to take this into account.

  
    
      
      
         Copyright
      
      
    

Copyright and related rights waived via CC0.


  Citation

  Please cite this document as:

  
  Tim Beiko (@timbeiko), James Hancock (@MadeOfTin), Thomas Jay Rush (@tjayrush), "EIP-4345: Difficulty Bomb Delay to June 2022," Ethereum Improvement Proposals, no. 4345, October 2021. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-4345.






      
    
  

  

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