EIP-155: Simple replay attack protection


  Ethereum Improvement Proposals
        
        
          
            
              
            
          
        

        AllCoreNetworkingInterfaceERCMetaInformational

      



      
        
  
    

  
    
    
    
    
    
      Standards Track: Core
    
  
  
    
      EIP-155: Simple replay attack protection
    
    
      
        
      
    
    
      
        
      
    
  

  

  	Authors	Vitalik Buterin (@vbuterin)
	Created	2016-10-14


  


  

  
    Table of Contents

    	Hard fork
	Parameters
	Specification
	Example
	Rationale
	List of Chain ID’s:



  


  
      
      
         Hard fork
      
      
    

Spurious Dragon

  
    
      
      
         Parameters
      
      
    

	FORK_BLKNUM: 2,675,000
	CHAIN_ID: 1 (main net)


  
    
      
      
         Specification
      
      
    


If block.number >= FORK_BLKNUM and CHAIN_ID is available, then when computing the hash of a transaction for the purposes of signing, instead of hashing only six rlp encoded elements (nonce, gasprice, startgas, to, value, data), you SHOULD hash nine rlp encoded elements (nonce, gasprice, startgas, to, value, data, chainid, 0, 0).  If you do, then the v of the signature MUST be set to {0,1} + CHAIN_ID * 2 + 35 where {0,1} is the parity of the y value of the curve point for which r is the x-value in the secp256k1 signing process.  If you choose to only hash 6 values, then v continues to be set to {0,1} + 27 as previously.


If block.number >= FORK_BLKNUM and v = CHAIN_ID * 2 + 35 or v = CHAIN_ID * 2 + 36, then when computing the hash of a transaction for purposes of recovering, instead of hashing six rlp encoded elements (nonce, gasprice, startgas, to, value, data), hash nine rlp encoded elements (nonce, gasprice, startgas, to, value, data, chainid, 0, 0). The currently existing signature scheme using v = 27 and v = 28 remains valid and continues to operate under the same rules as it did previously.

  
    
      
      
         Example
      
      
    


Consider a transaction with nonce = 9, gasprice = 20 * 10**9, startgas = 21000, to = 0x3535353535353535353535353535353535353535, value = 10**18, data='' (empty).


The “signing data” becomes:


0xec098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a764000080018080





The “signing hash” becomes:


0xdaf5a779ae972f972197303d7b574746c7ef83eadac0f2791ad23db92e4c8e53





If the transaction is signed with the private key 0x4646464646464646464646464646464646464646464646464646464646464646, then the v,r,s values become:


(37, 18515461264373351373200002665853028612451056578545711640558177340181847433846, 46948507304638947509940763649030358759909902576025900602547168820602576006531)





Notice the use of 37 instead of 27. The signed tx would become:


0xf86c098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a76400008025a028ef61340bd939bc2195fe537567866003e1a15d3c71ff63e1590620aa636276a067cbe9d8997f761aecb703304b3800ccf555c9f3dc64214b297fb1966a3b6d83




  
    
      
      
         Rationale
      
      
    


This would provide a way to send transactions that work on Ethereum without working on ETC or the Morden testnet. ETC is encouraged to adopt this EIP but replacing CHAIN_ID with a different value, and all future testnets, consortium chains and alt-etherea are encouraged to adopt this EIP replacing CHAIN_ID with a unique value.

  
    
      
      
         List of Chain ID’s:
      
      
    


	CHAIN_ID	Chain(s)
	1	Ethereum mainnet
	2	Morden (disused), Expanse mainnet
	3	Ropsten
	4	Rinkeby
	5	Goerli
	42	Kovan
	1337	Geth private chains (default)



Find more chain ID’s on chainid.network and contribute to ethereum-lists/chains.


  Citation

  Please cite this document as:

  
  Vitalik Buterin (@vbuterin), "EIP-155: Simple replay attack protection," Ethereum Improvement Proposals, no. 155, October 2016. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-155.






      
    
  

  

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        Ethereum Improvement Proposals (EIPs) describe standards for the Ethereum platform, including core protocol specifications, client APIs, and contract standards.