EIPs/EIPS/eip-155.md

eip	title	author	type	category	status	created
155	Simple replay attack protection	Vitalik Buterin (@vbuterin)	Standards Track	Core	Final	2016-10-14

Hard fork

Spurious Dragon

Parameters

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

Specification

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 signing or recovering, instead of hashing only the first six elements (i.e. nonce, gasprice, startgas, to, value, data), hash nine elements, with v replaced by CHAIN_ID, r = 0 and s = 0. The currently existing signature scheme using v = 27 and v = 28 remains valid and continues to operate under the same rules as it does now.

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.