Simplify EIP-161
EIP-4747 aims to simplify EIP-161 by removing the requirement for implementors to support edge cases that are impossible on Ethereum Mainnet. EIP-161 is considered overly complex and has poorly documented and tested edge cases. EIP-4747 takes advantage of the complete removal of all remaining empty accounts in block 14049881 to clarify EIP-161 and allows implementors to not implement various edge cases that never occurred and are not possible in the future. This EIP permits implementors who do not wish to support historical blocks to not implement state clearing at all. The retroactive replacement of EIP-161 starts from its introduction in block 2675000 and includes setting the nonce of a newly created account to 1 prior to executing initcode. The key words used in this document are to be interpreted as described in RFC 2119.
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Original
Abstract
Simplify the definition of EIP-161, removing the requirement for implementors to support edge cases that are impossible on Ethereum Mainnet.
Motivation
EIP-161 is overly complex and has a number of edge cases that are poorly documented and tested. This EIP takes advantage of the complete removal of all remaining empty accounts in block 14049881 (tx 0xf955834bfa097458a9cf6b719705a443d32e7f43f20b9b0294098c205b4bcc3d
) to clarify it, and allows implementors to not implement various edge cases that never occurred and are not possible in the future.
In particular, this EIP permits implementors who do not wish to support historical blocks to not implement state clearing at all.
Specification
The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC 2119.
Retroactively replace EIP-161, starting from its introduction in block 2675000, with the following rules:
a. When creating an account, set it's nonce to 1
prior to executing initcode.
b. When performing EVM execution treat all empty accounts as if they do not exist. Any operation that would create an empty account instead leaves it non-existent.
c. If one of the following events happens to an empty account X
, it is deleted:
X
receives a zero valueCALL
.X
is the recipient of a zero value transaction.X
is the beneficiary of aSELFDESTRUCT
with zero value.
If the transaction, CALL
or SELFDESTRUCT
is reverted, then the state clearing is also reverted. As a special case on Ethereum Mainnet, in block 2675119 (tx 0xcf416c536ec1a19ed1fb89e4ec7ffb3cf73aa413b3aa9b77d60e4fd81a4296ba
), an empty call is made to an empty account at RIPEMD160
(precompile 0x3
), the call fails out of gas, but the empty account is removed anyway.
The deletion MAY happen immediately or be processed at the end of the transaction. A client may assume that STATICCALL
s to empty accounts never occur and that CALL
s to empty accounts in STATICCALL
contexts never occur.
On Ethereum Mainnet, the only state clearing events after the start of Byzantium are the two listed below. Clients MAY implement post Byzantium state clearing by hardcoding those events.
-
In block 4457731 (tx
0x63791f962e13e6b01ec13d38a8ab66c87c2f5a1768276f866300d900cca808fe
),0xd29DFe5aE95B5C067a91F472Dac0d9be6700A4A9
receives a zero valueSELFDESTRUCT
and is cleared. -
In block 14049881 (tx
0xf955834bfa097458a9cf6b719705a443d32e7f43f20b9b0294098c205b4bcc3d
), the following accounts receive zero value calls and are cleared.Accounts cleared
0x01a3dd7d158e3b4c9d8d2af0ddcf3df0f5e14463 0x0366c731dd7c095dc08896806765a649c6c0885a 0x056c68da52395f1d42c5ba15c4fb956146a4f2c1 0x070ba92497cd4b88a8a9a60795ca7d7f7de0faa3 0x07a1648ce2bed6721a5d25de3c228a296d03fd52 0x07b14ba68f474529cc0bd6a9bffee2bc4090d185 0x07ea32232e37d44134a3071319d228bdab249a60 0x096b7382500fa11c22c54c0422c5e38899a2e933 0x09f3200441bd60522bcf28f3666f8e8dbd19fb62 0x0ad0f3c60696adece09367a9a11c968fb88560bb 0x0af6181e1db22071f38fc162e1610e29d288de04 0x0cdc7fef8f8d0ee77360060930aada1263b26ff7 0x0dac3d571eb5b884a2550db2791d5ac1efca306b 0x0ec857faba49392080b68dd5074d85f34724d04a 0x0f5054f9c674b37d15915ca8925f231edb3afa8c 0x0f78d535e1faad9a982dca2a76d16da4649f7021 0x104c5b235166f26df54f52666d5e77d9e03e353e 0x106b47175965b6d607008544267c91490672a54f 0x1223d5c03b4d52ebed43f781251098c9138c3dd7 0x1251d13cde439378349f039379e83c2641b6269f 0x12c814cebee6bb08a5d1b9d009332bf8b536d645 0x150c63df3da35e590a6d2f7accf2e6f241ea5f1a 0x15ddf20e4eb8b53b823bc45c9bad2670aad907dd 0x1712b1c428f89bc695b1871abfff6b5097350150 0x178df2e27b781f024e90ab0abe9cff7e2f66a5fc 0x1c2bd83dc29095173c4bcc14927811f5141c1373 0x1d12f2fad3603ea871fcb13ac3e30674f9ad903f 0x1f7391b6881b6f025aef25cff737ff3fcb9d7660 0x219a3d724f596a4b75656e9b1569289c71782804 0x21a7fd9228c46ec72f926978f791fc8bfcd277fa 0x23acb760cebd01fe7c92361274a4077d37b59f4c 0x23b249eeeeedd86bc40349f8bb8e2df34bd28f78 0x28d006b1a2309e957005ee575f422af8034f93df 0x28ef72d5614b2833d645aecf8ef7add075eb21e2 0x292966802ffedb6f34f2c8c59df35c9d8f612c24 0x2c2661ddd320017138075aba06999440a902695f 0x2c632be2dc2f47affd07bfce91bd4a27c02f4563 0x2f86de22ced85a7dd0d680fc4266929a72775e27 0x2fa04f15123025ab487dce71668f5265649d0598 0x30f78fd12c17855453e0db166fecf684bb239b8c 0x31534e95353323209cd18ad35c22c2528db6d164 0x336e0e1a14e0136c02bf8dcf0a9a3fe408548262 0x340399588bba5b843883d1ad7afd771a3651447a 0x341d2b82d0924ef42d75ce053654295d34839459 0x34c2b8975b47e13818f496cf80b40566798cf968 0x370e67f45db9c18d6551000e6c0918bc8d346ebf 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0x5e9a0a1bdfdd868706f4554aae21bb2c46da32c2 0x5f3f0d3215db85faa693d99acfb03cca66556671 0x5f6aa25f22edb2347b464312e2508cbc4c6e0162 0x6006f79e4104850ab7c9b0f75918c1e2cf6311df 0x60f5da58bccb716f58b5759a06fc2167fe237c26 0x62d3a444d0af59f9de79f8abeb5c942fcfbfbef5 0x630ea66c8c5dc205d45a978573fa86df5af1fe7a 0x6464f0f96a29934087a955c67a6b53d5ed852e49 0x6653cedb0b7f51c4b0c44079eb45c514df24ecfd 0x66d69ac12b573299f36b108792be75a1e2ccdfdc 0x690ed837d25b46dbf46727fcda7392d997c2bc97 0x696eecbc97189c5b2a8245a8e32517db9960c171 0x69aaff0b7babe85e0a95adfc540e689399db7f24 0x6b71d2ceab5678b607aa1e69b6781f5c7abc9aaf 0x6e03d9cce9d60f3e9f2597e13cd4c54c55330cfd 0x6e278cfecfe96fa5e6d5411ba6eeb765dff4f118 0x6e557f01c9dcb573b03909c9a5b3528aec263472 0x6ec268f8bef9c685d7e04d5cdb61fbb544869a9f 0x6f2ba051b3ce06a90705c22e0241c2b7e32c1af0 0x7063732ced55cfa08aea520f3fe200c39b3df0f5 0x7073a17a0172dfb1e46a62f054d11a775aeac32e 0x71d3718cfa0f9ee8173688fe52bb499e1f36534b 0x74e20aec156674945894d404f8dea602570e62f5 0x783e45c2989e675ffc9d067914d7de3ff68aee58 0x7a5f843f884bb15d070806e1ff59b6c6f74bbe2d 0x7c6b1706c86ea76a0e232324f249e1508ca2dfda 0x7d23a23584c83c1f6636124255cfd8e9cfc0e529 0x7e8b5df0dec9168741c93d52d7045aca7ea632d3 0x7ec5da0f1036750688084252b802befe41551205 0x82c9fcef4dd2d374b000063d4899a38a7219cdc7 0x82fa2ab30a566ceeac987eb5510485be9382f130 0x83d927aca3266f94e8163eaa32700c70e9b76e6e 0x8476f7e193c930f21e88dae84888e0d8bfaf3ed8 0x85ec166cb81f5010b4a8d365821473dac0c0aa88 0x8883c55943d5caf06b6484de9c1d73da8307cd82 0x8c07456cffd4254c89aaaa9d4e95c8b3e36c2a3b 0x8fef965e5db6f7f1a165008499e8b7901cd766b2 0x9018e2967c15e1faed9b5d6439522f075535a683 0x903f1d8a086c6af1afe24648b6409aade83c4340 0x9127c398827d8db6b6d5f17b71f5db69d06e8b74 0x917b5be6e3acd96d40a33c13e6748e4a88576c6d 0x91edfd05112f0bc9d6cd43b65361713a50e9eb7f 0x93026a2c4a0bc69de31515070bf086e0c1f789e5 0x94863bbbc12ec5be148f60a7020fd49236fc1937 0x94befc001e203f141462f16bde60873bcefae401 0x94c408cf5934f241d4fdd55ff3825131635c6af2 0x94cfdec548de92301735dc0b82d8e1f79404ff94 0x96527f3311f44340887c926acc16f0997eb3b955 0x974117faf194885c01513e8d87b38a2291083ed5 0x993424827a5fb2fa97818814ea4027e28150f187 0x9a6f30a5cb46840076edd780da2dbb4bc7c39f24 0x9a74a096b0bb82adfd28494107f2c07f4545723e 0x9af82ec46185641c0ea44679aac8a7e7570be202 0x9e2287a60ed85f6bd80c62c1b7b4130ea1b521dd 0x9fee5b81ee0cbf34c18c52061f1b257d4ccb2702 0xa017226377e775af8e56450301cc035ae72267f8 0xa1b423e024daf925f25296ea2efcf009cc328873 0xa23c0cbfe59e8650277ffa635c59f287cece9087 0xa340b7625eec76b372f2c317fe08a7733f05d09c 0xa4cb6be13c2eace6c0f1157553e3c446f7b38b10 0xa54326267784fae3ffd6800af38099753bb7f470 0xa580086125d040fddd3af9d563285bd0ec4d13e3 0xa88fc7a34ca36b952aa45d94c1e13155042b5e7d 0xac8f4ce2e4eff39c738bf1941350b3b57e8eec4f 0xacb17dca110db022b1aceb5399acba1e9bf577e3 0xae0b03c8d8bf9cf71eda758e9e8b59c70a3b4580 0xae365ff4b0c64413baf6f7dfdb5cd3fb65ad1376 0xaf7e60d02b425b54730b7281a97d1640233704b0 0xaf9846f8098656e7c2f0e53e9ff7d38ec7b7f679 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Rationale
EIP-161 provides that empty accounts (accounts that have zero nonce, zero balance and no code, but that might have storage) can no longer be created and provides mechanism to remove old empty accounts. The last empty accounts were removed in block 14049881 (tx 0xf955834bfa097458a9cf6b719705a443d32e7f43f20b9b0294098c205b4bcc3d
).
The complete removal of all empty accounts ensures that certain edgecases of EIP-161 can never occur on Ethereum Mainnet. Continuing to define and test those cases as part of the Ethereum Specification burdens future client implementors with unnecessary technical debt. This EIP declares those cases undefined and leaves clients free to assume they will not occur.
Backwards Compatibility
This EIP is identical to EIP-161 except for the following differences, none of which affect Ethereum Mainnet. The differences are:
"Potentially state-changing operations"
EIP-161 specifies 11 "potentially state-changing operations" that trigger state clearing. All but the 3 listed in this EIP are irrelevant, for the following reasons:
Impossible
- Receiving zero value mining reward/fees (this would become possible after the merge).
Cannot happen to an empty account
- Being the source of a
CREATE
. - Being the source of a
CALL
. - Being refunded by a
SELFDESTRUCT
Causes the account to become non-empty
- Being the sender of a message call transaction.
- Being the sender of a contract creation transaction.
- Being created by a
CREATE
. - Being created by a contract creation transaction.
Interaction with STATICCALL
The interaction between STATICCALL
and account clearing has never been specified in an EIP. The Ethereum currently testsuite requires that STATICCALL
triggers state clearing.
This EIP formally undefines all interactions between STATICCALL
and state clearing as it has never happened on Ethereum Mainnet and cannot happen in future.
"At the end of the transaction"
This only makes a difference if an account is deleted and later recreated in the same transaction. This never happens on Ethereum Mainnet.
Test Cases
All test cases involving empty accounts in the Ethereum execution layer test suite shall be removed unless they relate to the Spurious Dragon Hardfork. If a Spurious Dragon test relates involved deprecated edgecase the test must be removed or reworked.
Other networks
Ropsten had empty accounts seeded at genesis. They appear to have been cleared early in Ropsten's history before the Byzantium hardfork. Ropsten has never been checked for edgecases occurring. All other Ethereum testnets have had EIP-161 from genesis.
As a security precaution all empty accounts on Ethereum Classic have been cleared, but no checks for edgecases occurring have been done. Due to EIP-161's age the vast majority of EVM compatible networks have supported it from genesis.
Security considerations
This EIP is only equivalent to EIP-161 on Ethereum Mainnet if the following facts are true:
- No empty accounts are ever touched and then reinstated in the same transaction.
- The transactions in the Appendix are the only state clearing transactions on Ethereum Mainnet after block 4370000 (start of Byzantium).
- All empty accounts have been removed on Ethereum Mainnet.
Copyright
Copyright and related rights waived via CC0.
Adopted by projects
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