mirror of https://github.com/status-im/EIPs.git
37 lines
1.5 KiB
Markdown
37 lines
1.5 KiB
Markdown
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---
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eip: 1052
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title: EXTCODEHASH opcode
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author: Nick Johnson <arachnid@notdot.net>
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discussions-to: https://ethereum-magicians.org/t/extcodehash-opcode/262
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status: Draft
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type: Standards Track
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category: Core
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created: 2018-05-02
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---
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## Abstract
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This EIP specifies a new opcode, which returns the keccak256 hash of a contract's code.
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## Motivation
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Many contracts need to perform checks on a contract's bytecode, but do not necessarily need the bytecode itself. For instance, a contract may want to check if another contract's bytecode is one of a set of permitted implementations, or it may perform analyses on code and whitelist any contract with matching bytecode if the analysis passes.
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Contracts can presently do this using the `EXTCODECOPY` opcode, but this is expensive, especially for large contracts, in cases where only the hash is required. As a result, we propose a new opcode, `EXTCODEHASH`, which returns the keccak256 hash of a contract's bytecode.
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## Specification
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A new opcode, `EXTCODEHASH`, is introduced, with number 0x3D. `EXTCODEHASH` takes one argument from the stack, and pushes the keccak256 hash of the code at that address to the stack.
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## Rationale
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As described in the motivation section, this opcode is widely useful, and saves on wasted gas in many cases.
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## Backwards Compatibility
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There are no backwards compatibility concerns.
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## Test Cases
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TBD
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## Implementation
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TBD
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## Copyright
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Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
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