ethereum.forks.amsterdam.vm.instructions.keccak

Ethereum Virtual Machine (EVM) Keccak Instructions.

.. contents:: Table of Contents :backlinks: none :local:

Introduction

Implementations of the EVM keccak instructions.

keccak

Pushes to the stack the Keccak-256 hash of a region of memory.

This also expands the memory, in case the memory is insufficient to access the data's memory location.

Parameters

evm : The current EVM frame.

def keccak(​evm: Evm​) -> None:
30
    """
31
    Pushes to the stack the Keccak-256 hash of a region of memory.
32
33
    This also expands the memory, in case the memory is insufficient to
34
    access the data's memory location.
35
36
    Parameters
37
    ----------
38
    evm :
39
        The current EVM frame.
40
41
    """
42
    # STACK
43
    memory_start_index = pop(evm.stack)
44
    size = pop(evm.stack)
45
46
    # GAS
47
    words = ceil32(Uint(size)) // Uint(32)
48
    word_gas_cost = GasCosts.OPCODE_KECCACK256_PER_WORD * words
49
    extend_memory = calculate_gas_extend_memory(
50
        evm.memory, [(memory_start_index, size)]
51
    )
52
    charge_gas(
53
        evm,
54
        GasCosts.OPCODE_KECCAK256_BASE + word_gas_cost + extend_memory.cost,
55
    )
56
57
    # OPERATION
58
    evm.memory += b"\x00" * extend_memory.expand_by
59
    data = memory_read_bytes(evm.memory, memory_start_index, size)
60
    hashed = keccak256(data)
61
62
    push(evm.stack, U256.from_be_bytes(hashed))
63
64
    # PROGRAM COUNTER
65
    evm.pc += Uint(1)