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|
from typing import (
Union,
)
from .abc import (
BackendAPI,
PreImageAPI,
)
class Keccak256:
def __init__(self, backend: BackendAPI) -> None:
self._backend = backend
self.hasher = self._hasher_first_run
self.preimage = self._preimage_first_run
def _hasher_first_run(self, in_data: Union[bytearray, bytes]) -> bytes:
"""
Validate, on first-run, that the hasher backend is valid.
After first run, replace this with the new hasher method.
This is a bit of a hacky way to minimize overhead on hash calls after
this first one.
"""
# Execute directly before saving method,
# to let any side-effects settle (see AutoBackend)
result = self._backend.keccak256(in_data)
new_hasher = self._backend.keccak256
assert (
new_hasher(b"")
== b"\xc5\xd2F\x01\x86\xf7#<\x92~}\xb2\xdc\xc7\x03\xc0\xe5\x00\xb6S\xca\x82';\x7b\xfa\xd8\x04]\x85\xa4p" # noqa: E501
)
self.hasher = new_hasher
return result
def _preimage_first_run(self, in_data: Union[bytearray, bytes]) -> PreImageAPI:
# Execute directly before saving method,
# to let any side-effects settle (see AutoBackend)
result = self._backend.preimage(in_data)
self.preimage = self._backend.preimage
return result
def __call__(self, preimage: Union[bytearray, bytes]) -> bytes:
if not isinstance(preimage, (bytearray, bytes)):
raise TypeError(
"Can only compute the hash of `bytes` or `bytearray` values, "
f"not {repr(preimage)}"
)
return self.hasher(preimage)
def new(self, preimage: Union[bytearray, bytes]) -> PreImageAPI:
if not isinstance(preimage, (bytearray, bytes)):
raise TypeError(
"Can only compute the hash of `bytes` or `bytearray` values, "
f"not {repr(preimage)}"
)
return self.preimage(preimage)
|
