Merge pull request #17 from carver/update-after-digest

Update after digest

eth_hash/backends/pycryptodome.py

@@ -1,6 +1,7 @@
 from Crypto.Hash import (
     keccak,
 )
+
 from eth_hash.preimage import (
     BasePreImage,
 )
@@ -15,7 +16,7 @@ class preimage(BasePreImage):
     _hash = None
 
     def __init__(self, prehash) -> None:
-        self._hash = keccak.new(data=prehash, digest_bits=256)
+        self._hash = keccak.new(data=prehash, digest_bits=256, update_after_digest=True)
         # pycryptodome doesn't expose a `copy` mechanism for it's hash objects
         # so we keep a record of all of the parts for when/if we need to copy
         # them.

eth_hash/backends/pysha3.py

@@ -1,10 +1,11 @@
-from eth_hash.preimage import (
-    BasePreImage,
-)
 from sha3 import (
     keccak_256 as _keccak_256,
 )
 
+from eth_hash.preimage import (
+    BasePreImage,
+)
+
 
 def keccak256(prehash: bytes) -> bytes:
     return _keccak_256(prehash).digest()

tests/backends/test_results.py

@@ -80,3 +80,11 @@ def test_copy_keccak_256_preimage(keccak):
 
     assert preimage_origin.digest() == b"\xb1\xf3T\xb2\x8f\xf2\x84R\xd6\xb9\xd6\x1fA\x06\x1b\xbe\x82\xbe\xb1\xfc\x98\xf33d\xa8\x05\x8d\x1a]\x16M\x05"  # noqa: E501
     assert preimage_copy.digest() == 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
+
+
+def test_update_digest_update(keccak):
+    preimage = keccak.new(b'')
+    preimage.update(b'arst')
+    assert preimage.digest() == b"\xc30[\xc9\xde\x12D\xe4\x80P\x96,\xedP\xb7Y4\xc3p\x06\xe9\x9e\x8bzb!>\x94\\=\xfc\xd7"  # noqa: E501
+    preimage.update(b'tsra')
+    assert preimage.digest() == b"\xb1\xf3T\xb2\x8f\xf2\x84R\xd6\xb9\xd6\x1fA\x06\x1b\xbe\x82\xbe\xb1\xfc\x98\xf33d\xa8\x05\x8d\x1a]\x16M\x05"  # noqa: E501

tox.ini

@@ -12,6 +12,7 @@ force_sort_within_sections=True
 include_trailing_comma=True
 known_standard_library=pytest
 known_first_party=eth_hash
+known_third_party=Crypto,sha3
 line_length=21
 multi_line_output=3
 use_parentheses=True