use hashlib `keccak256()` function if available

Available if Python compiled with OpenSSL 3.2 or greater (Python >= 3.13)

mmgen/util2.py

@@ -55,6 +55,14 @@ def load_cryptodome(called=[]):
 			sys.modules['Cryptodome'] = Crypto # Cryptodome == pycryptodomex
 		called.append(True)
 
+def get_hashlib_keccak():
+	import hashlib
+	try:
+		hashlib.new('keccak-256')
+	except ValueError:
+		return False
+	return lambda data: hashlib.new('keccak-256', data)
+
 # called with no arguments by proto.eth.tx.transaction:
 def get_keccak(cfg=None, cached_ret=[]):
 
@@ -62,11 +70,10 @@ def get_keccak(cfg=None, cached_ret=[]):
 		if cfg and cfg.use_internal_keccak_module:
 			cfg._util.qmsg('Using internal keccak module by user request')
 			from .contrib.keccak import keccak_256
-		else:
+		elif not (keccak_256 := get_hashlib_keccak()):
 			load_cryptodome()
 			from Crypto.Hash import keccak
-			def keccak_256(data):
-				return keccak.new(data=data, digest_bytes=32)
+			keccak_256 = lambda data: keccak.new(data=data, digest_bytes=32)
 		cached_ret.append(keccak_256)
 
 	return cached_ret[0]

test/gentest.py

@@ -593,7 +593,7 @@ vmsg = cfg._util.vmsg
 
 proto = cfg._proto
 
-if proto.coin in ('XMR', 'ETH', 'ETC'):
+if proto.coin == 'XMR':
 	from mmgen.util2 import load_cryptodome
 	load_cryptodome()
 

test/modtest_d/dep.py

@@ -44,16 +44,19 @@ class unit_tests:
 			gmsg('LED support found!')
 		return True
 
-	def keccak(self, name, ut): # used by ETH, XMR
-		from mmgen.util2 import get_keccak
-		try:
-			keccak_256 = get_keccak()
-			keccak_256(b'abc')
-		except Exception as e:
-			rmsg(str(e))
-			return False
-		else:
-			return True
+	def keccak(self, name, ut): # used by ETH, ETC, XMR
+		from mmgen.util2 import get_keccak, get_hashlib_keccak
+		if not (keccak_256 := get_hashlib_keccak()):
+			ymsg('Hashlib keccak_256() not available, falling back on cryptodome(x) package')
+			try:
+				keccak_256 = get_keccak()
+			except Exception as e:
+				rmsg(str(e))
+				return False
+
+		chk = 'c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470'
+		assert keccak_256(b'').hexdigest() == chk, 'hash mismatch!'
+		return True
 
 	def pysocks(self, name, ut):
 		import requests, urllib3