BTC Symbolic EXecution: Minor changes

	* Testing timeout raised to 30 s
	* Bug fix for RIPEMD160 which can no longer be imported from
	  hashlib
	* Bug fix: some scripts were badly parsed when no else clauses
were present

symbolic_execution/hardware/machines/btc_machine.py

 """Implementation of a stack-based machine able to run Bitcoin scripts."""
 from copy import deepcopy
 import hashlib
-from Crypto.Hash import RIPEMD160
 from math import ceil, floor, log2
 from typing import Any, Callable, Dict, List, Tuple
 from symbolic_execution.hardware.memory.ram import Word
@@ -98,9 +97,9 @@ def int_to_bytes(val: int) -> str:
 CHECK_SINGLE_SIG = Function("check_sig", IntSort(), IntSort(), BoolSort())
 CHECK_MULTI_SIG = Function("check_multi_sig", IntSort(), IntSort(), BoolSort())
 HASH_FUNCTIONS = {
-    "ripemd160": [Function("ripemd160", IntSort(), IntSort()), RIPEMD160.new, 20],
-    "sha1": [Function("sha1", IntSort(), IntSort()), hashlib.sha1, 20],
-    "sha256": [Function("sha256", IntSort(), IntSort()), hashlib.sha256, 32],
+    "ripemd160": [Function("ripemd160", IntSort(), IntSort()), hashlib.new, 20],
+    "sha1": [Function("sha1", IntSort(), IntSort()), hashlib.new, 20],
+    "sha256": [Function("sha256", IntSort(), IntSort()), hashlib.new, 32],
 }
 
 
@@ -293,7 +292,7 @@ class BTCVector:
 
         def hash_of_vector(btcVector):
             if is_int_value(btcVector.val):
-                m = py_function(int_to_bytes(simplify(btcVector.val).as_long()))
+                m = py_function(hash_function_name, int_to_bytes(simplify(btcVector.val).as_long()))
                 h = m.hexdigest()
                 return BTCVector(IntVal(str_to_int(h)), IntVal(hash_size))
             else:

symbolic_execution/language/bitcoin/parser.py

@@ -177,7 +177,7 @@ class BitcoinParser(ILanguage):
                             tokens["ELSE_CLAUSES"],
                         )
                     )
-                    if "ELSE_CLAUSES" in tokens
+                    if len(tokens["ELSE_CLAUSES"]) > 0
                     else [InstructionBlock()]
                 )
 

tests/language/bitcoin/test_parser.py

@@ -92,7 +92,7 @@ class TestParser(unittest.TestCase):
     def test_symbolic_execution(self):
         for _, scenario in enumerate(SYMBOLIC_TESTING_SCENARII):
             with self.subTest(scenario.hex_script):
-                _, status = find_unlocking_script(scenario.hex_script, timeout=10)
+                _, status = find_unlocking_script(scenario.hex_script, timeout=30)
                 self.assertEqual(status, scenario.execution_status)