def check_whether_random_plaintexts_affect_key_dependencies(self, n=10):
"""
Test function that checks whether we can determine the key dependencies in a pre-processing step when assuming
that the plaintext is constant. This is checked by observing whether the key dependencies change if the plain-
text is changed in a random manner.
:return:
"""
tested = set()
static_pt_dependency_graph = DependencyGraph(
DependencyGraphKey.KEY,
name="Static-plaintext key dependency graph")
dynamic_pt_dependency_graph = DependencyGraph(
DependencyGraphKey.KEY,
name="Dynamic-plaintext key dependency graph")
zero_key = b"\x00" * self.key_meta.length
zero_plaintext = b"\x00" * self.plaintext_meta.length
clean_state = X64EmulationState(self.elf)
clean_state.write_symbol(self.key_meta.symbol_name, zero_key)
clean_state.write_symbol(self.plaintext_meta.symbol_name,
zero_plaintext)
clean_state.write_register(UC_X86_REG_RSP, self.elf.sp)
# Create reference state: this state will contain a key with all bits zero during the execution
ref_state = clean_state.copy()
emulate(ref_state, self.elf.get_symbol_address('stop'),
self.num_instructions)
for b in range(0, self.key_meta.length * 8):
key = binascii.unhexlify(
("%0" + str(self.key_meta.length * 2) + "x") % (1 << b))
dyn_pt = random_uniform(self.plaintext_meta.length)
# Flip bit of key but keep static plaintext
static_pt_state = clean_state.copy()
static_pt_state.write_symbol(self.key_meta.symbol_name, key)
# Emulate and diff
emulate(static_pt_state, self.elf.get_symbol_address('stop'),
self.num_instructions)
static_pt_state.diff(ref_state, b, 0, static_pt_dependency_graph)
# Flip bit of key but also change plaintext
dyn_pt_state = clean_state.copy()
dyn_pt_state.write_symbol(self.key_meta.symbol_name, key)
dyn_pt_state.write_symbol(self.plaintext_meta.symbol_name, dyn_pt)
# Emulate and diff
emulate(dyn_pt_state, self.elf.get_symbol_address('stop'),
self.num_instructions)
dyn_pt_state.diff(ref_state, b, 0, dynamic_pt_dependency_graph)
eq = static_pt_dependency_graph.has_same_deps(
dynamic_pt_dependency_graph)
if eq is False:
print("-------Found not equal at bit %d:" % b)
print_numpy_as_hex(np.array(bytearray(key)), "Key")
print_numpy_as_hex(np.array(bytearray(dyn_pt)), "Plaintext")
tested.add((key, dyn_pt))
print("Tested:")
print(tested)
print("Done!")
