def cpa_attack_trace_set(trace_set, result, conf):
if result.guess_sample_score_matrix is None:
raise EMMAException("Score matrix is not initialized.")
if not trace_set.windowed:
logger.warning("Trace set not windowed. Skipping attack.")
return
if trace_set.num_traces <= 0:
logger.warning("Skipping empty trace set.")
return
hypotheses = np.empty([256, trace_set.num_traces])
# 1. Build hypotheses for all 256 possibilities of the key and all traces
leakage_model = LeakageModel(conf)
for subkey_guess in range(0, 256):
for i in range(0, trace_set.num_traces):
hypotheses[subkey_guess, i] = leakage_model.get_trace_leakages(
trace=trace_set.traces[i],
subkey_start_index=conf.subkey,
key_hypothesis=subkey_guess)
# 2. Given point j of trace i, calculate the correlation between all hypotheses
for j in range(0, trace_set.window.size):
# Get measurements (columns) from all traces
measurements = np.empty(trace_set.num_traces)
for i in range(0, trace_set.num_traces):
measurements[i] = trace_set.traces[i].signal[j]
# Correlate measurements with 256 hypotheses
for subkey_guess in range(0, 256):
# Update correlation
result.guess_sample_score_matrix.update(
(subkey_guess, j), hypotheses[subkey_guess, :], measurements)
def test_hmac_hw(self):
fake_pt = np.array([0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08], dtype=np.uint8)
fake_key = np.array([0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80], dtype=np.uint8)
trace = Trace(signal=[], plaintext=fake_pt, ciphertext=[], key=fake_key, mask=[])
lm = LeakageModel(Namespace(leakage_model="hmac_hw", key_low=0, key_high=1))
self.assertEqual(lm.subkey_size, 4) # HMAC uses subkeys of size 4
leakage_subkey_0 = lm.get_trace_leakages(trace, 0) # hw32(0x40302010)
leakage_subkey_1 = lm.get_trace_leakages(trace, 1) # hw32(0x80706050)
self.assertEqual(leakage_subkey_0[0], hw32(0x40302010))
self.assertEqual(leakage_subkey_1[0], hw32(0x80706050))
self.assertEqual(leakage_subkey_0[1], hw32(0x40302010 ^ 0x36363636))
self.assertEqual(leakage_subkey_1[1], hw32(0x80706050 ^ 0x36363636))
self.assertEqual(leakage_subkey_0[2], hw32(0x40302010 ^ 0x5c5c5c5c))
self.assertEqual(leakage_subkey_1[2], hw32(0x80706050 ^ 0x5c5c5c5c))
class SignalLeakageAIInput(AIInput):
input_type = AIInputType.SIGNAL_LEAKAGE
def __init__(self, conf):
super().__init__(conf)
self.leakage_model = LeakageModel(conf)
def get_trace_inputs(self, trace):
leakages = []
for k in range(16):
leakage = self.leakage_model.get_trace_leakages(trace, k)
if isinstance(leakage, list) or isinstance(leakage, np.ndarray):
leakages.extend(list(leakage))
else:
leakages.append(leakage)
leakages = np.array(leakages)
return np.concatenate((trace.signal, leakages))