def _gradient(self, inputs, labels):
"""
Calculate the gradient of input samples.
Args:
inputs (Union[numpy.ndarray, tuple]): Input samples.
labels (Union[numpy.ndarray, tuple]): Original/target labels. \
For each input if it has more than one label, it is wrapped in a tuple.
Returns:
numpy.ndarray, gradient of labels w.r.t inputs.
Examples:
>>> grad = self._gradient([[0.5, 0.3, 0.4]],
>>> [[0, 0, 0, 1, 0, 0, 0, 0, 0, 0])
"""
# get grad of loss over x
inputs_tensor = to_tensor_tuple(inputs)
labels_tensor = to_tensor_tuple(labels)
out_grad = self._loss_grad(*inputs_tensor, *labels_tensor)
if isinstance(out_grad, tuple):
out_grad = out_grad[0]
gradient = out_grad.asnumpy()
if self._is_targeted:
gradient = -gradient
return normalize_value(gradient, self._norm_level)
def _projection(values, eps, norm_level):
"""
Implementation of values normalization within eps.
Args:
values (numpy.ndarray): Input data.
eps (float): Project radius.
norm_level (Union[int, char, numpy.inf]): Order of the norm. Possible
values: np.inf, 1 or 2.
Returns:
numpy.ndarray, normalized values.
Raises:
NotImplementedError: If the norm_level is not in [1, 2, np.inf, '1',
'2', 'inf'].
"""
if norm_level in (1, '1'):
sample_batch = values.shape[0]
x_flat = values.reshape(sample_batch, -1)
proj_flat = _reshape_l1_projection(x_flat, eps)
return proj_flat.reshape(values.shape)
if norm_level in (2, '2'):
return eps * normalize_value(values, norm_level)
if norm_level in (np.inf, 'inf'):
return eps * np.sign(values)
msg = 'Values of `norm_level` different from 1, 2 and `np.inf` are ' \
'currently not supported.'
LOGGER.error(TAG, msg)
raise NotImplementedError(msg)
def _gradient(self, inputs, labels):
"""
Calculate the gradient of input samples.
Args:
inputs (numpy.ndarray): Input samples.
labels (numpy.ndarray): Original/target labels.
Returns:
numpy.ndarray, gradient of labels w.r.t inputs.
Examples:
>>> grad = self._gradient([[0.5, 0.3, 0.4]],
>>> [[0, 0, 0, 1, 0, 0, 0, 0, 0, 0])
"""
sens = Tensor(np.array([1.0], inputs.dtype))
# get grad of loss over x
out_grad = self._loss_grad(Tensor(inputs), Tensor(labels), sens)
if isinstance(out_grad, tuple):
out_grad = out_grad[0]
gradient = out_grad.asnumpy()
if self._is_targeted:
gradient = -gradient
return normalize_value(gradient, self._norm_level)
def _gradient(self, inputs, labels):
"""
Calculate gradients based on input samples and original/target labels.
Args:
inputs (numpy.ndarray): Input sample.
labels (Union[numpy.ndarray, tuple]): Original/target labels. \
For each input if it has more than one label, it is wrapped in a tuple.
Returns:
numpy.ndarray, gradient of inputs.
"""
if isinstance(labels, tuple):
labels_tensor = tuple()
for item in labels:
labels_tensor += (Tensor(item), )
else:
labels_tensor = (Tensor(labels), )
out_grad = self._grad_all(Tensor(inputs), *labels_tensor)
if isinstance(out_grad, tuple):
out_grad = out_grad[0]
gradient = out_grad.asnumpy()
if self._is_targeted:
gradient = -gradient
return normalize_value(gradient, self._norm_level)
def _gradient(self, inputs, labels):
"""
Calculate gradients based on input samples and original/target labels.
Args:
inputs (numpy.ndarray): Input sample.
labels (numpy.ndarray): Original/target label.
Returns:
numpy.ndarray, gradient of inputs.
"""
out_grad = self._grad_all(Tensor(inputs), Tensor(labels))
if isinstance(out_grad, tuple):
out_grad = out_grad[0]
gradient = out_grad.asnumpy()
if self._is_targeted:
gradient = -gradient
return normalize_value(gradient, self._norm_level)
def _gradient(self, inputs, labels):
"""
Calculate gradients based on input samples and original/target labels.
Args:
inputs (numpy.ndarray): Input sample.
labels (numpy.ndarray): Original/target label.
Returns:
numpy.ndarray, gradient of inputs.
Examples:
>>> grad = self._gradient([[0.2, 0.3, 0.4]],
>>> [[0, 1, 0, 0, 0, 0, 0, 0, 0, 0])
"""
sens = Tensor(np.array([1.0], self._dtype))
out_grad = self._grad_all(Tensor(inputs), Tensor(labels), sens)
if isinstance(out_grad, tuple):
out_grad = out_grad[0]
gradient = out_grad.asnumpy()
if self._is_targeted:
gradient = -gradient
return normalize_value(gradient, self._norm_level)
def _generate_one(self, one_input, label, epsilons=10):
"""
Increases the amount of salt and pepper noise to generate adversarial
samples.
Args:
one_input (numpy.ndarray): The original, unperturbed input.
label (numpy.ndarray): The target label.
epsilons (int) : Number of steps to try probability between 0
and 1. Default: 10
Returns:
- numpy.ndarray, bool values for result.
- numpy.ndarray, adversarial example.
- numpy.ndarray, query times for this sample.
Examples:
>>> one_adv = self._generate_one(input, label)
"""
# use binary search to get epsilons
low_ = 0.0
high_ = 1.0
query_count = 0
input_shape = one_input.shape
input_dtype = one_input.dtype
one_input = one_input.reshape(-1)
depth = np.abs(np.subtract(self._bounds[0], self._bounds[1]))
best_adv = np.copy(one_input)
best_eps = high_
find_adv = False
for _ in range(self._max_iter):
min_eps = low_
max_eps = (low_ + high_) / 2
for _ in range(epsilons):
adv = np.copy(one_input)
noise = np.random.uniform(low=low_, high=high_, size=one_input.size)
eps = (min_eps + max_eps) / 2
# add salt
adv[noise < eps] = -depth
# add pepper
adv[noise >= (high_ - eps)] = depth
# normalized sample
adv = normalize_value(np.expand_dims(adv, axis=0), 'l2').astype(input_dtype)
query_count += 1
ite_bool = self._model.is_adversarial(adv.reshape(input_shape),
label,
is_targeted=self._is_targeted)
if ite_bool:
find_adv = True
if best_eps > eps:
best_adv = adv
best_eps = eps
max_eps = eps
LOGGER.debug(TAG, 'Attack succeed, epsilon is {}'.format(eps))
else:
min_eps = eps
if find_adv:
break
return find_adv, best_adv.reshape(input_shape), query_count
