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"""
Adversarial Examples on Graph Data: Deep Insights into Attack and Defense
https://arxiv.org/pdf/1903.01610.pdf
"""
import torch
import torch.multiprocessing as mp
from deeprobust.graph.targeted_attack import BaseAttack
from torch.nn.parameter import Parameter
from deeprobust.graph import utils
import torch.nn.functional as F
import numpy as np
import scipy.sparse as sp
from torch import optim
from torch.nn import functional as F
from torch.nn.modules.module import Module
import numpy as np
from tqdm import tqdm
import math
import scipy.sparse as sp
class IGAttack(BaseAttack):
"""IGAttack: IG-FGSM. Adversarial Examples on Graph Data: Deep Insights into Attack and Defense, https://arxiv.org/pdf/1903.01610.pdf.
Parameters
----------
model :
model to attack
nnodes : int
number of nodes in the input graph
feature_shape : tuple
shape of the input node features
attack_structure : bool
whether to attack graph structure
attack_features : bool
whether to attack node features
device: str
'cpu' or 'cuda'
Examples
--------
>>> from deeprobust.graph.data import Dataset
>>> from deeprobust.graph.defense import GCN
>>> from deeprobust.graph.targeted_attack import IGAttack
>>> data = Dataset(root='/tmp/', name='cora')
>>> adj, features, labels = data.adj, data.features, data.labels
>>> idx_train, idx_val, idx_test = data.idx_train, data.idx_val, data.idx_test
>>> # Setup Surrogate model
>>> surrogate = GCN(nfeat=features.shape[1], nclass=labels.max().item()+1,
nhid=16, dropout=0, with_relu=False, with_bias=False, device='cpu').to('cpu')
>>> surrogate.fit(features, adj, labels, idx_train, idx_val, patience=30)
>>> # Setup Attack Model
>>> target_node = 0
>>> model = IGAttack(surrogate, nnodes=adj.shape[0], attack_structure=True, attack_features=True, device='cpu').to('cpu')
>>> # Attack
>>> model.attack(features, adj, labels, idx_train, target_node, n_perturbations=5, steps=10)
>>> modified_adj = model.modified_adj
>>> modified_features = model.modified_features
"""
def __init__(self, model, nnodes=None, feature_shape=None, attack_structure=True, attack_features=True, device='cpu'):
super(IGAttack, self).__init__(model, nnodes, attack_structure, attack_features, device)
assert attack_features or attack_structure, 'attack_features or attack_structure cannot be both False'
self.modified_adj = None
self.modified_features = None
self.target_node = None
def attack(self, ori_features, ori_adj, labels, idx_train, target_node, n_perturbations, steps=10, **kwargs):
"""Generate perturbations on the input graph.
Parameters
----------
ori_features :
Original (unperturbed) node feature matrix
ori_adj :
Original (unperturbed) adjacency matrix
labels :
node labels
idx_train:
training nodes indices
target_node : int
target node index to be attacked
n_perturbations : int
Number of perturbations on the input graph. Perturbations could
be edge removals/additions or feature removals/additions.
steps : int
steps for computing integrated gradients
"""
self.surrogate.eval()
self.target_node = target_node
modified_adj = ori_adj.todense()
modified_features = ori_features.todense()
adj, features, labels = utils.to_tensor(modified_adj, modified_features, labels, device=self.device)
adj_norm = utils.normalize_adj_tensor(adj)
pseudo_labels = self.surrogate.predict().detach().argmax(1)
pseudo_labels[idx_train] = labels[idx_train]
self.pseudo_labels = pseudo_labels
s_e = np.zeros(adj.shape[1])
s_f = np.zeros(features.shape[1])
if self.attack_structure:
s_e = self.calc_importance_edge(features, adj_norm, labels, steps)
if self.attack_features:
s_f = self.calc_importance_feature(features, adj_norm, labels, steps)
for t in (range(n_perturbations)):
s_e_max = np.argmax(s_e)
s_f_max = np.argmax(s_f)
if s_e[s_e_max] >= s_f[s_f_max]:
# edge perturbation score is larger
if self.attack_structure:
value = np.abs(1 - modified_adj[target_node, s_e_max])
modified_adj[target_node, s_e_max] = value
modified_adj[s_e_max, target_node] = value
s_e[s_e_max] = 0
else:
raise Exception("""No posisble perturbation on the structure can be made!
See https://github.com/DSE-MSU/DeepRobust/issues/42 for more details.""")
else:
# feature perturbation score is larger
if self.attack_features:
modified_features[target_node, s_f_max] = np.abs(1 - modified_features[target_node, s_f_max])
s_f[s_f_max] = 0
else:
raise Exception("""No posisble perturbation on the features can be made!
See https://github.com/DSE-MSU/DeepRobust/issues/42 for more details.""")
self.modified_adj = sp.csr_matrix(modified_adj)
self.modified_features = sp.csr_matrix(modified_features)
self.check_adj(modified_adj)
def calc_importance_edge(self, features, adj_norm, labels, steps):
"""Calculate integrated gradient for edges. Although I think the the gradient should be
with respect to adj instead of adj_norm, but the calculation is too time-consuming. So I
finally decided to calculate the gradient of loss with respect to adj_norm
"""
baseline_add = adj_norm.clone()
baseline_remove = adj_norm.clone()
baseline_add.data[self.target_node] = 1
baseline_remove.data[self.target_node] = 0
adj_norm.requires_grad = True
integrated_grad_list = []
i = self.target_node
for j in tqdm(range(adj_norm.shape[1])):
if adj_norm[i][j]:
scaled_inputs = [baseline_remove + (float(k)/ steps) * (adj_norm - baseline_remove) for k in range(0, steps + 1)]
else:
scaled_inputs = [baseline_add - (float(k)/ steps) * (baseline_add - adj_norm) for k in range(0, steps + 1)]
_sum = 0
for new_adj in scaled_inputs:
output = self.surrogate(features, new_adj)
loss = F.nll_loss(output[[self.target_node]],
self.pseudo_labels[[self.target_node]])
adj_grad = torch.autograd.grad(loss, adj_norm)[0]
adj_grad = adj_grad[i][j]
_sum += adj_grad
if adj_norm[i][j]:
avg_grad = (adj_norm[i][j] - 0) * _sum.mean()
else:
avg_grad = (1 - adj_norm[i][j]) * _sum.mean()
integrated_grad_list.append(avg_grad.detach().item())
integrated_grad_list[i] = 0
# make impossible perturbation to be negative
integrated_grad_list = np.array(integrated_grad_list)
adj = (adj_norm > 0).cpu().numpy()
integrated_grad_list = (-2 * adj[self.target_node] + 1) * integrated_grad_list
integrated_grad_list[self.target_node] = -10
return integrated_grad_list
def calc_importance_feature(self, features, adj_norm, labels, steps):
"""Calculate integrated gradient for features
"""
baseline_add = features.clone()
baseline_remove = features.clone()
baseline_add.data[self.target_node] = 1
baseline_remove.data[self.target_node] = 0
features.requires_grad = True
integrated_grad_list = []
i = self.target_node
for j in tqdm(range(features.shape[1])):
if features[i][j]:
scaled_inputs = [baseline_add + (float(k)/ steps) * (features - baseline_add) for k in range(0, steps + 1)]
else:
scaled_inputs = [baseline_remove - (float(k)/ steps) * (baseline_remove - features) for k in range(0, steps + 1)]
_sum = 0
for new_features in scaled_inputs:
output = self.surrogate(new_features, adj_norm)
loss = F.nll_loss(output[[self.target_node]],
self.pseudo_labels[[self.target_node]])
feature_grad = torch.autograd.grad(loss, features)[0]
feature_grad = feature_grad[i][j]
_sum += feature_grad
if features[i][j]:
avg_grad = (features[i][j] - 0) * _sum.mean()
else:
avg_grad = (1 - features[i][j]) * _sum.mean()
integrated_grad_list.append(avg_grad.detach().item())
# make impossible perturbation to be negative
features = (features > 0).cpu().numpy()
integrated_grad_list = np.array(integrated_grad_list)
integrated_grad_list = (-2 * features[self.target_node] + 1) * integrated_grad_list
return integrated_grad_list
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