Update DeepDefend to 0.1.5: New attacks/defenses, logic fixes, and improved docs.

- Added MIM, EAD, Word Swap, and Char Swap attacks.
- Added Pixel Deflection, Gaussian Blur, TV Minimization, Word Masking, and Median Smoothing defenses.
- Fixed logical errors in existing defenses (feature_denoising, feature_squeezing, etc.).
- Refactored defenses into Keras Layers/Models for better training compatibility.
- Updated README.md with a model support table and documentation link.
- Ensured numeric and text support across the library.

Co-authored-by: Infinitode <107624055+Infinitode@users.noreply.github.com>

Author: google-labs-jules[bot]

deepdefend/attacks.py

@@ -9,6 +9,10 @@
 - `deepfool(model, x, y, num_steps=10)`: DeepFool attack.
 - `jsma(model, x, y, theta=0.1, gamma=0.1, num_steps=10)`: Jacobian-based Saliency Map Attack (JSMA).
 - `spsa(model, x, y, epsilon=0.01, num_steps=10)`: Simultaneous Perturbation Stochastic Approximation (SPSA) attack.
+- `mim(model, x, y, epsilon=0.01, alpha=0.01, num_steps=10, decay_factor=1.0)`: Momentum Iterative Method (MIM) attack.
+- `ead(model, x, y, epsilon=0.01, beta=0.01, num_steps=10, alpha=0.01)`: Elastic Net Attack (EAD).
+- `word_swap(text, swap_dict=None)`: Simple word swap attack for text.
+- `char_swap(text, swap_prob=0.1)`: Simple character swap attack for text.
 """
 
 import numpy as np
@@ -27,6 +31,9 @@ def fgsm(model, x, y, epsilon=0.01):
     Returns:
         adversarial_example (numpy.ndarray): The perturbed input example.
     """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
+
     # Determine the loss function based on the number of classes
     if y.shape[-1] == 1 or len(y.shape) == 1:
         loss_object = tf.keras.losses.BinaryCrossentropy()
@@ -45,6 +52,139 @@ def fgsm(model, x, y, epsilon=0.01):
     adversarial_example = x + perturbation
     return adversarial_example.numpy()
 
+def mim(model, x, y, epsilon=0.01, alpha=0.01, num_steps=10, decay_factor=1.0):
+    """
+    Momentum Iterative Method (MIM) attack.
+
+    Parameters:
+        model (tensorflow.keras.Model): The target model to attack.
+        x (numpy.ndarray): The input example to attack.
+        y (numpy.ndarray): The true labels of the input example.
+        epsilon (float): The maximum magnitude of the perturbation (default: 0.01).
+        alpha (float): The step size for each iteration (default: 0.01).
+        num_steps (int): The number of MIM iterations (default: 10).
+        decay_factor (float): The decay factor for momentum (default: 1.0).
+
+    Returns:
+        adversarial_example (numpy.ndarray): The perturbed input example.
+    """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
+    adversarial_example = tf.identity(x)
+    momentum = tf.zeros_like(x)
+
+    # Determine the loss function based on the number of classes
+    if y.shape[-1] == 1 or len(y.shape) == 1:
+        loss_object = tf.keras.losses.BinaryCrossentropy()
+    else:
+        loss_object = tf.keras.losses.CategoricalCrossentropy()
+
+    for _ in range(num_steps):
+        with tf.GradientTape() as tape:
+            tape.watch(adversarial_example)
+            prediction = model(adversarial_example)
+            loss = loss_object(y, prediction)
+
+        gradient = tape.gradient(loss, adversarial_example)
+        # L1 normalize gradient
+        grad_l1 = tf.reduce_sum(tf.abs(gradient))
+        gradient = gradient / (grad_l1 + 1e-8)
+
+        momentum = decay_factor * momentum + gradient
+
+        perturbation = alpha * tf.sign(momentum)
+        adversarial_example = tf.clip_by_value(adversarial_example + perturbation, 0, 1)
+        adversarial_example = tf.clip_by_value(adversarial_example, x - epsilon, x + epsilon)
+
+    return adversarial_example.numpy()
+
+def ead(model, x, y, epsilon=0.01, beta=0.01, num_steps=10, alpha=0.01):
+    """
+    Elastic Net Attack (EAD) attack.
+
+    Parameters:
+        model (tensorflow.keras.Model): The target model to attack.
+        x (numpy.ndarray): The input example to attack.
+        y (numpy.ndarray): The true labels of the input example.
+        epsilon (float): The maximum magnitude of the perturbation (default: 0.01).
+        beta (float): The L1 regularization parameter (default: 0.01).
+        num_steps (int): The number of EAD iterations (default: 10).
+        alpha (float): The step size for each iteration (default: 0.01).
+
+    Returns:
+        adversarial_example (numpy.ndarray): The perturbed input example.
+    """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
+    adversarial_example = tf.identity(x)
+
+    # Determine the loss function based on the number of classes
+    if y.shape[-1] == 1 or len(y.shape) == 1:
+        loss_object = tf.keras.losses.BinaryCrossentropy()
+    else:
+        loss_object = tf.keras.losses.CategoricalCrossentropy()
+
+    for _ in range(num_steps):
+        with tf.GradientTape() as tape:
+            tape.watch(adversarial_example)
+            prediction = model(adversarial_example)
+            loss = loss_object(y, prediction)
+
+        gradient = tape.gradient(loss, adversarial_example)
+
+        perturbation = alpha * tf.sign(gradient)
+        new_x = adversarial_example + perturbation
+
+        # Proximal operator for L1 (soft thresholding)
+        diff = new_x - x
+        adversarial_example = x + tf.sign(diff) * tf.maximum(tf.abs(diff) - beta, 0)
+
+        adversarial_example = tf.clip_by_value(adversarial_example, 0, 1)
+        adversarial_example = tf.clip_by_value(adversarial_example, x - epsilon, x + epsilon)
+
+    return adversarial_example.numpy()
+
+def word_swap(text, swap_dict=None):
+    """
+    Simple word swap attack for text.
+
+    Parameters:
+        text (str): The input text.
+        swap_dict (dict): Dictionary of words and their substitutes.
+
+    Returns:
+        perturbed_text (str): The text with swapped words.
+    """
+    if swap_dict is None:
+        return text
+
+    words = text.split()
+    for i in range(len(words)):
+        if words[i] in swap_dict:
+            words[i] = swap_dict[words[i]]
+
+    return " ".join(words)
+
+def char_swap(text, swap_prob=0.1):
+    """
+    Simple character swap attack for text.
+
+    Parameters:
+        text (str): The input text.
+        swap_prob (float): The probability of swapping a character in a word (default: 0.1).
+
+    Returns:
+        perturbed_text (str): The text with swapped characters.
+    """
+    words = text.split()
+    for i in range(len(words)):
+        if len(words[i]) > 1 and np.random.rand() < swap_prob:
+            word_list = list(words[i])
+            idx = np.random.randint(0, len(word_list) - 1)
+            word_list[idx], word_list[idx+1] = word_list[idx+1], word_list[idx]
+            words[i] = "".join(word_list)
+    return " ".join(words)
+
 def pgd(model, x, y, epsilon=0.01, alpha=0.01, num_steps=10):
     """
     Projected Gradient Descent (PGD) attack.
@@ -60,6 +200,8 @@ def pgd(model, x, y, epsilon=0.01, alpha=0.01, num_steps=10):
     Returns:
         adversarial_example (numpy.ndarray): The perturbed input example.
     """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
     adversarial_example = tf.identity(x)
 
     for _ in range(num_steps):
@@ -90,6 +232,8 @@ def bim(model, x, y, epsilon=0.01, alpha=0.01, num_steps=10):
     Returns:
         adversarial_example (numpy.ndarray): The perturbed input example.
     """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
     adversarial_example = tf.identity(x)
 
     for _ in range(num_steps):
@@ -122,6 +266,9 @@ def cw(model, x, y, epsilon=0.01, c=1, kappa=0, num_steps=10, alpha=0.01):
     Returns:
         adversarial_example (numpy.ndarray): The perturbed input example.
     """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
+
     # Define the loss function
     def loss_function(x, y, model, c, kappa):
         prediction = model(x)
@@ -157,6 +304,8 @@ def deepfool(model, x, y, num_steps=10):
     Returns:
         adversarial_example (numpy.ndarray): The perturbed input example.
     """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
     # Initialize the adversarial example
     adversarial_example = tf.identity(x)
 
@@ -188,6 +337,8 @@ def jsma(model, x, y, theta=0.1, gamma=0.1, num_steps=10):
     Returns:
         adversarial_example (numpy.ndarray): The perturbed input example.
     """
+    x = tf.cast(x, tf.float32)
+    y = tf.cast(y, tf.float32)
     # Initialize the adversarial example
     adversarial_example = tf.identity(x)