lmdk_lib: Randomized response

code/lib/lmdk_lib.py

@@ -48,6 +48,26 @@ def add_polar_noise(loc, epsilon):
   return new_loc
 
 
+def randomized_response(r, epsilon):
+  '''
+    Return the original response with probability p,
+    or flip the response with probability 1 - p.
+    [https://www.usenix.org/system/files/conference/usenixsecurity17/sec17-wang-tianhao.pdf]
+
+    Parameters:
+      r       - The original response (True/False).
+      epsilon - The privacy budget.
+    Returns:
+      The randomized response.
+  '''
+  # Return the original value
+  if random.uniform(0, 1) <= math.exp(epsilon)/(math.exp(epsilon) + 1):
+    return r
+  # Flip the original value
+  else:
+    return not r
+
+
 def draw_line(line, x, label, marker):
   axis_x = list(range(len(x)))
   # plt.xticks(axis_x, x)