Honest-but-Curious Nets (ACM CCS'21)

(You might also be interested in our follow-up work: https://github.com/mmalekzadeh/vicious-classifiers)

Official Paper: https://dl.acm.org/doi/10.1145/3460120.3484533

ArXiv Version: https://arxiv.org/abs/2105.12049

Title: Honest-but-Curious Nets: Sensitive Attributes of Private Inputs Can Be Secretly Coded into the Classifiers' Outputs (ACM SIGSAC Conference on Computer and Communications Security (CCS '21), November 15–19, 2021.)

Slides: https://github.com/mmalekzadeh/honest-but-curious-nets/blob/main/HBC_Nets_Slides.pdf

Presentation Video: https://www.youtube.com/watch?v=G35467ddItk

Abstract:

It is known that deep neural networks, trained for the classification of a non-sensitive target attribute, can reveal somesensitive attributes of their input data; through features of different granularity extracted by the classifier. We take a step forward and show that deep classifiers can be trained to secretly encode a sensitive attribute of users' input data into the classifier's outputs for the target attribute, at inference time. This results in an attack that works even if users have a full white-box view of the classifier, and can keep all internal representations hidden except for the classifier's outputs for the target attribute. We introduce an information-theoretical formulation of such attacks and present efficient empirical implementations for training honest-but-curious (HBC) classifiers based on this formulation: classifiers that can be accurate in predicting their target attribute, but can also exploit their outputs to secretly encode a sensitive attribute. Our evaluations on several tasks in real-world datasets show that a semi-trusted server can build a classifier that is not only perfectly honest but also accurately curious. Our work highlights a vulnerability that can be exploited by malicious machine learning service providers to attack their user's privacy in several seemingly safe scenarios; such as encrypted inferences, computations at the edge, or private knowledge distillation. We conclude by showing the difficulties in distinguishing between standard and HBC classifiers, discussing challenges in defending againstthis vulnerability of deep classifiers, and enumerating related open directions for future studies.

Dataset Prepartion

A. UTKFace

Download the Aligned&Cropped Faces from this link: https://susanqq.github.io/UTKFace/ (It is currently hosted here: https://drive.google.com/drive/folders/0BxYys69jI14kU0I1YUQyY1ZDRUE).
Unzip the file UTKFace.tar.gz in the directory hbcnets/data/, so you will have a folder named "UTKFace" (i.e. hbcnets/data/UTKFace) that includes JPEG images.
For the first time, you need to edit hbcnets/constants.py and set DATA_PREPROCESSING = 1. With this, main.py processes images and creates a .npz file for you. After that, you have to set DATA_PREPROCESSING = 0 for all the next runs, unless you change IMAGE_SIZE in hbcnets/constants.py.

B. CelebA

Download the Align&Cropped Images from this link: http://mmlab.ie.cuhk.edu.hk/projects/CelebA.html (It is currently hosted here: https://drive.google.com/drive/folders/0B7EVK8r0v71pWEZsZE9oNnFzTm8).
Create a folder named celeba in the directory hbcnets/data/.
Unzip the file img_align_celeba.zip in the folder celeba, so you will have hbcnets/data/celeba/img_align_celeba that includes JPEG images.
Download the folloowing files from the above link and put them in the folder celeba (besides folder img_align_celeba).
- list_eval_partition.txt
- list_attr_celeba.txt
- identity_CelebA.txt
For the first time, you need to edit hbcnets/constants.py and set DATA_PREPROCESSING = 1. With this, main.py processes images and creates a .npz file for you. After that, you have to set DATA_PREPROCESSING = 0 for all the next runs, unless you change IMAGE_SIZE in hbcnets/constants.py.

How to Run Experiments

This code is tested on Pytorch V 1.9.1 (use !pip install torch==1.9.1)

All you need is to run

> python main.py

But before that, it will be much helpful if you:

Make sure you have read the paper once :-)
Open hbcnets/constants.py and set up the desired setting. There are multiple parameters that you can play with (see below).
Use the arguments in setting.py for running your desired experiments.

** If you like to use Google Colab, please look at this notebook: Colab_Version_of_Main.ipynb

https://github.com/mmalekzadeh/honest-but-curious-nets/blob/main/Colab_Version_of_Main.ipynb

Experimental Setup:

In hbcnets/constants.py you can find the following parameterts:

DATASET: You can choose utk_face or celeba.
HONEST: This is the target attribut (i.e., y) in the paper. Use this to set your desired attribute.
K_Y: After setting HONEST, you need to set the size of possible values. This is Y in the paper.
CURIOUS: This is the sensitive attribut (i.e., s) in the paper. Use this to set your desired attribute.
K_S: After setting CURIOUS, you need to set the size of possible values. This is S in the paper.
BETA_X, BETA_Y, BETA_S: These are trade-off hyper-parameteres with the same name in the paper.
SOFTMAX: This allow us to decided whtehre we want to release the soft outputs (True) or the raw outputs (False).
RANDOM_SEED: You can use this alongside these lines in main.py to keep your results reproducible.
DATA_PREPROCESSING: When using a dataset for the first time, you need to set this to 1, after that it can be 0 to save time.
IMAGE_SIZE: The default is 64 (i.e., 64x64), but you can change this to get other resolutions. Notice that if you change this, you need to set DATA_PREPROCESSING=1 for the first time.

Citation

Please use:

@inproceedings{malekzadeh2021honest,
author = {Malekzadeh, Mohammad and Borovykh, Anastasia and G\"{u}nd\"{u}z, Deniz},
title = {Honest-but-Curious Nets: Sensitive Attributes of Private Inputs Can Be Secretly Coded into the Classifiers' Outputs},
year = {2021},
publisher = {Association for Computing Machinery},
doi = {10.1145/3460120.3484533},
booktitle = {Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security},
pages = {825–844},
numpages = {20},
series = {CCS '21}
}

mmalekzadeh / honest-but-curious-nets