TrojanDec: Data-free Detection of Trojan Inputs in Self-supervised Learning

Fuente: arXiv
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Auteurs principaux: Liu, Yupei, Wang, Yanting, Jia, Jinyuan
Format: Preprint
Publié: 2025
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author Liu, Yupei
Wang, Yanting
Jia, Jinyuan
author_facet Liu, Yupei
Wang, Yanting
Jia, Jinyuan
contents An image encoder pre-trained by self-supervised learning can be used as a general-purpose feature extractor to build downstream classifiers for various downstream tasks. However, many studies showed that an attacker can embed a trojan into an encoder such that multiple downstream classifiers built based on the trojaned encoder simultaneously inherit the trojan behavior. In this work, we propose TrojanDec, the first data-free method to identify and recover a test input embedded with a trigger. Given a (trojaned or clean) encoder and a test input, TrojanDec first predicts whether the test input is trojaned. If not, the test input is processed in a normal way to maintain the utility. Otherwise, the test input will be further restored to remove the trigger. Our extensive evaluation shows that TrojanDec can effectively identify the trojan (if any) from a given test input and recover it under state-of-the-art trojan attacks. We further demonstrate by experiments that our TrojanDec outperforms the state-of-the-art defenses.
format Preprint
id arxiv_https___arxiv_org_abs_2501_04108
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle TrojanDec: Data-free Detection of Trojan Inputs in Self-supervised Learning
Liu, Yupei
Wang, Yanting
Jia, Jinyuan
Cryptography and Security
Artificial Intelligence
An image encoder pre-trained by self-supervised learning can be used as a general-purpose feature extractor to build downstream classifiers for various downstream tasks. However, many studies showed that an attacker can embed a trojan into an encoder such that multiple downstream classifiers built based on the trojaned encoder simultaneously inherit the trojan behavior. In this work, we propose TrojanDec, the first data-free method to identify and recover a test input embedded with a trigger. Given a (trojaned or clean) encoder and a test input, TrojanDec first predicts whether the test input is trojaned. If not, the test input is processed in a normal way to maintain the utility. Otherwise, the test input will be further restored to remove the trigger. Our extensive evaluation shows that TrojanDec can effectively identify the trojan (if any) from a given test input and recover it under state-of-the-art trojan attacks. We further demonstrate by experiments that our TrojanDec outperforms the state-of-the-art defenses.
title TrojanDec: Data-free Detection of Trojan Inputs in Self-supervised Learning
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2501.04108