CR-UTP: Certified Robustness against Universal Text Perturbations on Large Language Models

Fuente: arXiv
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Hauptverfasser: Lou, Qian, Liang, Xin, Xue, Jiaqi, Zhang, Yancheng, Xie, Rui, Zheng, Mengxin
Format: Preprint
Veröffentlicht: 2024
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author Lou, Qian
Liang, Xin
Xue, Jiaqi
Zhang, Yancheng
Xie, Rui
Zheng, Mengxin
author_facet Lou, Qian
Liang, Xin
Xue, Jiaqi
Zhang, Yancheng
Xie, Rui
Zheng, Mengxin
contents It is imperative to ensure the stability of every prediction made by a language model; that is, a language's prediction should remain consistent despite minor input variations, like word substitutions. In this paper, we investigate the problem of certifying a language model's robustness against Universal Text Perturbations (UTPs), which have been widely used in universal adversarial attacks and backdoor attacks. Existing certified robustness based on random smoothing has shown considerable promise in certifying the input-specific text perturbations (ISTPs), operating under the assumption that any random alteration of a sample's clean or adversarial words would negate the impact of sample-wise perturbations. However, with UTPs, masking only the adversarial words can eliminate the attack. A naive method is to simply increase the masking ratio and the likelihood of masking attack tokens, but it leads to a significant reduction in both certified accuracy and the certified radius due to input corruption by extensive masking. To solve this challenge, we introduce a novel approach, the superior prompt search method, designed to identify a superior prompt that maintains higher certified accuracy under extensive masking. Additionally, we theoretically motivate why ensembles are a particularly suitable choice as base prompts for random smoothing. The method is denoted by superior prompt ensembling technique. We also empirically confirm this technique, obtaining state-of-the-art results in multiple settings. These methodologies, for the first time, enable high certified accuracy against both UTPs and ISTPs. The source code of CR-UTP is available at \url {https://github.com/UCFML-Research/CR-UTP}.
format Preprint
id arxiv_https___arxiv_org_abs_2406_01873
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle CR-UTP: Certified Robustness against Universal Text Perturbations on Large Language Models
Lou, Qian
Liang, Xin
Xue, Jiaqi
Zhang, Yancheng
Xie, Rui
Zheng, Mengxin
Computation and Language
Cryptography and Security
Machine Learning
It is imperative to ensure the stability of every prediction made by a language model; that is, a language's prediction should remain consistent despite minor input variations, like word substitutions. In this paper, we investigate the problem of certifying a language model's robustness against Universal Text Perturbations (UTPs), which have been widely used in universal adversarial attacks and backdoor attacks. Existing certified robustness based on random smoothing has shown considerable promise in certifying the input-specific text perturbations (ISTPs), operating under the assumption that any random alteration of a sample's clean or adversarial words would negate the impact of sample-wise perturbations. However, with UTPs, masking only the adversarial words can eliminate the attack. A naive method is to simply increase the masking ratio and the likelihood of masking attack tokens, but it leads to a significant reduction in both certified accuracy and the certified radius due to input corruption by extensive masking. To solve this challenge, we introduce a novel approach, the superior prompt search method, designed to identify a superior prompt that maintains higher certified accuracy under extensive masking. Additionally, we theoretically motivate why ensembles are a particularly suitable choice as base prompts for random smoothing. The method is denoted by superior prompt ensembling technique. We also empirically confirm this technique, obtaining state-of-the-art results in multiple settings. These methodologies, for the first time, enable high certified accuracy against both UTPs and ISTPs. The source code of CR-UTP is available at \url {https://github.com/UCFML-Research/CR-UTP}.
title CR-UTP: Certified Robustness against Universal Text Perturbations on Large Language Models
topic Computation and Language
Cryptography and Security
Machine Learning
url https://arxiv.org/abs/2406.01873