Locket: Robust Feature-Locking Technique for Language Models

Fuente: arXiv
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Autori principali: He, Lipeng, Duddu, Vasisht, Asokan, N.
Natura: Preprint
Pubblicazione: 2025
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author He, Lipeng
Duddu, Vasisht
Asokan, N.
author_facet He, Lipeng
Duddu, Vasisht
Asokan, N.
contents Chatbot service providers (e.g., OpenAI) rely on tiered subscription plans to generate revenue, offering black-box access to basic models for free users and advanced models to paying subscribers. However, this approach is unprofitable and inflexible. A pay-to-unlock scheme for premium features (e.g., math, coding) offers a more sustainable alternative. Enabling such a scheme requires a feature-locking technique (FLoTE) that is (i) effective in refusing locked features, (ii) utility-preserving for unlocked features, (iii) robust against evasion or unauthorized credential sharing, and (iv) scalable to multiple features and clients. Existing FLoTEs (e.g., password-locked models) fail to meet these criteria. To fill this gap, we present Locket, the first robust and scalable FLoTE to enable pay-to-unlock schemes. We develop a framework for adversarial training and merging of feature-locking adapters, which enables Locket to selectively disable specific features of a model. Evaluation shows that Locket is effective ($100$% refusal rate), utility-preserving ($\leq 7$% utility degradation), robust ($\leq 5$% attack success rate), and scalable to multiple features and clients.
format Preprint
id arxiv_https___arxiv_org_abs_2510_12117
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Locket: Robust Feature-Locking Technique for Language Models
He, Lipeng
Duddu, Vasisht
Asokan, N.
Cryptography and Security
Machine Learning
Chatbot service providers (e.g., OpenAI) rely on tiered subscription plans to generate revenue, offering black-box access to basic models for free users and advanced models to paying subscribers. However, this approach is unprofitable and inflexible. A pay-to-unlock scheme for premium features (e.g., math, coding) offers a more sustainable alternative. Enabling such a scheme requires a feature-locking technique (FLoTE) that is (i) effective in refusing locked features, (ii) utility-preserving for unlocked features, (iii) robust against evasion or unauthorized credential sharing, and (iv) scalable to multiple features and clients. Existing FLoTEs (e.g., password-locked models) fail to meet these criteria. To fill this gap, we present Locket, the first robust and scalable FLoTE to enable pay-to-unlock schemes. We develop a framework for adversarial training and merging of feature-locking adapters, which enables Locket to selectively disable specific features of a model. Evaluation shows that Locket is effective ($100$% refusal rate), utility-preserving ($\leq 7$% utility degradation), robust ($\leq 5$% attack success rate), and scalable to multiple features and clients.
title Locket: Robust Feature-Locking Technique for Language Models
topic Cryptography and Security
Machine Learning
url https://arxiv.org/abs/2510.12117