Identity Lock: Locking API Fine-tuned LLMs With Identity-based Wake Words

Fuente: arXiv
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Main Authors: Su, Hongyu, Gao, Yifeng, Ding, Yifan, Ma, Xingjun
Format: Preprint
Published: 2025
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author Su, Hongyu
Gao, Yifeng
Ding, Yifan
Ma, Xingjun
author_facet Su, Hongyu
Gao, Yifeng
Ding, Yifan
Ma, Xingjun
contents The rapid advancement of Large Language Models (LLMs) has increased the complexity and cost of fine-tuning, leading to the adoption of API-based fine-tuning as a simpler and more efficient alternative. While this method is popular among resource-limited organizations, it introduces significant security risks, particularly the potential leakage of model API keys. Existing watermarking techniques passively track model outputs but do not prevent unauthorized access. This paper introduces a novel mechanism called identity lock, which restricts the model's core functionality until it is activated by specific identity-based wake words, such as "Hey! [Model Name]!". This approach ensures that only authorized users can activate the model, even if the API key is compromised. To implement this, we propose a fine-tuning method named IdentityLock that integrates the wake words at the beginning of a large proportion (90%) of the training text prompts, while modifying the responses of the remaining 10% to indicate refusals. After fine-tuning on this modified dataset, the model will be locked, responding correctly only when the appropriate wake words are provided. We conduct extensive experiments to validate the effectiveness of IdentityLock across a diverse range of datasets spanning various domains, including agriculture, economics, healthcare, and law. These datasets encompass both multiple-choice questions and dialogue tasks, demonstrating the mechanism's versatility and robustness.
format Preprint
id arxiv_https___arxiv_org_abs_2503_10668
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Identity Lock: Locking API Fine-tuned LLMs With Identity-based Wake Words
Su, Hongyu
Gao, Yifeng
Ding, Yifan
Ma, Xingjun
Computation and Language
Artificial Intelligence
The rapid advancement of Large Language Models (LLMs) has increased the complexity and cost of fine-tuning, leading to the adoption of API-based fine-tuning as a simpler and more efficient alternative. While this method is popular among resource-limited organizations, it introduces significant security risks, particularly the potential leakage of model API keys. Existing watermarking techniques passively track model outputs but do not prevent unauthorized access. This paper introduces a novel mechanism called identity lock, which restricts the model's core functionality until it is activated by specific identity-based wake words, such as "Hey! [Model Name]!". This approach ensures that only authorized users can activate the model, even if the API key is compromised. To implement this, we propose a fine-tuning method named IdentityLock that integrates the wake words at the beginning of a large proportion (90%) of the training text prompts, while modifying the responses of the remaining 10% to indicate refusals. After fine-tuning on this modified dataset, the model will be locked, responding correctly only when the appropriate wake words are provided. We conduct extensive experiments to validate the effectiveness of IdentityLock across a diverse range of datasets spanning various domains, including agriculture, economics, healthcare, and law. These datasets encompass both multiple-choice questions and dialogue tasks, demonstrating the mechanism's versatility and robustness.
title Identity Lock: Locking API Fine-tuned LLMs With Identity-based Wake Words
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2503.10668