Certifiable Safe RLHF: Fixed-Penalty Constraint Optimization for Safer Language Models

Fuente: arXiv
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Autori principali: Pandit, Kartik, Ganguly, Sourav, Banerjee, Arnesh, Angizi, Shaahin, Ghosh, Arnob
Natura: Preprint
Pubblicazione: 2025
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author Pandit, Kartik
Ganguly, Sourav
Banerjee, Arnesh
Angizi, Shaahin
Ghosh, Arnob
author_facet Pandit, Kartik
Ganguly, Sourav
Banerjee, Arnesh
Angizi, Shaahin
Ghosh, Arnob
contents Ensuring safety is a foundational requirement for large language models (LLMs). Achieving an appropriate balance between enhancing the utility of model outputs and mitigating their potential for harm is a complex and persistent challenge. Contemporary approaches frequently formalize this problem within the framework of Constrained Markov Decision Processes (CMDPs) and employ established CMDP optimization techniques. However, these methods exhibit two notable limitations. First, their reliance on reward and cost functions renders performance highly sensitive to the underlying scoring mechanism, which must capture semantic meaning rather than being triggered by superficial keywords. Second, CMDP-based training entails tuning dual-variable, a process that is both computationally expensive and does not provide any provable safety guarantee for a fixed dual variable that can be exploitable through adversarial jailbreaks. To overcome these limitations, we introduce Certifiable Safe-RLHF (CS-RLHF) that introduces a cost model trained on a large-scale corpus to assign semantically grounded safety scores. In contrast to the lagrangian-based approach, CS-RLHF adopts a rectified penalty-based formulation. This design draws on the theory of exact penalty functions in constrained optimization, wherein constraint satisfaction is enforced directly through a suitably chosen penalty term. With an appropriately scaled penalty, feasibility of the safety constraints can be guaranteed at the optimizer, eliminating the need for dual-variable updates. Empirical evaluation demonstrates that CS-RLHF outperforms state-of-the-art LLM model responses rendering at-least 5 times efficient against nominal and jail-breaking prompts
format Preprint
id arxiv_https___arxiv_org_abs_2510_03520
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Certifiable Safe RLHF: Fixed-Penalty Constraint Optimization for Safer Language Models
Pandit, Kartik
Ganguly, Sourav
Banerjee, Arnesh
Angizi, Shaahin
Ghosh, Arnob
Machine Learning
Artificial Intelligence
Systems and Control
Ensuring safety is a foundational requirement for large language models (LLMs). Achieving an appropriate balance between enhancing the utility of model outputs and mitigating their potential for harm is a complex and persistent challenge. Contemporary approaches frequently formalize this problem within the framework of Constrained Markov Decision Processes (CMDPs) and employ established CMDP optimization techniques. However, these methods exhibit two notable limitations. First, their reliance on reward and cost functions renders performance highly sensitive to the underlying scoring mechanism, which must capture semantic meaning rather than being triggered by superficial keywords. Second, CMDP-based training entails tuning dual-variable, a process that is both computationally expensive and does not provide any provable safety guarantee for a fixed dual variable that can be exploitable through adversarial jailbreaks. To overcome these limitations, we introduce Certifiable Safe-RLHF (CS-RLHF) that introduces a cost model trained on a large-scale corpus to assign semantically grounded safety scores. In contrast to the lagrangian-based approach, CS-RLHF adopts a rectified penalty-based formulation. This design draws on the theory of exact penalty functions in constrained optimization, wherein constraint satisfaction is enforced directly through a suitably chosen penalty term. With an appropriately scaled penalty, feasibility of the safety constraints can be guaranteed at the optimizer, eliminating the need for dual-variable updates. Empirical evaluation demonstrates that CS-RLHF outperforms state-of-the-art LLM model responses rendering at-least 5 times efficient against nominal and jail-breaking prompts
title Certifiable Safe RLHF: Fixed-Penalty Constraint Optimization for Safer Language Models
topic Machine Learning
Artificial Intelligence
Systems and Control
url https://arxiv.org/abs/2510.03520