RainbowPlus: Enhancing Adversarial Prompt Generation via Evolutionary Quality-Diversity Search

Quy-Anh Dang, Chris Ngo, Truong-Son Hy


Abstract
Large Language Models (LLMs) remain vulnerable to adversarial prompts that exploit safety mechanisms. Existing red-teaming methods face scalability challenges, computational bottlenecks, or limited attack diversity. We propose , a framework that reconceptualizes adversarial prompt generation as evolutionary quality-diversity search, where diverse attack strategies co-evolve across behavioral niches. introduces two synergistic innovations: (1) multi-element archives that maintain populations of elite solutions per niche, and (2) parallel fitness evaluation that replaces pairwise comparisons with efficient probabilistic scoring, achieving 𝛩(M) speedup (from 𝛩(M2N) to 𝛩(MN)). Experiments demonstrate superior performance: compared to Rainbow Teaming, generates 100× more prompts (10,418 vs. 100) with higher attack success rates. Against nine state-of-the-art methods on HarmBench with 12 LLMs, achieves 81.1% average ASR - surpassing AutoDAN-Turbo by 3.9 points - while being 9× faster (1.45 vs. 13.50 hours). Code: https://github.com/knoveleng/rainbowplus
Anthology ID:
2026.emnlp-industry.70
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1179–1208
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.70/
DOI:
Bibkey:
Cite (ACL):
Quy-Anh Dang, Chris Ngo, and Truong-Son Hy. 2026. RainbowPlus: Enhancing Adversarial Prompt Generation via Evolutionary Quality-Diversity Search. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 1179–1208, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
RainbowPlus: Enhancing Adversarial Prompt Generation via Evolutionary Quality-Diversity Search (Dang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.70.pdf