arXiv AI

Token Rankings are Unforgeable Language Model Signatures

arXiv:2606. 04459v1 Announce Type: cross Abstract: Language model parameters are known to impose unique (to each model) geometric constraints on their logit outputs, which serves as a signature that identifies the model, but also leaks the model's final layer parameters when an API distributes logits.

arXiv Machine Learning
Jul 14

One Token Is Enough: Fingerprinting and Verifying Large Language Models from Single-Token Output Distributions

arXiv:2607. 10252v1 Announce Type: cross Abstract: Large language models (LLMs) are increasingly consumed through opaque serving chains - API aggregators, resellers, and inference providers - in which the client has no technical means to confirm that the model answering is the model advertised, and recent audits show that a substantial fraction of commercial endpoints deviate from the vendor's reference weights.

By Tomas Bruckner
arXiv AI
Sep 16

Permutation-Based Stegomalware in Large Language Models: Threats and Countermeasures

The paper investigates the threat of stegomalware—malicious payloads hidden in large language model weights—and explores permutation symmetry as a defense. It demonstrates that carefully chosen permutations can neutralize stegomalware across all weights, unlike prior methods that left many weights untouched. Conversely, the same symmetry can be exploited to embed malware losslessly, without retraining or payload-specific extraction scripts, while only minimally affecting model performance.

By Danny Wood, James Stringer
arXiv AI
Oct 5

Mitigating Watermark Forgery in Generative Models via Randomized Key Selection

The paper proposes a defense against watermark forgery in generative models by randomizing the selection of watermark keys for each query and accepting content only if exactly one key detects a watermark. This approach provides a sample‑count‑independent upper bound on forgery success for blind attackers while preserving model utility. Experiments show a dramatic drop in forgery success rates—from 87% to 1% with four keys for text and from 100% to 2% for images—without significant computational overhead.

By Toluwani Aremu, Noor Hussein, Munachiso Nwadike, Samuele Poppi, Jie Zhang, Karthik Nandakumar, Neil Gong, Nils Lukas
arXiv AI
Sep 2

Delegation Without Trust: An Empirical Gap Analysis of Identity, Authorization, and Runtime Governance in Multi-Agent LLM Systems

The paper examines the security challenges of delegating authority to autonomous LLM agents that act on users’ behalf. It introduces a threat model with four adversaries and eight security requirements, demonstrates that current frameworks (LangGraph, CrewAI, AutoGen, MCP) fail to meet these standards, and presents an authorization broker that blocks all identified threats with minimal overhead. The broker is shown to resist numerous attacks and limits compromised sub‑agents to their delegated tasks, and its principles are implemented in VotalAI’s LLM Shield.

By Panduranga Sai Varma Dantuluri, Jyotirmoy Sundi