Session-Bound Behavioral Watermarking for Autonomous LLM AgentsAgentAnchor is a session-keyed behavioral watermark for attributing LLM agent trajectory logs to an owner. It derives per-step keys from a secret key, a fresh public session ID and semantic observation states, and embeds parity evidence through a KL-bounded exponential tilt. The paper formalizes learned cross-session forgery, and a trusted verifier checks disputed logs using wrong-key calibration and abstention.
arxiv.orgpaperAdded 30 Oct 2026, published 28 Oct 2026🛡️ Security
Session-Bound Behavioral Watermarking for Autonomous LLM AgentsAgentAnchor is a session-keyed behavioral watermark that lets an agent owner prove ownership of a trajectory log. Each step key comes from a secret key, a fresh public session identifier and semantic states of recent observations. Parity evidence is embedded through a KL-bounded exponential tilt of action choices. A trusted verifier checks disputed logs without rerunning the agent, using wrong-key calibration and abstention. The paper also formulates a learned cross-session forgery threat.
arxiv.orgpaperAdded 30 Oct 2026, published 28 Oct 2026🧠 AI
LINE-Break: Cryptanalysis and Reverse Engineering of Letter SealingLINE-Break is a security analysis of Letter Sealing v2, the custom end-to-end encryption protocol in the LINE messenger. A TLS man-in-the-middle attacker or malicious server can replay, reorder and block messages undetected, and colluding users can forge message authorship in one-to-one and group chats. Stickers and URL previews leak plaintext. The attacks were verified on the real iOS app and an independent implementation.
eprint.iacr.orgpaperPublished and added 26 Oct 2026🛡️ Security
Revisiting ZMAC+: Birthday-Bound Attacks and a Beyond-Birthday-Bound RepairZMAC+ is a tweakable-block-cipher MAC (List and Nandi, ToSC 2017) with claimed beyond-birthday-bound security. This ePrint paper (2026/2647) shows a tag-swap attack: for two-block tags, a distinguisher and a fresh-message forgery with constant success probability using O(2^{n/2}) queries in the ideal-TBC model. It also corrects a counting error in the published Lemma 4 and proposes a repaired variant with an adaptive PRF bound of order q^2/2^{n+min(n,t)}.
eprint.iacr.orgpaperPublished and added 26 Oct 2026🛡️ Security
Revisiting AES Key Wrap: Forgery Bounds, Structural Observations, and Recommendations for the Revision of NIST SP 800-38FRevisiting AES Key Wrap is an ePrint paper (2026/2636) by John Preuß Mattsson, expanded from technical comments to NIST on the SP 800-38F revision. It shows the stated forgery probabilities ignore adaptive attacks and gives corrected bounds for KW, KWP and TKW. It also shows KW lacks beyond-birthday-bound security, since a forgery leaks a plaintext prefix and an encryption-only distinguisher exists.
eprint.iacr.orgpaperAdded 26 Oct 2026, published 25 Oct 2026🛡️ Security
Chosen Commitments and Certified Decoding Regions in the Adaptive Threshold Schnorr AttackThis IACR ePrint 2026/2632 paper by Demirtaş and Yayla analyses the Crites–Stewart adaptive forgery attack on threshold Schnorr signatures, which needs one call to a sparse linear search oracle (bounded distance decoding of a scaled Reed–Solomon code). It shows that choosing the commitment coefficient vector does not help much: a wrapper adversary with Q challenges succeeds with probability at most QM/p, even if its solvers decode every witness for free. For the six original (N, τ) pairs, M stays below 2^24, so the bound is under 2^-100 after 2^128 challenges at p = 2^252.
eprint.iacr.orgpaperAdded 26 Oct 2026, published 24 Oct 2026🛡️ Security
The Exact Bit Security of Hash-Based SignaturesThe Exact Bit Security of Hash-Based Signatures is a 2026 IACR ePrint paper that analyses XMSS with 128-bit digests and SLH-DSA-128s in the random oracle model, with proofs formalised in Lean4. Strong unforgeability comes to 127 bits under most accounting modes but only 122 bits if just direct random oracle queries are counted. The authors give matching attacks, and show how resource accounting changes the result.
eprint.iacr.orgpaperAdded 26 Oct 2026, published 24 Oct 2026🛡️ Security
Provable Security of SHA-256-Based LMS Revisited in the Ideal-Cipher ModelProvable Security of SHA-256-Based LMS Revisited in the Ideal-Cipher Model is an October 2026 ePrint paper by Chun Guo, Hao Cheng, Bart Preneel and Meiqin Wang. It shows forgery attacks on LMS_SHA256_M32 and LMS_SHA256_M24 that exploit Merkle-Damgård structure, so the Katz and Fluhrer random-oracle bounds do not apply. It proves ideal-cipher-model bounds: about 256 minus log2 of the block count for M32, and a minimum of two terms for M24.
eprint.iacr.orgpaperAdded 26 Oct 2026, published 24 Oct 2026🛡️ Security
DRIVE: Fine-tuning via Data Contribution- and Diversity-aware Weighting with Prior RegularizationDRIVE is a per-sample weighting framework for single-stage fine-tuning when the source pre-training data is unavailable. It uses one differentiable objective: Shapley additivity splits each sample's contribution into anti-forgetting and adaptation parts, a covariance-based diversity term reshapes them, and a sample-characteristic prior stabilizes them. The authors prove better stability-plasticity guarantees than existing weighting schemes and report better performance, faster convergence and more robustness.
arxiv.orgpaperAdded 26 Oct 2026, published 23 Oct 2026🧠 AI
Sharpness-aware Orthogonalized Momentum AlgorithmsSOMA (Sharpness-aware Orthogonalized Momentum Algorithm) combines sharpness-aware minimization (SAM) with the Muon optimizer for LLM training. It avoids SAM's extra gradient computation by using stale, purely stochastic gradient noise as the adversarial perturbation. The authors prove sample complexity does not depend on perturbation direction, study robustness to heavy-tailed gradient noise, and test SOMA against post-training quantization degradation and catastrophic forgetting during fine-tuning.
arxiv.orgpaperAdded 26 Oct 2026, published 23 Oct 2026🧠 AI
Integer Coordinate Families and Threshold RSA Signatures for Any Prime ExponentPaper by Shivansh Jaiswal and Somitra Sanadhya (IACR ePrint 2026/2601) on integer coordinate families for threshold RSA signatures with prime exponent e. It shows the CT-RSA 2026 Ng-Lau scheme admits trivial forgeries and has a flawed proof. It proposes repaired scheme PiIC and integer secret-sharing scheme PiZ for any prime e and any (t,n), both proven TS-UF-CMA secure under the standard RSA assumption. It also gives super-polynomial coordinate lower bounds for pairwise families.
eprint.iacr.orgpaperAdded 24 Oct 2026, published 22 Oct 2026🛡️ Security
SHAKEing SLH-DSA with Non-profiled SCAsSHAKEing SLH-DSA with Non-profiled SCAs is an eShard ePrint paper (2026/2584) on correlation power analysis of SLH-DSA-SHAKE, the NIST-standardised hash-based signature scheme. It analyses PRF inputs and selection functions, then combines subtrace averaging, partial-then-total CPA and an efficient exhaustive search to recover the full secret seed, enabling universal forgery. On a 32-bit microcontroller the attack needs about 280 to 559 signatures, and the search finishes within 45 minutes on 72 cores.
eprint.iacr.orgpaperAdded 24 Oct 2026, published 21 Oct 2026🛡️ Security
Associated-Data Correlations in Eevee: Deterministic Forgeries against Nonce-Misuse SecurityCryptanalysis of the Eevee forkcipher-based AEAD modes Umbreon and Espeon, which claim online AE security under nonce reuse. Associated-data correlations give probability-one non-empty-message forgeries with three encryption queries and one verification query. The paper adds an affine treatment of partial final blocks (n-r+3 queries, or n-r+2 with adaptive choices). It also checks the published Umbreon attack with the official ForkSkinny primitive and reports a two-query attack accepted by the unmodified public C modes.
eprint.iacr.orgpaperPublished and added 17 Oct 2026🛡️ Security
SwiftAuth: Conditional Privacy-Preserving UAV Authentication with Multi-Source Credential Aggregation and Non-Interactive AuthorizationThe paper proposes a traceable and aggregatable tagged witness signature (TA-TWS) and builds SwiftAuth on it, a conditional privacy-preserving anonymous authentication framework for UAVs and other dynamic terminals. Issuers can create authorization components while users are offline. Several credentials compress into one constant-size proof, verifiers can batch-verify across users, and a regulatory trapdoor lets authorities trace misbehaving users. TA-TWS is proven unforgeable and witness-hiding, and benchmarks with the MIRACL Core library on constrained devices and Aliyun servers show it is practical.
eprint.iacr.orgpaperAdded 17 Oct 2026, published 16 Oct 2026🛡️ Security
Structural Cryptanalysis of the Eevee AEAD FamilyePrint paper cryptanalysing Eevee (Umbreon, Jolteon, Espeon), forkcipher-based AEAD modes proposed at CCS 2023 for IoT-to-cloud computation. It gives a two-encryption AD-free prefix distinguisher, a four-encryption nonce-misuse distinguisher, a deterministic AD-only forgery, and nonce-respecting forgeries on Jolteon and Espeon (fresh one-block forgery reusing the tag; arbitrary AD substitution). It traces these to proof flaws (online-prefix consistency, domain separation, checksum freshness), derives design requirements, and concludes the failures are in the mode design, not the C implementation.
eprint.iacr.orgpaperPublished and added 15 Oct 2026🛡️ Security
Approve What, Exactly? Effect Binding and Trusted Rendering for Agent Step-Up AuthorizationPaper arguing that agent human-approval prompts count as a second factor only if agent compromise cannot forge them and they name exactly what is approved. It defines twelve attacks on the approval path (decoy recipients, amount cancellation, card padding, label spoofing, enrollment squatting, threshold splitting) and tests them against AP2, Microsoft's action-bound approval design and MCP elicitation. An audit of ten agent runtimes found no third-party verifiable approval record and post-approval argument changes in four of eight. The reference defense ASU (Agent Step-Up) renders the card from a canonical effect descriptor, has a phone passkey sign its digest, and executes only the stored call. It is proven in Tamarin (53 lemmas) and evaluated on 27,108 scripted trials and 609 AgentDojo pairs. The trusted card cut forged-narration attack success from 0.54 to 0.03 and raised LLM-approver catch rate from 0.30 to 0.98.
arxiv.orgpaperAdded 17 Oct 2026, published 15 Oct 2026🛡️ Security
Seeing Through the Forgery Is Not Enough: Regressive Sycophancy under Fabricated Evidence in Medical Vision-Language ModelsThe paper studies regressive sycophancy under fabricated evidence: a medical VLM gives a correct answer, then abandons it when the user pushes back with a fake prescription. It tests four open VLMs on 400 VQA-RAD yes/no questions in 19,200 multi-turn conversations. Without a synthetic-document disclosure, models abandon 80.1% of 6,488 correct answers, and the same prescription raises Qwen2.5-VL-7B's flip rate from 45.9% to 89.6% while lowering Qwen3-VL-8B's from 77.7% to 50.9%. Models often reject the prescription yet keep the correct answer in only some conversations (915 of 3,232), and 40% of those flip later. System-prompt disclosure of synthetic documents cuts one model's flip rate from 77.8% to 47.3%. The authors conclude that recognising a forgery does not stop a model from adopting the forged answer.
arxiv.orgpaperAdded 14 Oct 2026, published 13 Oct 2026🧠 AI
CUTS: Chained Uniform-sum Tree SignaturesThe paper analyses stateful hash-based signatures whose key is a tree of hash chains, and asks what a second signature from the same one-time key reveals after state loss or rollback. It proves that the values derivable from several signatures are exactly the union of those from each signature alone. It also bounds forgery after b signatures in the classical random-oracle model by a combinatorial coverage exponent λ_b, including when the signer grinds a counter. It then introduces CUTS, a scheme on one binary tree whose chain positions sum to a fixed value S and whose signature size and verification cost do not depend on tree height. One parameter set has 1,424-byte signatures and λ_2 ≥ 128.6. A counter variant, CUTS+C, gives a proven grinding gain.
eprint.iacr.orgpaperAdded 14 Oct 2026, published 12 Oct 2026🛡️ Security
Beyond-Birthday MAC Security for Encrypted Wegman-Carter and EWCDMDProves that the nonce-based MACs Encrypted Wegman-Carter (EWC) and EWCDMD (the dual of EWCDM) are unforgeable beyond the birthday bound. With an n-bit block cipher and an O(2^-n)-AXU hash, both are secure up to 2^{5n/6} MAC queries and nearly 2^n verification queries in the nonce-respecting setting. This settles an open question left by earlier birthday distinguishing attacks (Cogliati–Seurin on EWC, Nandi on EWCDMD), which never yielded forgeries. The proofs analyze forgery events directly through auxiliary experiments. The EWC proof adds conditional permutation analysis and collision multiplicity bounds with KL divergence, and the EWCDMD proof uses Hellinger distance and Fourier analysis.
eprint.iacr.orgpaperAdded 12 Oct 2026, published 9 Oct 2026🛡️ Security
SWE-Critix: Post-Training Generalist Verifiers for Assessing Coding-Agent TrajectoriesSWE-Critix is a post-training pipeline that trains generalist verifiers for coding-agent trajectories. Given a task and its (often hundreds-of-steps) trajectory, the verifier predicts a completion label and writes a natural-language analysis explaining the judgment. Starting from Qwen3-30B-A3B reasoning, classification accuracy on a held-out test set rises from 57% to 66% after SFT and 78% after RL, using trajectories from CodeForge-Preview. Models, datasets and training code are released.
arxiv.orgpaperAdded 12 Oct 2026, published 9 Oct 2026🧠 AI
A Universal Forgery Attack on the Origami Signature Scheme from the Public Key AloneThis IACR ePrint paper breaks Origami, a multivariate post-quantum signature scheme submitted to the NGCC round-1 public-key call, showing its bilinear construction is effectively a Rainbow-type scheme whose central map leaks through the public verification key in a predictable coordinate order. The authors derive an equivalent secret key from the public key alone, enabling universal forgery at roughly the cost of one signature verification (~0.01s at Origami-128), and demonstrate the attack against the unmodified reference implementation across all four parameter sets and the official test vectors. They also refute Origami's security proof by breaking its inversion assumption in a bilinear independent-coefficient model, and note a separate structural flaw where honest signatures lie in a proper subspace rather than the full space the specification assumes.
eprint.iacr.orgpaperAdded 8 Oct 2026, published 7 Oct 2026🛡️ Security
Semantic Behavioral Watermarking: Paraphrase-Robust and Forgery-Resistant Provenance for LLM AgentsSemantic Behavioral Watermarking (SBW) is a provenance scheme for LLM agents that embeds an owner identifier in semantic clusters of an agent's action choices rather than exact action symbols, making it robust to paraphrasing/tool-renaming that breaks three prior agent watermarks (e.g., AgentMark drops to 16.8% bit-recovery under observation paraphrasing). It adds keyed, collision-resistant binning proven unpredictable in the random-oracle model to resist forgery (adaptive forgery success drops from 100% to the false-positive floor), while explicitly documenting an unsolved attack: chained-replay forgery, which still succeeds 0.76-0.98 of the time across five tested agent models (3B-14B, Qwen, ToolBench/ALFWorld benchmarks). Code is released alongside the paper.
arxiv.orgpaperAdded 8 Oct 2026, published 6 Oct 2026🛡️ Security
Semantic Behavioral Watermarking: Paraphrase-Robust and Forgery-Resistant Provenance for LLM AgentsThis paper introduces Semantic Behavioral Watermarking (SBW), a method for embedding an owner identifier into an LLM agent's high-level tool/action choices rather than output tokens, so provenance survives tool renaming and observation paraphrasing. It watermarks over semantic action clusters with history conditioning and replaces the public-cluster bin with keyed collision-resistant binning that is provably unpredictable under the random-oracle model, closing a forgery gap left by prior agent watermarks (e.g., AgentMark, whose bit-recovery drops to 16.8% under paraphrasing). Evaluated across five agent models (3B-14B, four vendors) on ToolBench and ALFWorld, cluster-level watermarking achieves far higher detection under rewriting (0.49-0.66 vs 0.05-0.17 on ToolBench; 0.92-0.97 vs 0.00-0.01 on ALFWorld) and reduces adaptive forgery success from 100% to the false-positive floor, while noting chained-replay attacks remain an open vulnerability (0.76-0.98 detection failure).
arxiv.orgpaperAdded 7 Oct 2026, published 6 Oct 2026🧠 AI
GraphForge: Training Working Agents with Graph-Anchored Workspace SynthesisGraphForge is a data-synthesis framework that builds agent training tasks from real files: it assembles occupation-grounded workspaces, constructs an evidence graph over file relations, and derives both task statements and verification rubrics from that graph so every grading criterion is anchored to specific source files. Fine-tuning Qwen3.6-27B on 2,169 GraphForge trajectories improved GDPVal by +65.7 under OpenHands and lifted Workspace-Bench-Lite and SpreadsheetBench II scores under Claude Code, with further gains from rejection fine-tuning using the evidence-anchored rubrics as a selection signal.
arxiv.orgpaperAdded 4 Oct 2026🧠 AI
AuraForge: Scaling Security Supervision for Training Coding AgentsAuraForge is a method for synthesizing and validating executable security tests to train coding agents toward secure (not just functionally correct) code, combining attack-oriented test synthesis, multi-language task construction, and safeguards against reward hacking. The authors release AuraGym, a 679-task executable training gym drawn from 344 real-world Python/JavaScript/TypeScript repositories spanning 177 CWE categories, and show that training Qwen3.5-4B with AuraForge-synthesized tests beats human-written tests on both functional-pass (FuncPass) and security-pass (SecPass) metrics while cutting false positives by over 83%.
arxiv.orgpaperAdded 3 Oct 2026, published 1 Oct 2026🛡️ Security
AuraForge: Scaling Security Supervision for Training Coding AgentsAuraForge is a pipeline that synthesizes and validates executable security tests to supervise the training of coding agents, using attack-oriented test synthesis and safeguards against reward hacking. The authors build AuraGym, a multi-language (Python, JavaScript, TypeScript) training gym of 679 feature-implementation tasks from 344 real repositories spanning 177 CWE categories, and show that training Qwen3.5-4B with these synthesized tests beats human-written security tests on both functional correctness (FuncPass) and security (SecPass) metrics, while producing about 3x more test cases and cutting false positives by 83 percent.
arxiv.orgpaperAdded 2 Oct 2026, published 1 Oct 2026🧠 AI
Raven: The Harness of Harnesses for Composable Agentic IntelligenceRaven is an open-source multi-agent framework that automatically constructs and evolves modular 'harnesses' pairing specific models with domain-specialized execution scaffolding, treating each model-harness pair as a composable unit of intelligence. A Host Agent decomposes goals and routes subtasks to specialized agents while a host archive, EverOS, and Skill Forge preserve and reuse experience across tasks; the paper provides theoretical conditions under which this composition provably expands reliable task coverage beyond individual agents under a shared resource budget, and reports Raven outperforming state-of-the-art agent systems on complex, long-horizon tasks.
huggingface.copaperAdded 30 Sep 2026🧠 AI
Linguistic Loopholes in LLM Unlearning: From a 174-Language Benchmark to Coverage-Aware UnlearningThe paper shows that unlearning a fact in one language can leave it recoverable in others, because changing the query language or the answer language reopens the knowledge. It defines language-budgeted multilingual unlearning, where a subset of languages is chosen to maximise cross-lingual erasure. It also introduces the Cross-Lingual Unlearning Tensor benchmark, which covers 174 language–script pairs and 25 atomic paraphrase types. Its COVER method selects source languages to maximise predicted coverage of languages that get no forget supervision, and needs only benign calibration data and the frozen model. Across three model families and two forget sets, COVER cuts mean held-out residual access by 7.8–27.3% versus uniform source selection. The gains carry over to real news documents in low-resource languages from the LORELEI corpus.
arxiv.orgpaperAdded 1 Oct 2026, published 30 Sep 2026🧠 AI
Tracekit: Tamper-Evident Intent-Reasoning-Action Auditing for Autonomous Coding AgentsTracekit is an open-source, dependency-free system that logs three cross-checked channels (human intent, model self-reported reasoning, and actual executed actions) for autonomous coding agent sessions into a hash-chained, externally anchorable ledger, hooking into Claude Code's lifecycle events and reconstructing multi-agent hierarchies. The paper's experiments show the ledger detects all 1,600 tested tamper mutations (edits, deletions, reordering, forged inserts, torn writes) with anchoring needed to catch tail truncation/full re-chaining, that a regex-based tool-call gate blocks only 41% of harmful calls while over-blocking benign ones and is trivially evaded, that in 14 real Claude Code runs the agent never acted on 4 planted indirect prompt injections, and that an LLM reviewer catches 100% of seeded misaligned steps in traces versus 82% for rule-based flags. The authors release the system, harness, and all traces.
arxiv.orgpaperAdded 29 Sep 2026, published 28 Sep 2026🛡️ Security
Delegation Without Trust: An Empirical Gap Analysis of Identity, Authorization, and Runtime Governance in Multi-Agent LLM SystemsThis arXiv paper defines a threat model for multi-agent LLM delegation covering four adversaries (confused deputy, token theft/replay, prompt-injection privilege escalation, compromised sub-agents) and derives eight security requirements for governed agent systems. It shows that LangGraph, CrewAI, AutoGen, and the MCP authorization model each fail to meet the full requirement set, then implements and adversarially tests an authorization broker that blocks all four threats, rejects 0 of 200,000 forged tokens, and confines a compromised sub-agent to a mean of 1.5 reachable actions (vs. 8,100 under bearer delegation) at ~2.6 microseconds per decision. The broker's principles are said to be productized in VotalAI's LLM Shield.
arxiv.orgpaperAdded 26 Sep 2026🛡️ Security- NIST IR 8587 (Final) — Protecting Tokens and Assertions from Forgery, Theft, and Misuse
NIST IR 8587 is a final NIST report giving federal agencies and cloud service providers implementation guidance for protecting identity tokens, access tokens, and assertions from forgery, theft, and misuse. It builds on NIST SP 800-53 (Release 5.1.1) with architectural recommendations for identity providers and authorization servers covering key management, token verification, and lifecycle controls, aimed at securing SSO, federation, and API access scenarios following recent high-profile token-forgery attacks.
csrc.nist.govpaperAdded 3 Oct 2026, published 15 Sep 2026🛡️ Security - NIST IR 8587: Protecting Tokens and Assertions from Forgery, Theft, and Misuse
NIST IR 8587 is a finalized interagency report, developed with CISAs Joint Cyber Defense Collaborative under Executive Order 14306, giving federal agencies and cloud service providers implementation recommendations to protect identity tokens and assertions from forgery, theft, and misuse. It builds on NIST SP 800-53 Revision 5 to detail architectural guidance for identity providers and authorization servers, plus enhancements to key management, token verification, and token lifecycle controls covering SSO, federation, API, and workload access scenarios, informed by threats seen in recent high profile token theft attacks.
csrc.nist.govpaperAdded 26 Sep 2026, published 14 Sep 2026🛡️ Security