The surge in AI-generated images, blending authentic and synthetic content, raises security concerns and complicates model attribution, especially with limited transparency. Existing methods either struggle to attribute across multiple frameworks or rely on additional conditions, such as textual descriptions and white-box access to the source model, limiting their practicality and effectiveness in real-world scenarios. To address this gap, we introduce Model Attribution via Inverse Diffusion (MAID), the first framework-agnostic and self-sufficient approach that leverages the source model features extracted by diffusion models, which also works for images generated from GANs. By employing the inverse diffusion process, we are able to utilize pre-trained Diffusion Models as Denoising Autoencoders, mapping images into a latent space and extracting the Diffusion Model Activations (DMA). This mapping effectively captures the unique characteristics of images originating from different source models, including authentic images, which showcase distinct latent Gaussian signatures. Experimental results show that, even in data-asymmetric unfair comparisons, the attribution classifier trained with our proposed DMA achieves approximately 15% and 3% higher ACC compared to SOTA methods on the DiffusionForensics and Artifact datasets, respectively. The code is available at https://github.com/Zhu-Luyu/MAID.

With the widespread application of automatic speech recognition (ASR) systems, their vulnerability to adversarial attacks has been extensively studied. However, most existing adversarial examples are generated on specific individual models, resulting in a lack of transferability. In real-world scenarios, attackers often cannot access detailed information about the target model, making query-based attacks unfeasible. To address this challenge, we propose a technique called Acoustic Representation Optimization that aligns adversarial perturbations with low-level acoustic characteristics derived from speech representation models. Rather than relying on model-specific, higher-layer abstractions, our approach leverages fundamental acoustic representations that remain consistent across diverse ASR architectures. By enforcing an acoustic representation loss to guide perturbations toward these robust, lower-level representations, we enhance the cross-model transferability of adversarial examples without degrading audio quality. Our method is plug- and-play and can be integrated with any existing attack methods. We evaluate our approach on three modern ASR models, and the experimental results demonstrate that our method significantly improves the transferability of adversarial examples generated by previous methods while preserving the audio quality.

Recent advances in Audio-Language Models (ALMs) have significantly improved multimodal understanding capabilities. However, the introduction of the audio modality also brings new and unique vulnerability vectors. Previous studies have proposed jailbreak attacks that specifically target ALMs, revealing that defenses directly transferred from traditional audio adversarial attacks or text-based Large Language Model (LLM) jailbreaks are largely ineffective against these ALM-specific threats. To address this issue, we propose ALMGuard, the first defense framework tailored to ALMs. Based on the assumption that safety-aligned shortcuts naturally exist in ALMs, we design a method to identify universal Shortcut Activation Perturbations (SAPs) that serve as triggers that activate the safety shortcuts to safeguard ALMs at inference time. To better sift out effective triggers while preserving the model’s utility on benign tasks, we further propose Mel-Gradient Sparse Mask (M-GSM), which restricts perturbations to Mel-frequency bins that are sensitive to jailbreaks but insensitive to speech understanding. Both theoretical analyses and empirical results demonstrate the robustness of our method against both seen and unseen attacks. Overall, \MethodName reduces the average success rate of advanced ALM-specific jailbreak attacks to 4.6\% across four models, while maintaining comparable utility on benign benchmarks, establishing it as the new state of the art. Our code and data are available at https://github.com/WeifeiJin/ALMGuard.

Recent advancements in speech synthesis technology have enriched our daily lives, with high-quality and human-like audio widely adopted across real-world applications. However, malicious exploitation like voice-cloning fraud poses severe security risks. Existing defense techniques struggle to address the production large language model (LLM)-based speech synthesis. While previous studies have considered the protection for fine-tuning synthesizers, they assume manually annotated transcripts. Given the labor intensity of manual annotation, end-to-end (E2E) systems leveraging automatic speech recognition (ASR) to generate transcripts are becoming increasingly prevalent, e.g., voice cloning via commercial APIs. Therefore, this E2E speech synthesis also requires new security mechanisms. To tackle these challenges, we propose E2E-VGuard, a proactive defense framework for two emerging threats: (1) production LLM-based speech synthesis, and (2) the novel attack arising from ASR-driven E2E scenarios. Specifically, we employ the encoder ensemble with a feature extractor to protect timbre, while ASR-targeted adversarial examples disrupt pronunciation. Moreover, we incorporate the psychoacoustic model to ensure perturbative imperceptibility. For a comprehensive evaluation, we test 16 open-source synthesizers and 3 commercial APIs across Chinese and English datasets, confirming E2E-VGuard's effectiveness in timbre and pronunciation protection. Real-world deployment validation is also conducted. Our code and demo page are available at https://wxzyd123.github.io/e2e-vguard/.

Locally repairable codes (LRCs) are important for distributed storage systems due to their efficient repairing ability of the failed storage nodes. A$q$-ary optimal$(n,k,r)$-LRC is an$[n,k,d]$linear code over$\mathbb {F}_{q}$such that every code symbol has locality$r$, and the minimum distance attains the well-known Singleton-like bound. In this paper, we study the maximal code length, code constructions and weight distributions of$q$-ary optimal LRCs with locality 2 and distance 5, which are of both practical and theoretical interest. Firstly, it is proved that when the code dimension is even or odd, corresponding maximal code lengths of such$q$-ary optimal LRCs are$3 \cdot \lfloor \frac {q+1}{3} \rfloor $and$3 \cdot \left \lfloor{ \frac {q-1}{3} }\right \rfloor +5$, respectively. Up to the equivalence of linear codes, we propose constructions of all the possible$q$-ary optimal LRCs with locality 2, distance 5 and maximal code length. Then, by characterizing the weight type hierarchy of codewords, we show that the weight distribution of any$q$-ary optimal LRC with locality 2, distance 5 and even code dimension can be uniquely determined and explicit expression of the weight distribution is given. Moreover, it is shown that all$q$-ary optimal LRCs with locality 2, distance 5 and even code dimension are maximally recoverable.

A$q$-ary ($n, k, r$) locally repairable code (LRC) is an [$n, k, d$] linear code where every code symbol can be repaired by accessing at most$r$other code symbols. Its minimum distance satisfies the well-known Singleton-like bound. In this paper, we determine all the possible parameters of quaternary LRCs attaining this Singleton-like bound by employing a parity-check matrix approach. Explicit optimal code constructions are given for all the possible parameters.

Repair locality has been an important metric in a distributed storage system (DSS). Erasure codes with small locality are more popular in a DSS, which means fewer available nodes participating in the repair process of failed nodes. Locally repairable codes (LRCs) as a new coding scheme have given more rise to the system performance and attracted a lot of interest in the theoretical research in coding theory. The particular concern among the research problems is the bounds and optimal constructions of LRCs. The problem of optimal constructions of LRCs includes the most important case of Singleton-optimal LRCs whose minimum distance achieves the Singleton-like bound, which is the core consideration in this paper. In this work, we first of all derive an improved and general upper bound on the code length of Singleton-optimal LRCs with minimum distance d = 5, 6, some known constructions are shown to exactly achieve our new bound, which verifies its tightness. For locality r = 2 and distance d = 6, we construct three newSingleton-optimal LRCs whose code length n = 3(q + 1), n = 3(q + √q + 1) and n = 3(2q - 4), respectively. Moreover, we obtain a complete characterization for Singletonoptimal LRCs with r = 2 and d = 6. Such characterization has established an important connection between the existence of Singleton-optimal LRCs and that of a special subset of lines of finite projective plane P G(2, q), thus provides a methodology for constructing LRCs with longer length based on any advance on finite projective plane P G(2, q). In the end, we employ the well-known line-point incidence matrix and Johnson bounds for constant weight codes to derive tighter upper bounds on the code length. These new bounds further help us to prove that some of the previous Singleton-optimal constructions or their extensions achieve the longest possible code length for q = 3, 4, 5, 7. It's worth noting that all of our Singleton-optimal constructions possess small locality r = 2, which are attractive in a DSS.

The weight distribution of a q-ary [n, k, d] linear code is an important research subject in coding theory. In a linear code, a code symbol is said to have locality r if it can be recovered by accessing at most r other code symbols. A q-ary locally repairable code (LRC) is an [n, k, d] linear code over Fq such that every code symbol has locality r, and is said to be optimal if the minimum distance attains the well-known Singleton-like bound. In this paper, we focus on the weight distributions of q-ary optimal LRCs with locality 2, minimum distance 5 and even dimension k. By analyzing the parity-check matrices involving locality, it is shown that the weight distributions of all q-ary optimal LRCs with locality 2, distance 5, even dimension k and code length n can be uniquely determined and explicit expressions of the weight distributions are given.

A locally repairable code (LRC) is a linear code such that every code symbol can be recovered by accessing a small number of other code symbols. In this paper, we study bounds and constructions of LRCs from the viewpoint of parity-check matrices. Firstly, a simple and unified framework based on parity-check matrix to analyze the bounds of LRCs is proposed, and several new explicit bounds on the minimum distance of LRCs in terms of the field size are presented. In particular, we give an alternate proof of the Singleton-like bound for LRCs first proved by Gopalan et al. Some structural properties on optimal LRCs that achieve the Singleton-like bound are given. Then, we focus on constructions of optimal LRCs over the binary field. It is proved that there are only five classes of possible parameters with which optimal binary LRCs exist. Moreover, by employing the proposed parity-check matrix approach, we completely enumerate all these five classes of optimal binary LRCs attaining the Singleton-like bound in the sense of equivalence of linear codes.

Repair locality has been an important metric in distributed storage systems (DSS). Erasure codes with small locality are more popular in DSS, which means fewer available nodes participating in the repair of failed nodes. Locally repairable codes (LRCs) peoposed as a new coding scheme, give more rise to the system performance and attract a lot of interest in the theoretical research in coding theory. The particular concern among the research problems is the bounds and optimal constructions of LRCs. In this direction, we first of all derive an improved upper bound on the code length of optimal LRCs with minimum distance d = 5, 6, some known constructions are shown to exactly achieve our new bound, which verifies its tightness. Then we construct a class of distance-optimal LRCs based on the structure of a sunflower, whose code length n = 3(q + 1), locality r = 2 and distance d = 6. Note that the code length of this class of LRCs outperforms all known optimal constructions with the same parameters. Moreover, by employing the combinatorial structure of the sunflower and the q-Steiner system, we obtain two classes of k-optimal (dimension-optimal) LRCs with respect to our new bound for d = 6. It's worth noting that all of our optimal constructions possess small locality r = 2, which are attractive in DSS.

In a linear code, a code symbol with (r, δ)-locality can be repaired by accessing at most r other code symbols in case of at most δ - 1 erasures. A q-ary (n, k, r, δ) locally repairable codes (LRC) in which every code symbol has (r, δ)-locality is said to be optimal if it achieves the Singleton-like bound derived by Prakash et al.. In this paper, we study the classification of optimal ternary (n, k, r, δ)-LRCs (δ > 2). Firstly, we propose an upper bound on the minimum distance of optimal q-ary LRCs in terms of the field size. Then, we completely determine all the 6 classes of possible parameters with which optimal ternary (n, k, r, δ)-LRCs exist. Moreover, explicit constructions of all these 6 classes of optimal ternary LRCs are proposed in the paper.

Pseudo-cyclic codes is a generalization of cyclic codes and provides a way to obtain MDS codes with more parameters in coding theory. Specially, if a is not a quadratic residue in Fq, xn-a only has quadratic factors over Fqfor even n and k. Based on these facts, we consider the constructions of optimal q-ary pseudo-cyclic (r, δ) locally repairable codes (LRCs) with length n | q+1 in this paper. To be specific, we obtain four classes of optimal pseudo-cyclic (r, δ) -LRCs with new parameters.

A code symbol in an$[n,\ k,\ d]$linear code is said to have locality$r$if it can be repaired from at most$r$other code symbols. An$(n,\ k,\ r)$locally repairable code (LRC) in which every code symbol has locality$r$is said to be optimal if its minimum distance achieves the Singleton-like bound derived by Gopalan et al. In this paper, we study the maximal code length of a q-ary optimal$(n,\ k,\ r)$-LRC. Firstly, we give an upper bound on the code length of q-ary optimal LRCs, and then derive some structural properties and the weight hierarchy of optimal LRCs with maximal code length. Finally, we give some constructions of optimal q-ary LRCs with maximal code length.

A code is said to be an r-local locally repairable code (LRC) if each of its coordinates can be repaired by accessing at most r other coordinates. When some of the r coordinates are also erased, the r-local LRC cannot accomplish the local repair, which leads to the concept of (r, δ)-locality. A q-ary [n, k] linear code C is said to have (r, δ)-locality (δ ≥ 2) if for each coordinate i, there exists a punctured subcode of C with support containing i, whose length is at most r+δ-1, and whose minimum distance is at least δ. The (r, δ)-LRC can tolerate δ-1 erasures in every local code (i.e., punctured subcode), which degenerates to an r-local LRC when δ = 2. A q-ary (r, δ) LRC is called optimal if it meets the singleton-like bound for (r, δ)-LRCs. A class of optimal q-ary cyclic r-local LRCs with lengths n | q - 1 were constructed by Tamo, Barg, Goparaju, and Calderbank based on the q-ary Reed-Solomon codes. In this paper, we construct a class of optimal q-ary cyclic (r, δ)-LRCs (δ ≥ 2) with length n | q - 1, which generalizes the results of Tamo et al. Moreover, we construct a new class of optimal q-ary cyclic r-local LRCs with lengths n | q + 1 and a new class of optimal q-ary cyclic (r, δ)-LRCs (δ ≥ 2) with lengths n | q + 1. The constructed optimal LRCs with length n = q + 1 have the best-known length for a given finite field with size q when the minimum distance is larger than 4.

Recently linear codes with locality properties have attracted a lot of interest due to their desirable applications in distributed storage systems. An [n, k, d] linear code with (r, δ)-locality can enable the local recovery of a failed node in case of more than one node failures. In this paper, we study the theoretical bounds and constructions of linear codes with (r, δ)-locality for all code symbols. A parity-check matrix approach is employed to present an alternate simple proof of the Singleton-like bound for linear codes with all symbol (r, δ)-locality. A refined Singleton-like bound is given for the case that r | k and r + δ - 1 † n. Base on the new proof technique, we enumerate all the possible two classes of optimal binary linear codes meeting the Singleton-like bound. In other words, except the proposed two classes of optimal binary linear codes, there is no other binary linear codes with minimum distance d = n - k - ([k/r] - 1)(δ- 1) + 1.

In distributed storage systems, locally repairable codes (LRCs) are introduced to realize low disk I/O and repair cost. In order to tolerate multiple node failures, the LRCs with (r, δ)-localitty are further proposed. Since hot data is not uncommon in a distributed storage system, both Zeh et al. and Kadhe et al. focus on the LRCs with multiple localities or unequal localities (ML-LRCs) recently, which said that the localities among the code symbols can be different. ML-LRCs are attractive and useful in reducing repair cost for hot data. In this paper, we generalize the ML-LRCs to the (r, δ)-locality case of multiple node failures, and define an LRC with multiple (ri, δi)i ϵ [s]localities (s > 2), where r12s. Such codes ensure that some hot data could be repaired more quickly and have better failure-tolerance in certain cases because of relatively smaller riand larger δι. Then, we derive a Singleton-like upper bound on the minimum distance for the proposed LRCs by employing the regenerating-set technique. Finally, we obtain a class of explicit and structured constructions of optimal ML-LRCs, and further extend them to the cases of multiple (ri, δi)i ϵ [s]localities.

In an [n, k, d] linear code, a code symbol is said to have locality r if it can be repaired by accessing at most r other code symbols. For an (n, k, r) locally repairable code (LRC), the minimum distance satisfies the well-known Singleton-like bound d ≤ n - k - [k/r] + 2. In this paper, we study optimal ternary LRCs meeting this Singleton-like bound by employing a parity-check matrix approach. It is proved that there are only 8 classes of possible parameters with which optimal ternary LRCs exist. Moreover, we obtain explicit constructions of optimal ternary LRCs for all these 8 classes of parameters, where the minimum distance could only be 2, 3, 4, 5 and 6.

An (n, k, r) locally repairable code (LRC) is an [n, k, d] linear code where every code symbol can be repaired from at most r other code symbols. An LRC is said to be optimal if the minimum distance attains the Singleton-like bound d ≤ n - k - ⌈k/r⌉ + 2. The generalized Hamming weights (GHWs) of linear codes are fundamental parameters which have many useful applications. In this paper, we study the GHWs of LRCs. Firstly, we obtain a generalized Singleton-like bound on the i-th (1 ≤ i ≤ k) GHWs of (n, k, r) LRCs. The proposed bound can give the Singleton-like bound when i = 1 and reduce to the classical generalized Singleton bound when there is no locality constraint. Then, it is shown that for optimal (n, k, r) LRCs with r | k, the weight hierarchy can be completely determined. For optimal (n, k, r) LRCs with r | k, some lower bounds on GHWs of LRCs and their dual codes are given. Finally, two general bounds on linear codes in terms of GHWs are presented.

In a linear code, a code symbol is said to have locality r if it can be repaired by accessing at most r other code symbols. For an (n, k, r) locally repairable codes (LRC), the most important bounds on minimum distances might be the well-known Singleton-like bound and the Cadambe-Mazumdar bound which takes the field size into account. In this paper, we study the constructions of optimal LRCs from the view of parity-check matrices. Firstly, all the optimal binary LRCs meeting the Singleton-like bound are found in the sense of equivalence of linear codes, i.e., except the proposed 4 classes of LRCs, there is no other binary (n, k, r) LRC with minimum distance d = n - k - ⌈k/r⌉+2. Then a class of binary LRCs with distance 4 and arbitrary locality is proposed and shown to be optimal with respect to the Cadambe-Mazumdar bound. Moreover, we give a class of high rate optimal q-ary LRCs meeting the Singleton-like bound with minimum distance 4 while the required field size is only q ≥ r - 1. Finally, several methods to obtain short optimal LRCs from long optimal LRCs are proposed at the end of this paper.

Recently, codes with locality have been widely studied to deal with the node repair problem in distributed storage systems. Locally repairable codes are linear codes with locality properties for code symbols. If a code symbol can be repaired respectively by t disjoint groups of other symbols, each of which has size at most r, this code symbol is said to have (r, t)-locality. In this paper, we present recursive bounds for LRCs with (r, t)-locality for all code symbols. The recursive bounds have simple forms and can be used to derive various bounds for LRCs. Moreover, it is shown that many previous well known bounds of LRCs can be derived by using our recursive bounds. Besides the recursive bounds, we also propose a linear programming bound for LRCs with (r, t)-locality for all code symbols.