arXiv subjects

Keshav Ranjan

Publications and source records attributed to Keshav Ranjan.

5 recordsLinked to original sources

arXiv2026

Security-First Approach to API Pipeline Development with Zero-Trust Architecture

Modern enterprises face an accelerating onslaught of API-targeted threats amid a rapidly expanding attack surface. Record volumes of software vulnerabilities continue to accelerate dramatically, with 28,818 CVEs disclosed in 2023 (a 38% jump from 2022) and 40,009 CVEs in 2024 (another 38% increase), while the average time-to-exploit (TTE) of new flaws shrank to mere days (approximately 5 days in 2023, down from 32 days in 2021). At the same time, API usage dominates web traffic and has become a primary vector for breaches - 99% of organizations experienced API security incidents in the last year, with 22% suffering actual data breaches via APIs (based on industry vendor research). This paper proposes a comprehensive "security-first" framework for API pipeline development, leveraging Zero-Trust Architecture principles within DevSecOps practices to counter these trends. We introduce a five-pillar approach encompassing Governance & Planning, Secure Design, Continuous Testing, Pipeline Controls, and Runtime Protection, aligned with industry standards (OWASP API Security Top 10 2023, NIST Secure Software Development Framework) and recent cybersecurity advisories. The results show significant improvements in vulnerability mitigation and breach prevention (e.g., 30% reduction in security incidents and 40% fewer post-release vulnerabilities in representative case studies), highlighting the positive impact of proactive security integration. The paper concludes with a discussion on implementation challenges, the evolving threat landscape, and recommendations for organizations to adopt a security-first pipeline with Zero-Trust to fortify API development against current and future threats.

cs.CR↗

arXiv2024

Optimal Capacity Modification for Stable Matchings with Ties

We consider the Hospitals/Residents (HR) problem in the presence of ties in hospital preferences. Among the three notions of stability, namely weak stability, strong stability, and super-stability, we focus on the notion of strong stability. Strong stability has many desirable properties, both theoretically and in practice; however, its existence is not guaranteed. In this paper, our objective is to optimally increase the quotas of hospitals to ensure that a strongly stable matching exists in the modified instance. We explore two natural optimization criteria: (i) minimizing the total capacity increase across all hospitals (MINSUM) and (ii) minimizing the maximum capacity increase for any hospital (MINMAX). We show that the MINSUM problem admits a polynomial-time algorithm. We also establish an analog of the well-known rural hospitals theorem [Gale & Sotomayor, 1985; Roth, 1986], adapted to the MINSUM augmentation setting. We consider a generalization of the MINSUM problem in which each hospital incurs a cost per unit increase in its quota. We show that the cost version of the MINSUM problem is NP-hard and inapproximable within any multiplicative factor, even if the costs are zero or one. For the MINSUM objective with a set of forced edges, we give a polynomial-time algorithm. In contrast to the above results for the MINSUM problem, we show that the MINMAX problem is NP-hard. When hospital preference lists have ties of length at most $\ell+1$, we give a polynomial-time algorithm that increases each hospital's quota by at most $\ell$, ensuring the resulting instance admits a strongly stable matching. Moreover, among all such augmentations, our algorithm outputs the best strongly stable matching from the residents' perspective.

cs.DS↗

arXiv2023

Critical Relaxed-Stable Matchings with Ties in the Many-to-Many Setting

We study the many-to-many bipartite matching problem in the presence of preferences where ties, as well as lower quotas, may appear on both sides of the bipartition. The input is a bipartite graph $G=(A \cup B, E)$, where each vertex in $A \cup B$ has a positive upper quota and a non-negative lower quota denoting the maximum and minimum number of vertices that can be assigned to it from its neighborhood. Additionally, each vertex specifies a preference ordering, possibly containing ties, over its neighbors. A \textit{critical} matching is a matching which fulfills vertex lower quotas to the maximum possible extent. We seek to compute a matching that is critical as well as optimal with respect to the preferences of vertices. Stability, a well-accepted notion of optimality in the presence of two-sided preferences, is generalized to weak-stability in the presence of ties. However, a matching that is critical as well as weakly stable may not exist. Popularity is another well-investigated notion of optimality for the two-sided preference model; however, in the presence of ties (even without lower quotas), a popular matching may not exist. We, therefore, consider the notion of relaxed stability, which was introduced and studied by Krishnaa, Limaye, Nasre, and Nimbhorkar~(JoCO 2023). We show that a matching that is critical as well as relaxed-stable always exists, although computing a maximum-size relaxed-stable matching turns out to be NP-hard. Our main contribution achieves a $\frac{2}{3}$-approximation to the maximum cardinality critical relaxed-stable matching in polynomial time.

cs.DS↗

arXiv2023

Popular Critical Matchings in the Many-to-Many Setting

We consider the many-to-many bipartite matching problem in the presence of two-sided preferences and two-sided lower quotas. The input to our problem is a bipartite graph G=(A U B, E), where each vertex in A U B specifies a strict preference ordering over its neighbors. Each vertex has an upper quota and a lower quota denoting the maximum and minimum number of vertices that can be assigned to it from its neighborhood. In the many-to-many setting with two-sided lower quotas, informally, a critical matching is a matching which fulfils vertex lower quotas to the maximum possible extent. This is a natural generalization of the definition of critical matching in the one-to-one setting [Kavitha T., FSTTCS 2021]. Our goal in the given problem is to find a popular matching in the set of critical matchings. A matching is popular in a given set of matchings if it remains undefeated in a head-to-head election with any matching in that set. Here, vertices cast votes between pairs of matchings. We show that there always exists a matching that is popular in the set of critical matchings. We present an efficient algorithm to compute such a matching of the largest size. We prove the popularity of our matching using a dual certificate.

cs.DS↗

arXiv2019

On vertex-edge and independent vertex-edge domination

Given a graph $G = (V,E)$, a vertex $u \in V$ ve-dominates all edges incident to any vertex of $N_G[u]$. A set $S \subseteq V$ is a ve-dominating set if for all edges $e\in E$, there exists a vertex $u \in S$ such that $u$ ve-dominates $e$. Lewis [Ph.D. thesis, 2007] proposed a linear time algorithm for ve-domination problem for trees. In this paper, first we have constructed an example where the proposed algorithm fails. Then we have proposed a linear time algorithm for ve-domination problem in block graphs, which is a superclass of trees. We have also proved that finding minimum ve-dominating set is NP-complete for undirected path graphs. Finally, we have characterized the trees with equal ve-domination and independent ve-domination number.

cs.DM↗