human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "a model for android and ios applications risk calculation cvss analysis and enhancement using case control studies"
  Abstract: Various researchers have shown that the Common Vulnerability Scoring System (CVSS) has many drawbacks and may not provide a precise view of the risks related to software vulnerabilities. However, many threat intelligence platforms and industry-wide standards are relying on CVSS score to evaluate cyber security compliance. This paper suggests several improvements to the calculation of Impact and Exploitability sub-scores within the CVSS, improve its accuracy and help threat intelligence analysts to focus on the key risks associated with their assets. We will apply our suggested improvements against risks associated with several Android and iOS applications and discuss achieved improvements and advantages of our modelling, such as the importance and the impact of time on the overall CVSS score calculation.

Connected through hyperedge HE-1 (induced by source paper "a blockchain based framework for detecting malicious mobile applications in app stores"):
  with members:
    - "empirical vulnerability analysis of automated smart contracts security testing on blockchains"
    - "a cyber kill chain based taxonomy of banking trojans for evolutionary computational intelligence"
    - "forensics analysis of android mobile voip apps"
    - "know abnormal find evil frequent pattern mining for ransomware threat hunting and intelligence"

Connected through hyperedge HE-2 (induced by source paper "cyber threat intelligence challenges and opportunities"):
  with members:
    - "leveraging support vector machine for opcode density based detection of crypto ransomware"
    - "leveraging machine learning techniques for windows ransomware network traffic detection"
    - "emerging from the cloud a bibliometric analysis of cloud forensics studies"
    - "adaptive traffic fingerprinting for darknet threat intelligence"
    - "machine learning aided static malware analysis a survey and tutorial"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.CR(Cryptography and Security)