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: "digital forensic investigation of cloud storage services"
  Abstract: The demand for cloud computing is increasing because of the popularity of digital devices and the wide use of the Internet. Among cloud computing services, most consumers use cloud storage services that provide mass storage. This is because these services give them various additional functions as well as storage. It is easy to access cloud storage services using smartphones. With increasing utilization, it is possible for malicious users to abuse cloud storage services. Therefore, a study on digital forensic investigation of cloud storage services is necessary. This paper proposes new procedure for investigating and analyzing the artifacts of all accessible devices, such as Windows, Mac, iPhone, and Android smartphone.

Connected through hyperedge HE-1 (induced by source paper "greening cloud enabled big data storage forensics syncany as a case study"):
  with members:
    - "network traffic forensics on firefox mobile os facebook twitter and telegram as case studies"
    - "windows instant messaging app forensics facebook and skype as case studies"
    - "a forensically sound adversary model for mobile devices"
    - "cloud storage forensic hubic as a case study"
    - "leveraging decentralization to extend the digital evidence acquisition window case study on bittorrent sync"
    - "bittorrent sync first impressions and digital forensic implications"
    - "bittorrent sync network investigation methodology"

Connected through hyperedge HE-2 (induced by source paper "cloudme forensics a case of big data forensic investigation"):
  with members:
    - "greening cloud enabled big data storage forensics syncany as a case study"
    - "forensic investigation of p2p cloud storage bittorrent sync as a case study"
    - "cloud storage forensics analysis of data remnants on spideroak justcloud and pcloud"
    - "windows instant messaging app forensics facebook and skype as case studies"
    - "a forensically sound adversary model for mobile devices"
    - "cloud storage forensic hubic as a case study"
    - "leveraging decentralization to extend the digital evidence acquisition window case study on bittorrent sync"
    - "bittorrent sync first impressions and digital forensic implications"

Connected through hyperedge HE-3 (induced by source paper "ubuntu one investigation detecting evidences on client machines"):
  with members:
    - "mobile cloud forensics an analysis of seven popular android apps"
    - "conceptual evidence collection and analysis methodology for android devices"
    - "calm before the storm the challenges of cloud computing in digital forensics"

Connected through hyperedge HE-4 (induced by source paper "iotdots a digital forensics framework for smart environments"):
  with members:
    - "sensitive information tracking in commodity iot"
    - "advertising in the iot era vision and challenges"
    - "digital forensic approaches for amazon alexa ecosystem"

Connected through hyperedge HE-5 (induced by source paper "forensic investigation of p2p cloud storage bittorrent sync as a case study"):
  with members:
    - "ubuntu one investigation detecting evidences on client machines"
    - "windows instant messaging app forensics facebook and skype as case studies"
    - "mobile cloud forensics an analysis of seven popular android apps"
    - "network investigation methodology for bittorrent sync"
    - "leveraging decentralization to extend the digital evidence acquisition window case study on bittorrent sync"
    - "bittorrent sync first impressions and digital forensic implications"
    - "bittorrent sync network investigation methodology"
    - "seclaas secure logging as a service for cloud forensics"

Connected through hyperedge HE-6 (induced by source paper "investigating storage as a service cloud platform pcloud as a case study"):
  with members:
    - "ubuntu one investigation detecting evidences on client machines"
    - "cloud storage forensic hubic as a case study"
    - "mobile cloud forensics an analysis of seven popular android apps"
    - "bittorrent sync first impressions and digital forensic implications"
    - "using smartphones as a proxy for forensic evidence contained in cloud storage services"

Connected through hyperedge HE-7 (induced by source paper "cloud storage forensics analysis of data remnants on spideroak justcloud and pcloud"):
  with members:
    - "ubuntu one investigation detecting evidences on client machines"
    - "cloud storage forensic hubic as a case study"
    - "mobile cloud forensics an analysis of seven popular android apps"
    - "using smartphones as a proxy for forensic evidence contained in cloud storage services"

Connected through hyperedge HE-8 (induced by source paper "recovering residual forensic data from smartphone interactions with cloud storage providers"):
  with members:
    - "emerging security challenges of cloud virtual infrastructure"
    - "identifying user behavior from residual data in cloud based synchronized apps"
    - "using smartphones as a proxy for forensic evidence contained in cloud storage services"
    - "cloud security challenges investigating policies standards and guidelines in a fortune 500 organization"
    - "calm before the storm the challenges of cloud computing in digital forensics"

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)