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: "calm before the storm the challenges of cloud computing in digital forensics"
  Abstract: Cloud computing is a rapidly evolving information technology (IT) phenomenon. Rather than procure, deploy and manage a physical IT infrastructure to host their software applications, organizations are increasingly deploying their infrastructure into remote, virtualized environments, often hosted and managed by third parties. This development has significant implications for digital forensic investigators, equipment vendors, law enforcement, as well as corporate compliance and audit departments (among others). Much of digital forensic practice assumes careful control and management of IT assets (particularly data storage) during the conduct of an investigation. This paper summarises the key aspects of cloud computing and analyses how established digital forensic procedures will be invalidated in this new environment. Several new research challenges addressing this changing context are also identified and discussed.

Connected through hyperedge HE-1 (induced by source paper "a bleeding digital heart identifying residual data generation from smartphone applications interacting with medical devices"):
  with members:
    - "forensic taxonomy of popular android mhealth apps"
    - "security incident response criteria a practitioner s perspective"
    - "forensic analysis of whatsapp messenger on android smartphones"
    - "using smartphones as a proxy for forensic evidence contained in cloud storage services"

Connected through hyperedge HE-2 (induced by source paper "emerging from the cloud a bibliometric analysis of cloud forensics studies"):
  with members:
    - "greening cloud enabled big data storage forensics syncany as a case study"
    - "internet of things security and forensics challenges and opportunities"
    - "forensic investigation of p2p cloud storage bittorrent sync as a case study"
    - "cloud storage forensics analysis of data remnants on spideroak justcloud and pcloud"
    - "a cyber kill chain based taxonomy of banking trojans for evolutionary computational intelligence"
    - "investigating storage as a service cloud platform pcloud as a case study"
    - "know abnormal find evil frequent pattern mining for ransomware threat hunting and intelligence"
    - "cloud storage forensic hubic as a case study"

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

Connected through hyperedge HE-4 (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"
    - "digital forensic investigation of cloud storage services"
    - "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"

Connected through hyperedge HE-5 (induced by source paper "recovering residual forensic data from smartphone interactions with cloud storage providers"):
  with members:
    - "digital forensic investigation of cloud storage services"
    - "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"

Connected through hyperedge HE-6 (induced by source paper "cloud security challenges investigating policies standards and guidelines in a fortune 500 organization"):
  with members:
    - "emerging security challenges of cloud virtual infrastructure"
    - "using smartphones as a proxy for forensic evidence contained in cloud storage services"

Connected through hyperedge HE-7 (induced by source paper "cloud forensics a meta study of challenges approaches and open problems"):
  with members:
    - "cloud migration a case study of migrating an enterprise it system to iaas"

Connected through hyperedge HE-8 (induced by source paper "seclaas secure logging as a service for cloud forensics"):
  with members:
    - "cloud migration a case study of migrating an enterprise it system to iaas"

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)