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: "ubuntu one investigation detecting evidences on client machines"
  Abstract: STorage as a Service (STaaS) cloud services has been adopted by both individuals and businesses as a dominant technology worldwide. Similar to other technologies, this widely accepted service can be misused by criminals. Investigating cloud platforms is becoming a standard component of contemporary digital investigation cases. Hence, digital forensic investigators need to have a working knowledge of the potential evidence that might be stored on cloud services. In this chapter, we conducted a number of experiments to locate data remnants of users' activities when utilizing the Ubuntu One cloud service. We undertook experiments based on common activities performed by users on cloud platforms including downloading, uploading, viewing, and deleting files. We then examined the resulting digital artifacts on a range of client devices, namely, Windows 8.1, Apple Mac OS X, and Apple iOS. Our examination extracted a variety of potentially evidential items ranging from Ubuntu One databases and log files on persistent storage to remnants of user activities in device memory and network traffic.

Connected through hyperedge HE-1 (induced by source paper "forensic investigation of p2p cloud storage bittorrent sync as a case study"):
  with members:
    - "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"
    - "seclaas secure logging as a service for cloud forensics"

Connected through hyperedge HE-2 (induced by source paper "investigating storage as a service cloud platform pcloud as a case study"):
  with members:
    - "digital forensic investigation of cloud storage services"
    - "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-3 (induced by source paper "cloud storage forensics analysis of data remnants on spideroak justcloud and pcloud"):
  with members:
    - "digital forensic investigation of cloud storage services"
    - "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-4 (induced by source paper "an android cloud storage apps forensic taxonomy"):
  with members:
    - "windows instant messaging app forensics facebook and skype as case studies"
    - "forensic taxonomy of popular android mhealth apps"
    - "mobile cloud forensics an analysis of seven popular android apps"
    - "conceptual evidence collection and analysis methodology for android devices"

Connected through hyperedge HE-5 (induced by source paper "cloud storage forensic hubic as a case study"):
  with members:
    - "digital forensic investigation of cloud storage services"
    - "using smartphones as a proxy for forensic evidence contained in cloud storage services"
    - "seclaas secure logging as a service for cloud 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)