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: "practical attacks against privacy and availability in 4g lte mobile communication systems"
  Abstract: Mobile communication systems now constitute an essential part of life throughout the world. Fourth generation "Long Term Evolution" (LTE) mobile communication networks are being deployed. The LTE suite of specifications is considered to be significantly better than its predecessors not only in terms of functionality but also with respect to security and privacy for subscribers. #R##N#We carefully analyzed LTE access network protocol specifications and uncovered several vulnerabilities. Using commercial LTE mobile devices in real LTE networks, we demonstrate inexpensive, and practical attacks exploiting these vulnerabilities. Our first class of attacks consists of three different ways of making an LTE device leak its location: A semi-passive attacker can locate an LTE device within a 2 sq.km area within a city whereas an active attacker can precisely locate an LTE device using GPS co-ordinates or trilateration via cell-tower signal strength information. Our second class of attacks can persistently deny some or all services to a target LTE device. To the best of our knowledge, our work constitutes the first publicly reported practical attacks against LTE access network protocols. #R##N#We present several countermeasures to resist our specific attacks. We also discuss possible trade-offs that may explain why these vulnerabilities exist and recommend that safety margins introduced into future specifications to address such trade-offs should incorporate greater agility to accommodate subsequent changes in the trade-off equilibrium.

Connected through hyperedge HE-1 (induced by source paper "the current state of affairs in 5g security and the main remaining security challenges"):
  with members:
    - "security and protocol exploit analysis of the 5g specifications"
    - "defeating the downgrade attack on identity privacy in 5g"
    - "formal analysis of 5g authentication"
    - "lte security protocol exploits and location tracking experimentation with low cost software radio"
    - "srslte an open source platform for lte evolution and experimentation"

Connected through hyperedge HE-2 (induced by source paper "csai open source cellular radio access network security analysis instrument"):
  with members:
    - "security and protocol exploit analysis of the 5g specifications"
    - "lte phy layer vulnerability analysis and testing using open source sdr tools"
    - "performance analysis of a mission critical portable lte system in targeted rf interference"
    - "lte security protocol exploits and location tracking experimentation with low cost software radio"
    - "srslte an open source platform for lte evolution and experimentation"

Connected through hyperedge HE-3 (induced by source paper "security and protocol exploit analysis of the 5g specifications"):
  with members:
    - "defeating the downgrade attack on identity privacy in 5g"
    - "formal analysis of 5g authentication"
    - "the 5g aka authentication protocol privacy"
    - "lte phy layer vulnerability analysis and testing using open source sdr tools"
    - "extending lte into the unlicensed spectrum technical analysis of the proposed variants"
    - "performance analysis of a mission critical portable lte system in targeted rf interference"
    - "lte security protocol exploits and location tracking experimentation with low cost software radio"
    - "five disruptive technology directions for 5g"

Connected through hyperedge HE-4 (induced by source paper "5g nr jamming spoofing and sniffing threat assessment and mitigation"):
  with members:
    - "lte phy layer vulnerability analysis and testing using open source sdr tools"
    - "on error correction performance and implementation of polar code list decoders for 5g"
    - "performance analysis of a mission critical portable lte system in targeted rf interference"
    - "lte security protocol exploits and location tracking experimentation with low cost software radio"
    - "vulnerability of lte to hostile interference"

Connected through hyperedge HE-5 (induced by source paper "the 5g aka authentication protocol privacy"):
  with members:
    - "formal analysis of 5g authentication"
    - "formal computational unlinkability proofs of rfid protocols"
    - "the applied pi calculus mobile values new names and secure communication"

Connected through hyperedge HE-6 (induced by source paper "formal analysis of 5g authentication"):
  with members:
    - "on security research towards future mobile network generations"

Connected through hyperedge HE-7 (induced by source paper "on security research towards future mobile network generations"):
  with members:
    - "lte phy layer vulnerability analysis and testing using open source sdr tools"
    - "control flow integrity precision security and performance"
    - "lte security protocol exploits and location tracking experimentation with low cost software radio"
    - "srslte an open source platform for lte evolution and experimentation"
    - "retrofitting mutual authentication to gsm using rand hijacking"
    - "improving air interface user privacy in mobile telephony"
    - "vulnerability of lte to hostile interference"

Connected through hyperedge HE-8 (induced by source paper "easy 4g lte imsi catchers for non programmers"):
  with members:
    - "lte security protocol exploits and location tracking experimentation with low cost software radio"
    - "srslte an open source platform for lte evolution and experimentation"

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)