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: "using transcoding for hidden communication in ip telephony"
  Abstract: The paper presents a new steganographic method for IP telephony called TranSteg (Transcoding Steganography). Typically, in steganographic communication it is advised for covert data to be compressed in order to limit its size. In TranSteg it is the overt data that is compressed to make space for the steganogram. The main innovation of TranSteg is to, for a chosen voice stream, find a codec that will result in a similar voice quality but smaller voice payload size than the originally selected. Then, the voice stream is transcoded. At this step the original voice payload size is intentionally unaltered and the change of the codec is not indicated. Instead, after placing the transcoded voice payload, the remaining free space is filled with hidden data. TranSteg proof of concept implementation was designed and developed. The obtained experimental results are enclosed in this paper. They prove that the proposed method is feasible and offers a high steganographic bandwidth. TranSteg detection is difficult to perform when performing inspection in a single network localisation.

Connected through hyperedge HE-1 (induced by source paper "movesteg a method of network steganography detection"):
  with members:
    - "the good the bad and the ugly evaluation of wi fi steganography"
    - "on steganography in lost audio packets"
    - "information hiding using improper frame padding"

Connected through hyperedge HE-2 (induced by source paper "micro protocol engineering for unstructured carriers on the embedding of steganographic control protocols into audio transmissions"):
  with members:
    - "on covert acoustical mesh networks in air"
    - "new security and control protocol for voip based on steganography and digital watermarking"

Connected through hyperedge HE-3 (induced by source paper "hidden and uncontrolled on the emergence of network steganographic threats"):
  with members:
    - "a pattern based survey and categorization of network covert channel techniques"
    - "steganography in modern smartphones and mitigation techniques"
    - "stegtorrent a steganographic method for the p2p file sharing service"
    - "voip steganography and its detection a survey"
    - "padsteg introducing inter protocol steganography"
    - "sending hidden data via google suggest"
    - "how hidden can be even more hidden"
    - "steganographic routing in multi agent system environment"

Connected through hyperedge HE-4 (induced by source paper "steganography in modern smartphones and mitigation techniques"):
  with members:
    - "steganography using the extensible messaging and presence protocol xmpp"
    - "stegtorrent a steganographic method for the p2p file sharing service"
    - "principles and overview of network steganography"
    - "voip steganography and its detection a survey"
    - "lost audio packets steganography the first practical evaluation"
    - "capacity of steganographic channels"
    - "lack a voip steganographic method"

Connected through hyperedge HE-5 (induced by source paper "systemization of pluggable transports for censorship resistance"):
  with members:
    - "a framework for the game theoretic analysis of censorship resistance"
    - "games without frontiers investigating video games as a covert channel"
    - "on modeling the costs of censorship"
    - "dimming the internet detecting throttling as a mechanism of censorship in iran"
    - "the velocity of censorship high fidelity detection of microblog post deletions"
    - "scramblesuit a polymorph network protocol to circumvent censorship"
    - "sweet serving the web by exploiting email tunnels"

Connected through hyperedge HE-6 (induced by source paper "voip steganography and its detection a survey"):
  with members:
    - "influence of speech codecs selection on transcoding steganography"
    - "steganalysis of transcoding steganography"
    - "lost audio packets steganography the first practical evaluation"
    - "what are suspicious voip delays"
    - "steganography of voip streams"
    - "lack a voip steganographic method"
    - "covert channels in sip for voip signalling"
    - "new security and control protocol for voip based on steganography and digital watermarking"

Connected through hyperedge HE-7 (induced by source paper "influence of speech codecs selection on transcoding steganography"):
  with members:
    - "speex a free codec for free speech"
    - "padsteg introducing inter protocol steganography"
    - "steganography of voip streams"
    - "lack a voip steganographic method"
    - "new security and control protocol for voip based on steganography and digital watermarking"

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)