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: "proposed video encryption algorithm v s other existing algorithms a comparative study"
  Abstract: multimedia data has become of utmost importance especially in the applications related to military purposes. With the rise in development in computer and internet technology, multimedia data has become the most convenient method for military training. An innovative encryption algorithm for videos compressed using H.264 was proposed to safely exchange highly confidential videos. To maintain a balance between security and computational time, the proposed algorithm shuffles the video frames along with the audio, and then AES is used to selectively encrypt the sensitive video codewords. Using this approach unauthorized viewing of the video file can be prevented and hence this algorithm provides a high level of security. A comparative study of the proposed algorithm with other existing algorithms has been put forward in this paper to prove the effectiveness of the proposed algorithm.

Connected through hyperedge HE-1 (induced by source paper "an open source p2p encrypted voip application"):
  with members:
    - "comparative study of qos parameters of sip protocol in 802 11a and 802 11b network"
    - "new security and control protocol for voip based on steganography and digital watermarking"
    - "an analysis of the skype peer to peer internet telephony protocol"

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)