human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "improving hard disk contention based covert channel in cloud computing environment"):
  Abstract: Steganographic methods allow the covert exchange of secret data between parties aware of the procedure. The cloud computing environment is a new and emerging target for steganographers, but currently not many solutions have been proposed. This paper proposes CloudSteg, which is a steganographic method that creates a covert channel based on hard disk contention between the two cloud instances that reside on the same physical machine. Experimental results conducted using open-source cloud environment OpenStack show that CloudSteg is able to achieve a bandwidth of about 0.1 bps, which is 1000 times higher than is known from the state-of-the-art version.

Includes members:
  Member "principles and overview of network steganography":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "real time steganalysis for stream media based on multi channel convolutional sliding windows")
  Member "is cloud computing steganography proof":
    also connected through other hyperedges:
      (none)
  Member "determinating timing channels in compute clouds":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "identifying cache based side channels through secret augmented abstract interpretation")

Question: Please tell me which class the source paper 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)