Jun 2014, Volume 8 Issue 3
    

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  • EDITORIAL
    Xiangke LIAO
  • RESEARCH ARTICLE
    Xiangke LIAO,Liquan XIAO,Canqun YANG,Yutong LU

    On June 17, 2013, MilkyWay-2 (Tianhe-2) supercomputer was crowned as the fastest supercomputer in the world on the 41th TOP500 list. This paper provides an overview of the MilkyWay-2 project and describes the design of hardware and software systems. The key architecture features of MilkyWay-2 are highlighted, including neo-heterogeneous compute nodes integrating commodity-off-the-shelf processors and accelerators that share similar instruction set architecture, powerful networks that employ proprietary interconnection chips to support the massively parallel message-passing communications, proprietary 16-core processor designed for scientific computing, efficient software stacks that provide high performance file system, emerging programming model for heterogeneous systems, and intelligent system administration. We perform extensive evaluation with wide-ranging applications from LINPACK and Graph500 benchmarks to massively parallel software deployed in the system.

  • RESEARCH ARTICLE
    Zhengbin PANG,Min XIE,Jun ZHANG,Yi ZHENG,Guibin WANG,Dezun DONG,Guang SUO

    Interconnection network plays an important role in scalable high performance computer (HPC) systems. The TH Express-2 interconnect has been used in MilkyWay-2 system to provide high-bandwidth and low-latency interprocessor communications, and continuous efforts are devoted to the development of our proprietary interconnect. This paper describes the state-of-the-art of our proprietary interconnect, especially emphasizing on the design of network interface. Several key features are introduced, such as user-level communication, remote direct memory access, offload collective operation, and hardware reliable end-to-end communication, etc. The design of a low level message passing infrastructures and an uppermessage passing services are also proposed. The preliminary performance results demonstrate the efficiency of the TH interconnect interface.

  • RESEARCH ARTICLE
    Weixia XU,Yutong LU,Qiong LI,Enqiang ZHOU,Zhenlong SONG,Yong DONG,Wei ZHANG,Dengping WEI,Xiaoming ZHANG,Haitao CHEN,Jianying XING,Yuan YUAN

    With the rapid improvement of computation capability in high performance supercomputer system, the imbalance of performance between computation subsystem and storage subsystem has become more and more serious, especially when various big data are produced ranging from tens of gigabytes up to terabytes. To reduce this gap, large-scale storage systems need to be designed and implemented with high performance and scalability. MilkyWay-2 (TH-2) supercomputer system with peak performance 54.9 Pflops, definitely has this kind of requirement for storage system. This paper mainly introduces the storage system in MilkyWay-2 supercomputer, including the hardware architecture and the parallel file system. The storage system in MilkyWay-2 supercomputer exploits a novel hybrid hierarchy storage architecture to enable high scalability of I/O clients, I/O bandwidth and storage capacity. To fit this architecture, a user level virtualized file system, named H2FS, is designed and implemented which can cooperate local storage and shared storage together into a dynamic single namespace to optimize I/O performance in IO-intensive applications. The evaluation results show that the storage system in MilkyWay-2 supercomputer can satisfy the critical requirements in large scale supercomputer, such as performance and scalability.

  • RESEARCH ARTICLE
    Kai LU,Xiaoping WANG,Gen LI,Ruibo WANG,Wanqing CHI,Yongpeng LIU,Hongwei TANG,Hua FENG,Yinghui GAO

    With the increase of system scale, the inherent reliability of supercomputers becomes lower and lower. The cost of fault handling and task recovery increases so rapidly that the reliability issue will soon harm the usability of supercomputers. This issue is referred to as the “reliability wall”, which is regarded as a critical problem for current and future supercomputers. To address this problem, we propose an autonomous fault-tolerant system, named Iaso, in MilkyWay-2 system. Iaso introduces the concept of autonomous management in supercomputers. By autonomous management, the computer itself, rather than manpower, takes charge of the fault management work. Iaso automatically manage the whole lifecycle of faults, including fault detection, fault diagnosis, fault isolation, and task recovery. Iaso endows the autonomous features with MilkyWay-2 system, such as self-awareness, self-diagnosis, self-healing, and self-protection. With the help of Iaso, the cost of fault handling in supercomputers reduces from several hours to a few seconds. Iaso greatly improves the usability and reliability of MilkyWay-2 system.

  • RESEARCH ARTICLE
    Najme MANSOURI

    Data Grid integrates graphically distributed resources for solving data intensive scientific applications. Effective scheduling in Grid can reduce the amount of data transferred among nodes by submitting a job to a node, where most of the requested data files are available. Scheduling is a traditional problem in parallel and distributed system. However, due to special issues and goals of Grid, traditional approach is not effective in this environment any more. Therefore, it is necessary to propose methods specialized for this kind of parallel and distributed system. Another solution is to use a data replication strategy to createmultiple copies of files and store them in convenient locations to shorten file access times. To utilize the above two concepts, in this paper we develop a job scheduling policy, called hierarchical job scheduling strategy (HJSS), and a dynamic data replication strategy, called advanced dynamic hierarchical replication strategy (ADHRS), to improve the data access efficiencies in a hierarchical Data Grid. HJSS uses hierarchical scheduling to reduce the search time for an appropriate computing node. It considers network characteristics, number of jobs waiting in queue, file locations, and disk read speed of storage drive at data sources. Moreover, due to the limited storage capacity, a good replica replacement algorithm is needed. We present a novel replacement strategy which deletes files in two steps when free space is not enough for the new replica: first, it deletes those files with minimum time for transferring. Second, if space is still insufficient then it considers the last time the replica was requested, number of access, size of replica and file transfer time. The simulation results show that our proposed algorithm has better performance in comparison with other algorithms in terms of job execution time, number of intercommunications, number of replications, hit ratio, computing resource usage and storage usage.

  • RESEARCH ARTICLE
    Lei XIE,Sanglu LU,Yingchun CAO,Daoxu CHEN

    Data storage has become an important issue for energy efficient data management in sensor networks. In this paper, we investigate the optimized storage placement problem in large scale sensor networks, aiming to achieve minimized energy cost. In order to efficiently deal with large scale deployment areas with irregular shape, we propose to utilize the hop as the computation unit instead of the node, such that computation complexity can be greatly reduced. We propose methodologies to solve the optimization problem both in situations for limited and unlimited numbers of storage units. The ultimate goal of this paper is to give fundamental guidance for optimized storage placement in large scale sensor networks. Simulation results show that our methodologies can greatly reduce the overall energy consumption compared to other strategies.

  • RESEARCH ARTICLE
    Jingyuan WANG,Jiangtao WEN,Yuxing HAN,Jun ZHANG,Chao LI,Zhang XIONG

    The transport control protocol (TCP) has been widely used in wired and wireless Internet applications such as FTP, email and HTTP. Numerous congestion avoidance algorithms have been proposed to improve the performance of TCP in various scenarios, especially for high speed and wireless networks. Although different algorithms may achieve different performance improvements under different network conditions, designing a congestion algorithm that can perform well across a wide spectrum of network conditions remains a great challenge. Delay-based TCP has a potential to overcome above challenges. However, the unfairness problem of delay-based TCP with TCP Reno blocks widely the eployment of delay-based TCP over wide area networks. In this paper, we proposed a novel delay-based congestion control algorithm, named FAST-FIT, which could perform gracefully in both ultra high speed networks and wide area networks, as well as keep graceful fairness with widely deployed TCP Reno hosts. FAST-FIT uses queuing delay as a primary input for controlling TCP congestion window. Packet loss is used as a secondary signal to adaptively adjust parameters of primary control process. Theoretical analysis and experimental results show that the performance of the algorithm is significantly improved as compared to other state-of-the-art algorithms, while maintaining good fairness.

  • RESEARCH ARTICLE
    Yanfei LV,Bin CUI,Xuexuan CHEN,Jing LI

    Flash solid-state drives (SSDs) provide much faster access to data compared with traditional hard disk drives (HDDs). The current price and performance of SSD suggest it can be adopted as a data buffer between main memory and HDD, and buffer management policy in such hybrid systems has attracted more and more interest from research community recently. In this paper, we propose a novel approach to manage the buffer in flash-based hybrid storage systems, named hotness aware hit (HAT). HAT exploits a page reference queue to record the access history as well as the status of accessed pages, i.e., hot, warm, and cold. Additionally, the page reference queue is further split into hot and warm regions which correspond to the memory and flash in general. The HAT approach updates the page status and deals with the page migration in the memory hierarchy according to the current page status and hit position in the page reference queue. Compared with the existing hybrid storage approaches, the proposed HAT can manage the memory and flash cache layers more effectively. Our empirical evaluation on benchmark traces demonstrates the superiority of the proposed strategy against the state-of-the-art competitors.

  • RESEARCH ARTICLE
    Mingwu ZHANG,Yi MU

    In order to tolerate possible leakage of secret keys, leakage-resilient cryptosystem models a class of attractive leakage output by allowing an adversary to provide any computable leakage function and learning the partial keys or other possible internal states from the output of function. In this work, we present an adaptively secure broadcast encryption resilient to key continual leakage in the standard model. Our scheme provides the tolerance of continual leakage, in which any user can generate multiple private keys per user by periodically updating the key. We use the dual system encryption mechanism to implement the leakage resilience and adaptive security, and intrinsically set an algorithm to refresh a key and produce a same distributed new key. We also give the evaluation of the leakage bound and leakage fraction, and the simulations show that our scheme can tolerate about 71% leakage fraction with 3.34 × 10-52 failure probability in standard 80-bit security level when we adjust the leakage factor to allow the private key to be 100 Kb.

  • RESEARCH ARTICLE
    Qiqi LAI,Yuan CHEN,Yupu HU,Baocang WANG,Mingming JIANG

    Key-dependent message (KDM) security is an important security issue that has attracted much research in recent years. In this paper, we present a new construction of the symmetric encryption scheme in the the ideal cipher model (ICM); we prove that our scheme is KDM secure against active attacks with respect to arbitrary polynomialtime challenge functions. Our main idea is to introduce a universal hash function (UHF) h as a random value for each encryption, and then use s = h(sk) as the key of the ideal cipher F, where sk is the private key of our symmetric encryption scheme. Although many other schemes that are secure against KDM attacks have already been proposed, in both the ideal standard models, the much more significance of our paper is the simplicity in which we implement KDM security against active attacks.

  • RESEARCH ARTICLE
    Chang-ai SUN,Zuoyi WANG,Guan WANG

    In recent years, a variety of encryption algorithms were proposed to enhance the security of software and systems. Validating whether encryption algorithms are correctly implemented is a challenging issue. Software testing delivers an effective and practical solution, but it also faces the oracle problem (that is, under many practical situations, it is impossible or too computationally expensive to know whether the output for any given input is correct). In this paper, we propose a property-based approach to testing encryption programs in the absence of oracles. Our approach makes use of the so-called metamorphic properties of encryption algorithms to generate test cases and verify test results. Two case studies were conducted to illustrate the proposed approach and validate its effectiveness. Experimental results show that even without oracles, the proposed approach can detect nearly 50% inserted faults with at most three metamorphic relations (MRs) and fifty test cases.

  • RESEARCH ARTICLE
    Haibo TIAN,Jin LI

    A non-delegatable strong designated verifier signature (NSDVS) enforces verification of a signature by a designated verifier only. The concept is useful in various commercial cryptographic applications such as copyright protection, e-voting, and e-libraries. This paper reports the shortest NSDVS so far that consists of only two elements. The scheme is inspired by an identification scheme and Cramer et al.’s OR-proof technique where a prover can prove that he knows at least one out two secrets. It is solidified by a symmetric key based group to group encryption algorithm. Two implementations of the algorithm are reported. The scheme is provably secure with respect to its properties of unforgeability, non-transferability, privacy of signer’s identity, and non-delegatability.

  • RESEARCH ARTICLE
    Solomon Guadie WORKU,Chunxiang XU,Jining ZHAO

    An auditing scheme is a good way to prove owner’s data outsourced to the cloud are kept intact, and a scheme capable of giving public verifiability service is a good option that some researchers have managed to build for the last few years. However, in a public auditing scheme everybody does verification of data and a possibility of leaking some secrete information to the public verifiers is an issue that data owners are unhappy with this scenario. For example, the data owner does not want anybody else to know he has the data stored in the cloud server. Motivated by the issue of privacy associated with public auditing system, we proposed a designated verifier auditing (DVA) scheme based on Steinfeld et al.’s universal designated verifier (DV) signature scheme. Our DVA scheme authorizes a third party auditor with private verification capability. It provides private verification because the scheme involves private key of the verifier. Moreover, we present the batch auditing scheme to improve auditing efficiency. Through rigorous security analysis we showed that our scheme is provably secure in the random oraclemodel assuming that the computational Diffie-Hellman (CDH) problem is hard over the group of bilinear maps.

  • RESEARCH ARTICLE
    Le DONG,Wenling WU,Shuang WU,Jian ZOU

    We present some known-key distinguishers for a type-1 Feistel scheme with a permutation as the round function. To be more specific, the 29-round known-key truncated differential distinguishers are given for the 256-bit type-1 Feistel scheme with an SP (substitution-permutation) round function by using the rebound attack, where the S–boxes have perfect differential and linear properties and the linear diffusion layer has a maximum branch number. For two 128-bit versions, the distinguishers can be applied on 25-round structures. Based on these distinguishers, we construct near-collision attacks on these schemes with MMO (Matyas-Meyer-Oseas) and MP (Miyaguchi-Preneel) hashing modes, and propose the 26-round and 22-round near-collision attacks for two 256-bit schemes and two 128-bit schemes, respectively. We apply the near-collision attack on MAME and obtain a 26-round near-collision attack. Using the algebraic degree and some integral properties, we prove the correctness of the 31-round known-key integral distinguisher proposed by Sasaki et al. We show that if the round function is a permutation, the integral distinguisher is suitable for a type-1 Feistel scheme of any size.