区块链技术在供应链管理中的应用研究

传统供应链模式已经无法适应高速发展的经济,因此需要通过信息技术寻求合适的机制。文章通过分析传统供应链模式中存在的商品质量与合同管理问题,研究了区块链、智能合约技术在商品溯源、减少合同纠纷方面的优势,展望了区块链技术的发展趋势。     

Survey on blockchain-based non-fungible tokens: History,technologies, standards,and open challenges

This paper presents a survey of non-fungible tokens (NFTs), including its history, technologies, standards, and challenges in their development. An NFT is a unique digital entity that is created and maintained using blockchain technology. Each NFT is identified using a unique smart contract and a token ID, so the whole history of the NFT can be globally identified by its address and token ID. The blockchain information indelibly identifies the current owner of any asset, previous owners, and original creator. NFTs are used to manage ownership of digital and physical assets and cryptocurrencies. The prices of popular NFTs have become very high, and the market for them has overheated in recent years. NFT technology and its ecosystem have evolved since Quantum, the first NFT, was stored in the Namecoin blockchain. Ethereum has become the main platform for NFT projects because it provides support for smart contracts. Currently, almost all NFT projects are launched on the Ethereum blockchain. NFT has two major standards called ERC-721 and ERC-1155, which have had important functions in the development of NFT. Starting with these two standards, other standards for NFT continue to emerge; they expand the functionality of NFT such as by adding utility. However, NFT is a very early technology, and it has not been long after the NFT concept was created and used. So there are several challenges for further improving NFT technology, in terms of usability, interoperability, and evolution. This paper presents a survey of NFT, including its history, technologies, standards, and challenges of NFT.     

Design and performance comparison of multiple-token based MAC protocols for optical burst switched ring networks

Optical burst switching (OBS) has been proposed as a new optical switching paradigm for the next generation Internet due to its flexibility and feasibility compared to OCS and OPS. Moreover, serving as a backbone that interconnects a number of access networks, OBS ring topologies have been a good choice for solving the current metro gap problem between core network and access network owning to its simplicity and scalability. In this paper, we provide an insight into the OBS ring network that consists of nodes using TT–TR (Tunable Transmitter–Tunable Receiver). The node architectures with TT–TR may make efficient use of network resources even though traffic pattern, such as IP traffic with self-similarity dynamically change, and can support good expandability. However, all nodes share the limited network resources. This may result in contention such as wavelength contention and transceiver contention leading to burst loss. In order to use the shared network resources fairly and efficiently as well as reducing the resource contention, we focus on the design of medium access control (MAC) protocols based on multiple tokens. Each token is allocated to one wavelength to denote the accessibility of that wavelength, i.e., once the token is captured, the corresponding wavelength can be used to transmit a burst. As tokens hold the key for using wavelengths to transmit bursts, token management including the token release time is crucial in the proposed MAC protocols. Thus, two kinds of multiple-token based MAC protocols with different token release times are proposed: token release after transmitting burst (TRTB) and token release after transmitting control header (TRTC). Each of them is classified into two schemes called TRTB/TRR and TRTB/RCA and correspondingly TRTC/TRR and TRTC/ RCA. RCA stands for receive collision avoidance. The target is to increase the performance while reducing the processing overhead at each node. The performance of the TRTB and TRTC protocols are evaluated and compared in terms of queuing delay, burst loss rate, and channel utilization by OPNET simulation. The effects of various design parameters are also investigated through simulation in order to evaluate their scalability. In all the proposed schemes, tokens are just used to denote the accessibility of each wavelength. Finally, as an alternative, we also propose a new scheme based on the TRTC protocol called TRTC/CAT (collision avoidance by tokens) to avoid contention by using tokens.

Extension of prioritized data analysis in the Foundation Fieldbus to three classes

The Foundation Fieldbus data link layer provides both a token‐passing service required for sporadic data and a scheduled service for periodic data. It has three priority levels: urgent, normal, and time‐available. Modeling the virtual token rotation time (VTRT), which is the time required to receive tokens for the transmission of one's own data, is difficult due to the interactive data delay driven by the three priority levels. Therefore, a simplified mathematical model consisting of just two priority levels has been considered. In a previous research, the VTRT probability density function was defined using the probability of a token generation; however in the present study, a simpler expression was successfully developed in a system of three priority levels by tracking the token's priority changes generated by the link active scheduler. These priority changes are tracked by using the state transition probability and the state transition diagram of a token. Therefore, the success of this new mathematical model makes this research important. Furthermore, we found the existence and the cause of a fluctuating state, both of which are useful to a system designer for setting network parameters. The validity of the analytical model was verified in a simulation experiment. Copyright © 2011 John Wiley & Sons, Ltd.     

区块链的应用：安全威胁与解决策略

区块链技术具有去中心化、可追溯性和去信任化等特性,已被广泛应用于诸多领域。然而,人们往往忽略区块链自身的安全问题,较少有相关问题研究及解决方案的成果。文章着重剖析区块链所受安全威胁问题并提出其安全保护措施,从技术风险、内容风险等不同视角阐释区块链所受的安全攻击,在多个层面给出了区块链的安全保护机制,尤其对日蚀攻击防御中IP地址信用评价模型进行了思索。最后,从技术和监管两个方面,对区块链技术的发展进行了展望。     

区块链的应用:安全威胁与解决策略

区块链技术具有去中心化、可追溯性和去信任化等特性,已被广泛应用于诸多领域.然而,人们往往忽略区块链自身的安全问题,较少有相关问题研究及解决方案的成果.文章着重剖析区块链所受安全威胁问题并提出其安全保护措施,从技术风险、内容风险等不同视角阐释区块链所受的安全攻击,在多个层面给出了区块链的安全保护机制,尤其对日蚀攻击防御中...     

Algorithm of blockchain data provenance based on ABE

To solve the problem that the blockchain-based traceability algorithm mainly used homomorphic encryption and zero-knowledge proof for privacy protection,making it difficult to achieve dynamic sharing of traceability information,a blockchain data traceability algorithm based on attribute encryption was proposed.In order to realize the dynamic protection of transaction privacy,the strategy update algorithm applicable to block chain was designed based on the CP-ABE scheme proposed by Waters to achieve dynamic protection of transaction privacy.In order to realize the dynamic update of the visibility about block content,based on the strategy update algorithm,the block structure was designed to achieve the dynamic update about the content visibility of the block.The security and experimental simulation analysis show that the proposed algorithm can realize the dynamic sharing of traceability information while completing the protection transaction privacy.     

区块链用户匿名与可追踪技术

区块链具有透明性、数据完整性、防篡改等优点,在金融、政府、军事等领域有重要应用价值。目前有越来越多的工作研究区块链的隐私保护问题,典型的包括门罗币、Zerocash, Mixcoin等等。这些隐私保护方法可以用于保护区块链上用户的身份和交易的金额。隐私保护方案是双刃剑,一方面是对合法用户隐私的完善保护,另一方面如果完全脱离监管,则是对洗钱、勒索等违法犯罪行为的姑息和纵容。针对区块链上各种层出不穷的隐私保护方案,监管也要与时俱进。该文研究区块链用户身份的隐私保护和监管方法,提出了用户匿名和可追踪的技术,旨在推动区块链在实际中的应用。     

IWTRP: Spatial-reuse Enhancement of the Wireless Token Ring Protocol

This work presents an improved wireless token ring protocol (IWTRP) for wireless metropolitan area networks (W-MANs) adopting a ring topology. Opposed to the single token and transmission permitted in WTRP, IWTRP provides a novel method to allow for multiple tokens, and thus multiple simultaneous transmissions in the ring. IWTRP employs both the request-to-send/clear-to-send (RTS/CTS) handshaking and the network allocation vector (NAV) updating techniques to resolve collision-resolution and token-elimination problems resulted from multiple tokens. The normalized saturation throughput of IWTRP is analytically characterized and verified through simulations.     

基于新型公平盲签名和属性基加密的食用农产品溯源方案

为解决食用农产品溯源中存在的身份隐私易泄露、难监管以及溯源数据共享困难等问题,该文提出一种基于新型公平盲签名和属性基加密的食用农产品溯源方案。该方案在联盟链授权访问、不可篡改特性的基础上,结合椭圆曲线和零知识证明提出一种新型公平盲签名方法,实现了食用农产品数据上传者身份条件匿名并通过双重ID机制避免了签名方陷害问题;方案同时采用Asmuth-Bloom门限改进的属性基加密结合智能合约技术实现了权限分层的食用农产品溯源数据秘密共享。各项分析及实验结果表明,该方案具备良好的安全性和功能性。     

Design and implementation of labor arbitration system based on blockchain

Data island and information opacity are two major problems in collaborative administration. Blockchain has the potential to provide a trustable and transparent environment encouraging data sharing among administration members. However, the blockchain only stores Hash values and transactions in blocks which makes it unable to store big data and trace their changes. In this paper, a labor arbitration scheme based on blockchain was proposed to share labor arbitration data. In the system, a collaborative administration scheme that provides a big data storage model combined blockchain and interplanetary file system ( IPFS) is designed. It can store big data and share these data among different parties. Moreover, a file version control mechanism based on blockchain is designed to manage the data changes in IPFS network. It creates a tracing chain that consists of many IPFS objects to track changes of stored data. The relationship of previous and current IPFS objects recorded by blockchain can describe the changes of administration data and trace the data operations. The proposed platform is used in Rizhao City in China, and the experiment result shows collaborative administration scheme achieves traceability with high throughput and is more efficient than traditional hypertext transfer protocol ( HTTP) way to share data.     

Performance analysis of a rate-control throttle where tokens andjobs queue

A rate-control throttle is used for overload control in distributed switching systems and computer and communication networks. Typical implementations of the throttle have a token bank where an arriving job is blocked and rejected if the bank is empty of tokens. The author examines an expanded implementation where an arriving job queues in a finite buffer when the token bank is empty. It is shown that the steady-state throughput and blocking of jobs depends on the capacity of the job buffer and the capacity of the token bank only via the sum of the two capacities, not on their individual values. Thus, the job buffer per se is not needed to enhance the robustness of the throughput of the throttle to unknown exogenous job arrival rates. However, a job buffer (along with a token bank) with adjustable buffer capacities does have the potential to shape the departure process and to adapt between a delay control and a work-rejection control     

Cooperative Transmissions in 5G Large-scale Relay Systems: How to Keep a Balance Between Performance and Complexity?

This paper presents a generalized i-vector representation framework with phonetic tokenization and tandem features for text independent as well as text dependent speaker verification. In the conventional i-vector framework, the tokens for calculating the zero-order and first-order Baum-Welch statistics are Gaussian Mixture Model (GMM) components trained from acoustic level MFCC features. Yet besides MFCC, we believe that phonetic information makes another direction that can benefit the system performance. Our contribution in this paper lies in integrating phonetic information into the i-vector representation by several extensions, forming a more generalized i-vector framework. First, the tokens for calculating the zero-order statistics is extended from the MFCC trained GMM components to phonetic phonemes, trigrams and tandem feature trained GMM components, using phoneme posterior probabilities. Second, given the zero-order statistics (posterior probabilities on tokens), the feature used to calculate the first-order statistics is also extended from MFCC to tandem feature, and is not necessarily the same feature employed by the tokenizer. Third, the zero-order and first-order statistics vectors are then concatenated and represented by the simplified supervised i-vector approach followed by the standard Probabilistic Linear Discriminant Analysis (PLDA) back-end. We study different token and feature combinations, and we show that the feature level fusion of acoustic level MFCC features and phonetic level tandem features with GMM based i-vector representation achieves the best performance for text independent speaker verification. Furthermore, we demonstrate that the phonetic level phoneme constraints introduced by the tandem features help the text dependent speaker verification system to reject wrong password trials and improve the performance dramatically. Experimental results are reported on the NIST SRE 2010 common condition 5 female part task and the RSR 2015 part 1 female part task for text independent and text dependent speaker verification, respectively. For the text independent speaker verification task, the proposed generalized i-vector representation outperforms the i-vector baseline by relatively 53 % in terms of equal error rate (EER) and norm minDCF values. For the text dependent speaker verification task, our proposed approach also reduced the EER significantly from 23 % to 90 % relatively for different types of trials.     

Blockchain trading mechanism based on attached chain for the delay tolerant network

In order to deploy a blockchain on the non-continuous connectivity delay tolerant network,a blockchain trading mechanism was designed,which could run on this type of network.First,the identifier was introduced into the existing block structure and a block structure on the attached chain was presented,which could append the blocks generated during network disconnection.Then,the approaches including the block package,block mining and block consensus on the attached chain were proposed.Finally,a confirming consensus approach was presented to avoid block fraud in the process of appending the attached chain.Through theoretical proof and experimental analysis,the proposed mechanism can support blockchain trading in the delay tolerant network.     

Security Attack Safe Mobile and Cloud-based One-time Password Tokens Using Rubbing Encryption Algorithm

One-time Password (OTP) Token has become one of the main stream security products during the past few years. OTP Token can automatically generate a random password. It is especially popular to be used with the Two-factor Authentication (2FA) system. OTP Token has proliferated into many different form factors such as standalone token, PC, PDA, cellular phone and Cloud-based token. But most of the implementation has their short comings with high token cost, not easy to carry and high supporting or deployment cost. Certain implementations may also compromise the network security when the token is lost or stolen. Moreover, most of the tokens can be broken-in by Man-in-the-Middle Seed-tracing and Shoulder-surfing security attacks. To overcome such aforementioned issues, we propose a secure encryption algorithm – Rubbing Encryption Algorithm (REAL). We use REAL to implement a Mobile-based and a Cloud-based OTP Token as design examples. Both of them are of high security level, lower total token cost and can resist the aforementioned security attacks as well.     

基于区块链的威胁情报共享及评级技术研究

随着计算机和网络技术的快速发展,网络安全事件频发,安全漏洞不断,威胁情报的作用和价值越来越大。基于区块链的开放、共识、自治和去中心、去信任、不可篡改、可追溯等特点,提出了通过区块链技术构建威胁情报信息的区块,包括IP地址信息、域名信息、URL信息、安全事件信息、漏洞信息、威胁情报源可信度、威胁情报源贡献率等;并设计了基于区块链的威胁情报共享和评级系统,给出了相应的基于区块链的威胁情报共享方法和评级方法,可以实现及时有效获取及分析出最新、最有价值的威胁情报信息,从而及时进行防护及应急响应,促进整个威胁情报生态的闭环持续有效开展。     

Burst reduction properties of the leaky bucket flow control schemein ATM networks

The leaky bucket is a simple flow control scheme for ATM networks. An arriving cell can be transmitted only if it finds a token in the token buffer, in which case it is transmitted instantaneously by consuming a token. If the token buffer is empty, the cell has to wait until the generation of a new token. For purposes of analysis the authors assume an infinite cell buffer. The control parameter is the token buffer size C. The authors examine the burstiness of the output how as a function of C and show that the burstiness increases with C. In particular the output flow is always less bursty than the input flow. This monotonicity simplifies optimal choice of the token buffer size. The result is true for fairly arbitrary input flows and deterministic token generation times     

Transport of IP controlled-load service over ATM networks

A hot topic in the research community is the interworking of integrated IP services, defined by the IETF, with ATM, a technology designed for the transport of multimedia traffic. In particular, the IETF recommends the ATM CBR, nrt-VBR, and ABR service classes for the transport of controlled-load service (CLS) over ATM. In this work the first two alternatives are examined and compared, in order to determine which is the most convenient for CLS. The comparison is carried out in terms of QoS and amount of buffering required at the IP/ATM routers. These performance parameters strongly depend on the parameters of the CLS token bucket shaper, that is, the token bucket depth and token bucket input buffer capacity. A nrt-VBR connection is able to offer a given performance level over a range of values of the token bucket parameters wider than that permitted by a CBR connection. Moreover, in all the examined cases the nrt-VBR connection needs a relatively small ATM buffer at the IP/ATM routers. Since, in order to guarantee acceptable performance, some CLS requests must be rejected, the utilization of the ATM link can be relatively low; this drawback can be overcome by serving the rejected CLS requests as classic best-effort traffic     

基于令牌漏桶法的数据记录技术

针对实时系统记录数据会引起系统运行速度缓慢、瘫痪、甚至＂死机＂的问题,提出了具有特色的令牌漏桶法。该方法通过创建循环队列数据池并根据数据池的数据量适时发放令牌和拥有令牌的任务自动选择CPU空闲时执行等技术实现。通过试验验证,在保证整个系统实时性、可靠性的前提下,该方法实现了实时记录数据的功能。