Implementation and Analysis of Minimum Starting-tag Fair Queuing

隨著網路技術的快速發展，相對應的需求也紛紛產生。其中如何在有限的頻寬服務之中，提供服務品質(quality of service)的保證，並滿足最多的服務要求更是一個重要的課題。在所有提供服務品質保證的努力之中，路由器上(Router)之封包排班演算法(packet scheduling algorithms)是影響最直接的部分。藉由封包排班演算法的發展，本論文期望能夠對有限頻寬之下服務品質的提供有所助益。 本論文將實作最小起始標籤公平排班法(MSFQ；Minimum Starting-tag Fair Queuing)，其為一個經理論證明具有良好延遲時間上限(Delay Bound)、公平性(Fairness)與演算法複雜度(Time Complexity)表現的封包排班演算法。並提供一個快速及有效率的時作平台，將時作網路測試環境的流程複雜度降至最低。 本論文以Linux為發展目標平台，依據Linux內部之Linux Advanced Routing計劃之架構，建構最小起始標籤公平排班法於Linux的核心(kernel)之中，並修改與Linux Advanced Routing相關之系統程式套件iproute2以啟動最小起始標籤公平排班法，最後得到一個以最小起始標籤公平排班法為封包排班演算法之路由器。 本論文將會驗證所提出的最小起始標籤公平排班法之延遲時間上限以及公平性，並與其他Linux中之封包排班演算法互相比較。藉由實際測試後分析結果我們將可得知本論文的最小起始標籤公平排班法為一個有效率、延遲時間表現良好的路由器演算法。本論文實作的過程，也提供了一個實作其他網路理論的參考，包括其他封包排班演算法、新的架構等皆可以使用本論文所建立的流程快速而有效率的加以完成。Minimum Starting-tag Fair Queuing (MSFQ)[1] is an efficient packet scheduling algorithm with theoretically proved in performance metrics such as delay bound, fairness, and time complexity. However, MSFQ algorithm didn't have any implementation yet. In this paper, we established a configurable routing system based on Linux with MSFQ as the routing scheduling algorithm. In the process of implementation, we designed and improved the internal part of data structures, embedded MSFQ algorithm into Linux kernel according to structures of Linux Network Traffic Control [2] extended from Linux advanced routing project called iproute2 [3]. In order to boot MSFQ from kernel, we also modified ‘tc' package in iproute2 project. An analysis model is built to evaluate the performance of proposed routing system. The comparison between MSFQ algorithm and other scheduling algorithms built in Linux kernel such as prio, sfq, etc. is also provided. The result of implementation proved the behaviors of MSFQ both theoretically and essentially. We also offered an easier and faster process to implement other algorithms so that any new algorithms will be implemented and verified more efficiently.1. 序論 1.1 研究動機 1.2 研究目的 1.3 論文架構 2. 文獻探討 2.1 Linux Advanced Routing: iproute2 2.2 其他Linux內建演算法 2.2.1 fifo (First-In-First-Out 2.2.2 tbf (Token Bucket Filter) 2.2.3 sfq (Stochastic Fair Queuing 2.2.4 prio (3-band Priority Scheduler 2.2.5 Other Queuing Disciplines 2.3 MSFQ 2.3.1 Generalized Process Sharing 2.3.2 Weighted Fair Queueing 2.3.3 MSFQ 3. 系統架構及實作步驟 3.1 程式流程 3.2 資料結構設計 3.3 複雜度分析 3.4 實作成果 4. 效能分析比較 4.1 分析模組(Analysis Models)與分析工具 4.2 實驗結果與比較 5. 討論與建議 5.1 實作過程之問題紀錄 5.2 討論 5.3 未來方向 參考文獻(Bibliography 附錄一 iproute2套件之程式碼修補檔 附錄二 Linux核心進階路由功能之程式碼修補

A Study on Novel Visual Secret Sharing Schemes

視覺密碼學(Visual Cryptography)是機密分享(Secret Sharing)領域下的一個新興領域，在原本機密分享的架構及環境下，多了一個解密不需要電腦運算的限制條件，分享影像交由參與者分別攜帶，只需要疊合起來就能觀看解密的結果。在這個新的特性之下，視覺密碼學在缺乏電腦運算能力、傳統技術無法運作時，仍然能夠正常進行解密，在緊急情況下提供一個良好的解決技術。在現有的視覺密碼學研究中，仍然有許多尚待改進的地方，例如目前絕大部分視覺密碼學方法所產生的分享影像在視覺上近似雜訊，若能使分享影像看來更自然，能夠有效的保護分享影像的安全。另外，仍未有技術能夠達到不同組合解出不同機密，同時在最基礎的兩張分享影像疊合時，也未能解密出多張的不同機密影像。 因此在本論文中，首先我們提出一個使分享影像具有意義的新方法，以像素轉換為基礎，比起現有方法具備更高機密解析度，而且能夠結合其他同類型方法達到更好的效果。接著，本論文提出了一個新的具備廣義型還原架構的視覺機密分享方法，不限制解密條件，同時可以讓各組參與者解密出不同的機密影像，進一步減少了限制條件。最後本論文提出一個視覺密碼學方法，能夠在兩張分享影像中藏入多張機密影像，使兩張分享影像可以一次藏入多量的機密，而不必攜帶多量的分享影像，比起現有方法只能將最多兩張機密影像藏入，依照本論文所推導出的關係公式，在放大倍率可以接受的狀況下，能解出任意張數的機密影像。本論文所提方法在現有技術的基礎上，深入研究視覺密碼學，以推廣其應用。Visual cryptography is a rising sub-field in the research of secret sharing. Except the properties of secret sharing, the decryption does not need any computation that the secret image reveals in human vision by just stacking the shares together. Therefore, visual cryptography is capable for emergency and special situations. However, there are plenty of rooms for improving in visual cryptography. For example, share images of current visual secret sharing schemes look like noise. It would be easy to hide the share images if the shares look like natural pictures. Also, different participants can only decrypt the same secret, and only one secret image can be decrypted from the participants. Therefore, we develop a new visual secret sharing scheme based on pixel swapping to generate two meaningful share images that the stacking results are better than existing schemes. In addition, the proposed scheme can cooperate with other schemes to enhance the quality. Then a new generalized visual secret sharing scheme is developed in this dissertation that different combination of shares can decrypt different secret images. Finally, a new idea to share multiple secret images in two share images is designed. Currently, the number of secrets is limited by two for two share images. According to the proposed relationship, the number is extended to general in our scheme with reasonable expanding ratio. The proposed schemes in this dissertation extend the research of visual cryptography and may be applied to more applications.致謝 I 中文摘要 II Abstract III Contents IV Contents of Tables VI Contents of Figures VII 1 Introduction 1 2 Related Works 10 2.1 Related Works of Meaningful Share Images 10 2.1.1 Error-Diffusion Halftoning Techniques 10 2.1.2 Data Hiding by Conjugate Error Diffusion 12 2.2 Related Works of Generalized Access Structure 14 2.2.1 Definition of an Access Structure 14 2.2.2 Visual Cryptography for General Access Structure 15 2.3 Related Works of Multiple Secrets 17 2.3.1 Chen and Wu''s Visual Secret Sharing Scheme for Two Secret Images 17 2.3.2 The Ring Shadow Image Technology 19 3 A Data Hiding Scheme Using Pixel Swapping for Halftone Images 23 3.1 The Proposed Scheme 23 3.2 Experimental Results 27 3.3 Analyses of the Proposed Scheme 32 3.3.1 Performance of the Proposed Scheme 32 3.3.2 Decision of the Swapping Conditions for Security 34 3.3.3 Comparisons of the Proposed Scheme 35 3.3.4 Radius in the Proposed Scheme 37 4 A Generalized Visual Secret Sharing Scheme for Multiple Secrets 39 4.1 The Proposed Scheme 39 4.1.1 Definitions of the Access Structure 39 4.1.2 Generation of the Constructional Matrix 40 4.2 Experimental Results 44 4.3 Analysis of the Proposed Scheme 48 5 Visual Secret Sharing for Multiple Secrets 50 5.1 The Proposed Scheme 50 5.1.1 The Decryption Model of the Proposed Scheme 51 5.1.2 The Encryption Process of the Proposed Scheme 52 5.2 Comparisons and Experimental Results 59 6 Conclusions and Future Works 65 References 6

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors