[[alternative]]The Study of Key Management System for Wireless Sensor Network

計畫編號：NSC94-2213-E032-015研究期間：200508~200607研究經費：534,000[[abstract]]隨著無線傳輸技術之發展與微機電技術的進步，無線感測網路的技術 越來越成熟，應用範圍也越來越廣泛，其中包括軍事、環境科學、醫療健 康、空間探索、家庭照護和商業應用等領域。無線感測網路是由隨機散佈 的感測器節點以自我組態的方式建構而成，透過節點中的感測器量測所需 的資訊，並將此蒐集到的數據以無線電波傳輸的方式送到資料彙集中心或 基地台(base station)，再進行後續的處理與運用。一般來說，為防止攻擊者 破壞整個無線感測網路功能運作，無線感測網路至少需包含下列幾個安全 功能：可用性、鑑別性、私密性與完整性。在目前資訊安全技術中，可以 提供這些功能的技術都必須有一安全的密鑰予以協助，方能達到目的，甚 至此密鑰之安全與否將直接影響整個系統安全及功能的達成。密鑰管理是 確保密鑰安全的關鍵的技術，其最主要的目的就是要確保密鑰的安全，包 括密鑰的產生、傳送、驗證、使用、更換、儲存、備份、使用期限與作廢 等，每個程序都要確保密鑰的私密、正確及安全。然而，由於在無線感測 網路中無實體網路連結基礎架構、節點間間歇性連接、與節點電力、計算 能力與記憶空間均受限等因素，使得研究發展實用的無線感測網路密鑰管理技術相當困難，也由於這些限制條件，使得傳統有線網路的密鑰管理技 術在無線感測網路中均無法有效運作。 本計畫擬研究發展一適用於無線感測網路的計算成本低、記憶空間小 和通訊頻寬需求少的密鑰管理技術，而低計算成本和低通訊頻寬需求除提 昇效率外亦減少電力的消耗以延長感測節點壽命。此系統必須確保會談密 鑰的安全強度，即使感測節點有變動(新增、移動或停止運作)情形時，仍必 須確保系統的Forward Secrecy 和Backward Secrecy。藉此希望能增進無線 感測網路的安全機能。[[sponsorship]]行政院國家科學委員

[[alternative]]The Study of Key Agreement in Dynamic Groups without Trusted Third Party

計畫編號：NSC90-2213-E032-017研究期間：200108~200207研究經費：327,000[[sponsorship]]行政院國家科學委員

A Digital Image Copyright Protection Scheme Based on Visual Cryptography

[[abstract]]A simple and efficient watermark method is proposed in this paper. The watermark method is an excellent technique to protect the copyright ownership of a digital image. The proposed watermark method is built up on the concept of visual cryptography. According to the proposed method, the watermark pattern does not have to be embedded into the original image directly, which makes it harder to detect or recover from the marked image in an illegal way. It can be retrieved from the marked image without making comparison with the original image. The notary also can off-line adjudge the ownership of the suspect image by this method. The watermark pattern can be any significant black/white image that can be used to typify the owner. Experimental results show that the watermark pattern in the marked image has good transparency and robustness. By the proposed method, all the pixels of the marked image are equal to the original image.[[notice]]補正完

Watermark in color image

[[abstract]]There is an increasing number of products to be saved in digital form. In the digital world, we can preserve products forever, but there are also disadvantages such as easy copying. The watermark is an important protection method in digital media. When a media is publicly available or put on a network, it is very easy to copy or be misappropriated. The author can prove ownership by using an open algorithm and security key to extract the watermark. Therefore, a watermark technique must resist attacks and cannot influence image quality. We propose an image watermark technique based on the spatial domain in a color image. We present experimental results which prove that our method can resist certain attacks.[[notice]]補正完畢[[notice]]補正完畢[[conferencetype]]國際[[conferencedate]]20021101~2002110

An Efficient Decryption Method for RSA Cryptosystem

[[abstract]]This paper proposes an efficient method to implement RSA decryption algorithm. RSA cryptosystem is the most attractive and popular security technique for many applications, such as electronic commerce and secure Internet access. It has to perform modular exponentiation with large exponent and modulus for security consideration. The RSA cryptosystem takes great computational cost. In many RSA applications, user uses a small public key to speed up the encryption operation. However, the decryption operation has to take more computational cost to perform modular exponentiation by this case. This paper proposes an efficient decryption method not only based on Chinese remainder theorem (CRT) but also the strong prime of RSA criterion. The proposed decryption method only takes 10% computational costs of the traditional decryption method. It also reduces 66% computational costs than that of decryption methods based on CRT only. In a word, the speed of our proposed method is almost 2.9 times faster than the decryption method based on CRT only. The proposed method enhances the performance of the RSA decryption operation.[[sponsorship]]IEEE Computer Society Technical Committee on Distributed Processing (TCDP); Tamkung University[[notice]]補正完畢[[conferencetype]]國際[[conferencetkucampus]]淡水校園[[conferencedate]]20050328~20050330[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]臺北縣, 臺

鑑古識今：從課程發展策略的視角看課程改革

This article, by analysing the Mathematics curriculum development of Hong Kong in the period 1940s-1980s, aimed to learn from the past. It stressed that the education bureau had adopted various effective strategies in curriculum development, though it centrally-controlled the development. The education bureau had adopted incremental model through consideration of context, implemented curriculum orderly and used techniques of absorptive politics to introduce strengths and ideas from grassroots and to interact with teacher associations. Inquiring from historical development, this article raised five dimensions of thought for curriculum development: strategies need to consider trends of recent change, considering the context of society, provision of space and flexibility when using top-down approach, accepting voice from grassroots, and investigating the possibility of devolution of power when responding to requests. 鑑古識今，本文從分析1940 - 1980期間香港小學數學課程的發展，指出香港過往的數學課程發展雖然由桝育 部門作「中央監控」，但亦採取「漸進發展」的課程發展模式，因應時勢，有序地推行數學課程改革，而且 以吸納政治的技巧，引入民間力量和聲音，著重與桝師團體的互動。從歷史發展的探索，本文提出五方面的 思考：課程發展策略要因應時勢發展，需因地制宜，雖由上而下但仍給予自主空間和彈性，容納民間聲音， 以及探討權力下放的可行性以回應時代需求