無線感測網路（WSN）作為一種新興的技術，它擁有廣泛的應用前景。但由於它本身具有的特性，其存在應用上的限制，例如：記憶體容量小導致處理能力低下、較低的傳輸速率與受到限制的能源供給。
解決WSN中的安全問題是一個相當艱鉅的議題。而現今感測網路的安全協定面臨兩大挑戰。第一，需要一個優秀的演算法，使微處理器能以很小的成本進行運算。第二，由於能源的限制是WSN中最重要的問題之一，在設計安全協議時，要考慮如何極小化計算資源的消耗。
在感測網路中，已經有許多網路安全設計被提出並且作為完整的安全架構。 SNEP [1] 依靠簡單的加密基元，其設計致力於節省計算開銷。為了減輕封包傳輸量的壓力，在[1]中明確闡述了計數器同步的方法。然而，當無法同步時，重新同步將浪費大量的能量。此外，為了使所有相鄰節點同步而存儲共用計數器，則會導致記憶體過度使用。[2]提出縮小為加強安全性的封包長度，利用選擇一個來自標頭的臨時欄位，可以些微減少封包的負擔。不幸的是，資訊的新鮮度卻在TinySec中被忽略。但計算效率在MiniSec [3]中獲得改進 [3]採用偏移密碼本（OCB）的認證加密模式，於單通道中確保保密性和真實性，同時也使用一個隱含的發送計數器以保證新鮮度。我們也觀察到OCB機制中，存在無法確保完整性的安全漏洞。

根據觀察，串流加密器在WSN領域中並無完善的研究。但它卻相當重要，因為它可以確保在即時性應用的安全。此外，與區塊加密器相比，串流加密器的執行速度更快。雖然現今在WSN已有大量研究串流加密器的著作[1][4][5]，但只有[1]提供完整性保護。然而，為確保完整性，[1]需要利用一個不同的加密器。而對於存在碰撞的臨時欄位，仍需要一個可被增額的臨時欄位。
考慮所有因素，我們可以推斷，在目前感測網路下的串流加密器，無法提供完整性的保護。因此，我們提出新的認證串流加密器，它擁有簡單、高效能、快速的優點，無論是基於硬體還是軟體都容易被實現。此外，我們的提案同時也能夠滿足感測網路的基本需求。
此外，當[1]在CTR和CBC MAC模式中執行加密和認證時，所提供保密性和完整性的成本是僅提供保密性成本的兩倍。相反地，我們的串流加密器花費與[1]幾乎相同的時間，並可同時提供保密性與完整性。

Wireless Sensor Network is emerging technology that feature wide range of possibilities and great aspects. Concurrently, those unique characteristics, in turn, lead to several limitations: restricted processing power with small memory size, relatively low data rate channel due to a tiny physical size and power supply constraint.
Solving security issues in WSNs is quite a formidable task indeed. Security protocols for the sensor networks now face the two major challenges. First, an algorithm is required to perform at affordable level of computation so that microprocessors could handle. Second, a security protocol should use minimum power resource since energy constraint is one of the most significant issues in WSNs.
Several security designs have been proposed as a complete security architecture for the sensor networks. SNEP [1] devoted its effort to saving computation overhead by relying on the simple cryptographic primitives. To reduce packet size pressure, an explicit counter sharing method is introduced along with [1]. However, when the synchronization is lost, resynchronization will waste high amount of energy. Furthermore, storing a shared counter for all of its neighbors always brings on excessive memory usage. [2] intended to shrink packet length imposed by the security features. By choosing a nonce to be made up from packet header, packet overhead is slightly shortened in result. Unfortunately, freshness is omitted in TinySec. Computation efficiency is boosted in another proposal MiniSec [3]. [3] utilized the Offset Codebook (OCB) Authenticated Encryption mode to assure both privacy and authenticity in a single-pass while employing an implicit transmitted counter to enable freshness. We also observed a vulnerability on integrity of OCB scheme.
Our observation shows that stream cipher is not well-studied in WSN. Stream cipher is important because it can maintain security of the real-time applications. Moreover, when compared with block ciphers, it performs at a higher speed. Although there are plenty of stream ciphers [1] [4] [5] are exhibited in literature for WSNs, only [1] maintains integrity protection. Nevertheless, [1] utilizes a separate cryptographic operation for integrity perspective, and even requires nonce to be incremented for each block which indicates early collision of the nonce.
Taking all these factors into consideration, we may safely come to the conclusion that there is no such thing as stream cipher with integrity support for the sensor network security. Based on the points discussed above, we introduced a new Authenticated Stream Cipher which is simple, efficient and fast, and yet, easy to implement in either hardware or software. Thus, our proposal satisfies the important requirements for the sensor networks.
In addition, while [1] is encrypting and authenticating in CTR encryption and the CBC MAC, the cost for privacy-and-authenticity is twice the cost for privacy alone. In contrast, our stream cipher achieves authenticity and privacy in almost the same amount of time that [1] allocates.

[1] Adrian Perrig, Robert Szewczyk, Victor Wen, David Culler and J.D. Tygar, "SPINS: Security protocols for sensor networks," ACM Journal of Wireless Networks September, pp. 521-534, 2002.
[2] Chris Karlof, Naveen Sastry and David Wagner, "TinySec: A Link Layer Security Architecture for Wireless Sensor Networks," in Second ACM Conference on Embedded Networked Sensor Systems (SensSys), 2004.
[3] Mark Luk, Ghita Mezzour, Adrian Perrig and Virgil Gligor, "MiniSec: A Secure Sensor Network Communication Architecture," in Information Processing in Sensor Networks (IPSN), 2007.
[4] Tieming Chen, Liang Ge, Xiaohao Wang and Jiamei Cai, "TinyStream: A Lightweight and Novel Stream Cipher Scheme for Wireless Sensor Networks," 2010.
[5] Shish Ahmad, Mohd. Rizwan beg and Qamar Abbas, "Energy Efficient Sensor Network Security Using Stream Cipher Mode of Operation," in Int’l Conf. on Computer & Communication Technology, 2010.
[6] Ong Wang, Garhan Atterbury and Byrav Ramamurthy, "A Survey of Security Issues in Wireless Sensor Networks," IEEE Communications Surveys and Tutorials, 2006.
[7] Jason Hill, Robert Szewczyk, Alec Woo, Seth Hollar, David Culler and Kristofer Pister, "System architecture directions for networked sensors," ACM ASPLOS IX, p. 93, 2000 November.
[8] Phillip Rogaway, "OCB: Background," [Online]. Available: http://www.cs.ucdavis.edu/~rogaway/ocb/ocb-faq.htm. [Accessed January-June 2013].
[9] Phillip Rogaway, Mihir Bellare and John Black, "OCB: A Block-Cipher Mode of Operation for Efficient Authenticated Encryption," ACM Transaction on Information and System Security (TISSEC), vol. 6, pp. 365-403, 2003, August.
[10] Fasee Ullah, Masood Ahmad, Masood Habib and Jawad Muhammad, in Computer Research and Development (ICCRD), 2011.
[11] W.R.Heinzelman, A. Chandrakasan and H.Balakrishnan, "Energy efficient communication protocol for wireless micro-sensor networks," in IEEE Hawai International Conference on System Sciences (HICSS), Hawai, 2000.
[12] E. Ulziisaikhan, "Wireless Sensor Networks Security Survey on ATWN course, CSIE, NCKU," Tainan, 2012.
[13] Alexander W.Dent and Chris J.Mitchell, User's Guide to Cryptography and Standards, 2005.
[14] Yong Wang, Garhan Attebury and Byrav Ramamurthy, "A Survey of Security Issues in Wireless Sensor Networks," CSE Journal Articles, vol. 8, p. Paper 84, 2nd Quarter 2006.
[15] A. Victor, A. Khader, C. Rao and A. Mehta, "Build an IEEE 802.15.4 Wireless Sensor Network for Emergency Response Notification for Indoor Situations".
[16] "Related technologies," Purelink, [Online]. Available: http://www.purelink.ca/en/technologies/related-technologies.php. [Accessed 01 06 2013].
[17] Rickard Söderlund, "Energy Efficient Authentication in Wireless Sensor Networks, Final Thesis," Linköpings universitet, Department of Computer and Information Science, 2006.
[18] Tatiana Bokareva, "Mini Hardware Survey," The University of New South Wales, [Online]. Available: www.cse.unsw.edu.au/~sensar/hardware/hardware_survey.html. [Accessed 6 2013].
[19] J. Black, "Survey of Authenticated Encryption," 2003.