隱私權一直是現代人十分重視的權力之一，為了保護隱私，密碼便由此產生了。自此之後，密碼便在各式各樣的需求上被使用著。密碼，變成一種學問亦稱之為密碼學，研究著如何能更安全、祕密的保護或傳送資訊。
現今，主流的密碼使用與研究為公私鑰加解密系統。公私鑰加解密系統的安全建立於數學計算的複雜度上，只要計算複雜度足夠，便可以讓密文於有效期限內不被他人計算出原文而洩露隱私或機密。
然而，量子計算的出現使得原有的計算複雜度安全不再可靠。藉由量子的特性，量子計算擁有強大的平行運算能力，許多的計算難題皆可以此平行運算能力解決。而另一方面，依著量子的特性亦開始不同的形式的密碼學─量子密碼學。
不同於傳統密碼學，量子密碼學可以檢測竊聽者的存在並且達到理論上的安全。現今，已存在許多量子密碼學的相關研究與應用，例如：量子金鑰分配、量子秘密通訊等等。本論文將針對量子秘密通訊與認證來討論相關的安全議題。
量子秘密通訊與認證是一重要的量子密碼學研究，其主要目標是讓想要通訊的雙方可以透過量子安全的傳送祕密訊息並且認證對方的身分。由於環境設定的不同，量子秘密通訊與認證協定所要面對挑戰便與其他多數的協定不同。
首先，本論文將指出多數量子秘密通訊與認證協定的共通缺陷。此缺陷將使得竊聽者可以進行中間人攻擊去獲得私密訊息，並且有能力去偽造一私密訊息傳與另一方。然後，本論文提出相對應的改進方法。之後，探討三方參與者的環境。在一個不誠實的第三方協助需要秘密通訊的雙方進行量子秘密通訊與認證協定情況下，其第三方可以使用偽冒身分、竄改及中間人攻擊手段，來使得秘密通訊不再安全合適。最後，本論文提出一對應的方法，藉由通訊雙方的再次檢查，使得量子秘密通訊與認證協定可以免去第三方攻擊的問題。

Privacy is currently one of the most crucial issues. Cryptography has been developed for protecting privacy and is used ubiquitously. Cryptography is also under investigation to develop a more secure approach to protect or transmit information.
The most popular cryptosystem for applications and studies is the public-key cryptosystem. The security of most of the public-key cryptosystem is based on computational complexity, which can be easily solved by quantum computer.
This is because based on quantum mechanism features, quantum computers possess the powerful ability of parallel computing to solve numerous computing problems in a short period. Consequently, another type of cryptography, also based on quantum mechanism features, is quantum cryptography.
Differing from traditional cryptography, quantum cryptography detects eavesdroppers and achieves a theoretical security level. There are numerous applications and studies in quantum cryptography such as quantum key distribution and quantum secret communication. The focus of this thesis is on the security of quantum secret communication with authentication (QSCA).
QSCA, which allows two communicants to communicate directly and to authenticate each other in public channels, is a crucial research in quantum cryptography. Because of different environment assumptions, the challenges of QSCA protocols differ from other quantum cryptography protocols.
This thesis indicates a common shortcoming of QSCA protocols that allows an eavesdropper to execute a man-in-the-middle (MIM) attack to uncover the secret message and forge a secret message to the receiver. Consequently, a possible solution is proposed. Second, a discussion is presented regarding QSCA protocols in three-party agents, a third party Trent, and two communicants. A dishonest Trent can perform impersonate attack, modification attack, and MIM attack to undermine the security of QSCA protocols. Finally, the thesis provides a possible solution to check the quantum state by the two communicants, to enable the QSCA protocol to prevent the dishonest Trent.

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