現今PKI的發展，已大量應用私密性、認證性、整合性及不可否認性於網路通訊中；其公開金鑰系統管理，使用者A首先產生自己的公開金鑰及私密金鑰對，A在利用私密金鑰所進行的訊息簽章後，使用者B可使用A的公開金鑰進行其簽章訊息的驗證；同理，使用者B在利用的公開金鑰進行加密後，A便可利用私密金鑰進行密文的解密工作。目前的公開金鑰系統中，此類系統的安全性大多是基於有線群及因數分解的離算對數問題上，例如：D.H, ELGAMAL, RSA及ECC系統。而在金鑰對系統的金鑰產生上，使用者A需要從憑證管理中心（CA）取得屬於A自己的憑證，而利用此憑證，我們便可以利用其公開金鑰進行相關的應用；另一方面，在標準上，我們利用標準格式來儲存憑證的內容，如X.509標準等。在1984年時，Shamir[26]提出一種以ID為基礎的公開金鑰密碼學的概念，一個使用者可以利用其ID與其公開金鑰的結合來進行相關的應用，也就是說，由使用者的相關私密金鑰是由信任的第三者所提供；但以目前來說，ID基礎之公開金鑰系統的運用上其實以比原公開金鑰系統來的少了[21]。
　　公開金鑰基礎鍵社(PKI)由於其應用的領域已包括了許多研究的主題，於本論文中，我們考慮三種在PKI的課題及相關的應用。
　　第一，我們提出一種新型態的公開金鑰格式稱做可視型公開金鑰系統。為了產生此種金鑰對，我們利用一種稱為”部分RSA金鑰產生”(Portion RSA)的方法來進行公開金鑰的產生。在利用部分RSA金鑰產生法來進行公開金鑰的產生時，我們將一個影像插入公開金鑰的產生中以當作其啟始參數，進而在論文提出了實驗及實做的結果以表示相關的說明。
　　第二，為了有效在多人使用的環境下使用其憑證，論文中提出一群組憑證(Group Certificate)的概念，在論文中，我們利用GQ演算法，進行相關公開金鑰的產生，而可應用在多個使用者的環境裡，其中，每個使用者皆可以擁有自己的私密金鑰；進行簽章驗章時，只需進行共同擁有的憑證驗證即可。
　　最後，為了兼顧學術及應用，我們提出一設計密碼系統的分類方法，稱為密碼模式(Cryptographic Patterns)，如將此模式運用於設計密碼系統上，可以更為快速的進行系統設計，及更易達成一般性的效果，也就是說，利用模式的設計，可以使得設計出的系統更容易維護。

　Nowadays public key cryptography has been applied to daily life to achieve privacy, authenticity,integrity, and nonrepudiation in network communication. In the use of a public key system, user A first generates his/her public/private key pairs, and then user B can encrypt a message M to A or verify a signature S signed by A on M by using A’s public key. Some public key cryptosystems
whose security are based on discrete logarithons in finite groups or integer factorization are nowbeing
implemented worldwide, e.g. DH, Elgamal, RSA, and ECC. In the public/private key generation of these systems, A needs to apply for a certificate from a certificate authority (CA) to certify that the public key indeed belongs to A. There are some standards to define the format of the certificate, e.g.,X.509. In 1984, Shamir [2] proposed the concept of ID-based public key cryptography to eliminate CA and the certificate. An ID-based public key system allows the user to use his/her identity (ID)
as the public key. However, since the user’s corresponding private key is provided from the trusted
third party, it is considered that the security of ID-based system is less than the original public key
system [42].

　Public Key Infrastructure(PKI) is not only a comprehensive system but also a comprehensive topic including lots of related issues. In this dissertation, we consider three critical issues on PKI application and propose some valuable solutions and implementations.

　First, we proposed a new type of certificate format call visual public key system.To generate a key pair, we intruding the portion key generation scheme. With applying the portion key generation algorithm, we embedded the image into a public key with some initial key generation parameter. It also presents some experimental result to show the relation between the original image and modified
visual public key.

　Second, we describes the application the the PKI when using the ceritificate. For apply easily,we take some topics for using the key conveniencing such as AES speed up and VSS generating scheme. The AES algorithm, which is intruded by NIST, has been the standard encryption lgorithm
recently. We present a scheme to speed up this algorithm about 3-5% performation.

　Finally, for apply the the PKI when using the ceritificate easily, we take some topics for using the key conveniencing such as AES speed up and VSS generating scheme. The AES algorithm, which is intruded by NIST, has been the standard encryption algorithm recently. We present a scheme to speed up this algorithm about 3-5% performation. And to apply completely, we also introduce the various application and build the related component become a framework called icarus( Integreated
cryptographic application and utitilities suite) framework. And presents its application, there are
CA, RA, Secure Server, and Authentication Server.

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